KR101215358B1 - Advanced power saving in communication terminal, communication system and power control method - Google Patents

Abstract

In order to reduce power saving and avoid collision of signals in a wireless network.
According to the present invention, each station receives a signal from another station in the group and automatically transitions to a power saving state based on the transmission of the signal by itself. In addition, each station sets each transmission timing so as not to overlap with the transmission timing of other stations based on the data elements included in the beacon signal. In addition, the transmission timing of each station is determined for each transmission.

Description

Communication terminal device, communication system and power control method {ADVANCED POWER SAVING IN COMMUNICATION TERMINAL, COMMUNICATION SYSTEM AND POWER CONTROL METHOD}

The present invention relates to a technique for communicating between a plurality of communication terminal devices.

In recent years, the miniaturization and lightening of the information terminal have been realized, so that carrying the information terminal has become common. Along with this, researches are being actively conducted to build a wireless ad hoc network as an on-demand type of communication. Since an ad hoc network does not require a base station or an access point, the network can be easily constructed even in a place where such an infrastructure does not exist. Using this ad hoc network, for example, a plurality of users can gather together a portable game machine and wirelessly communicate with each other to enjoy a game together.

Ad hoc networks are constructed by communicating between terminals using technologies such as IEEE 802.11 and Bluetooth. There is no problem in the case where the power supply can always be received from an external power source. However, since the portable terminal is driven by limited battery power, it is desirable to suppress battery consumption as much as possible. Therefore, power control processing in the power saving mode is standardized even in a communication standard such as IEEE 802.11.

1 is a timing chart showing a station operation in a power saving mode standardized to 802.11. First, any of the stations A to D transmits a beacon signal. The beacon signal is a notification signal and communicates to all stations. A time window, called the Announcement Traffic Indication Message (ATIM) window, is initiated following the transmission of the beacon. This window is the time that the node must remain active. In the power saving mode of the 802.11 standard, each station transmits an ATIM signal during an ATIM window, thereby preventing another station from sleeping.

In the example of FIG. 1, station B transmits an ATIM signal unicast to station C, and station C returns an ACK signal to station B. FIG. Since stations A and D are not transmitting or receiving ATIM signals, they may enter a sleep state after the end of the ATIM window. On the other hand, station B and station C cannot enter the sleep state, and after the end of the ATIM window, station B transmits data to station C, and station C returns an ACK signal to station B after receiving the data. Before this beacon interval ends, stations A and D are activated to transmit or receive beacon signals. In the next ATIM window, no station transmits or receives an ATIM signal, so all stations enter sleep after the ATIM window ends.

In the timing chart shown in FIG. 1, an extremely simple case is taken to explain the power saving mode of the 802.11 standard. However, when a network is constructed by a plurality of portable game machines, status information of each game machine is passed to each other. More signals will be communicated because they need to be given. In game applications with high real-time demands, the status information needs to be updated frequently, and data is preferably transmitted by multicast communication.

In the case of performing multicast communication, the ATIM window is set even though the ACK signal is not returned as a problem in the power saving mode of the 802.11 standard. In the standard power saving mode, ATIM signals from other stations are monitored between ATIM windows to determine which stations can sleep. In other words, during this period, all stations do not transmit or receive status information. To start. Assuming a game application requiring a low delay, for example, a racing game, a situation in which a player operates a car while holding a direction key frequently occurs. At that time, the status information always needs to be transmitted to another portable game machine, but the status information cannot be transmitted between the ATIM windows.

In addition, in a wireless environment in which a plurality of game machines exist, signal collisions sometimes become a problem. If the signal is not properly received, for example, retransmission control can be performed. However, in a game application requiring low delay, the retransmission control may be difficult in time.

Therefore, an object of the present invention is to provide a technique for realizing power saving in communication between a plurality of terminals. It is also an object of the present invention to provide a technique for realizing efficient transmission of signals in communication between a plurality of terminals.

SUMMARY OF THE INVENTION In order to solve the above problems, one embodiment of the present invention is a communication terminal device that forms a group with one or more other communication terminal devices and performs communication in a group, comprising: a receiving unit for receiving data signals from another communication terminal device, and other communication; A communication terminal device comprising a transmission control unit for counting the number of data signals received from a terminal device and a power control unit for entering a power saving state based on the counted number of data signals. Here, the data signal means a cluster of data aggregates that are transmitted or received in succession in time, and the communication terminal device processes the cluster as a single data signal with the cluster data set.

In the communication terminal apparatus, the power control unit may enter a power saving state based on the transmission process. Specifically, the power control unit may enter the power saving state based on the terminal device transmitting the data signal a predetermined number of times.

According to another aspect of the present invention, there is provided a method of transmitting data signals from one or more other communication terminal devices forming a group, counting the number of data signals received from another communication terminal device, and saving power based on the counted number of data signals. It provides a power control method comprising the step of entering a state.

Another embodiment of the present invention provides a function for allowing a computer to receive data signals from another communication terminal device, a function of counting the number of data signals received from another communication terminal device, and transition to a power saving state based on the counted number of data signals. It provides a program to execute the function.

Still another aspect of the present invention is a communication terminal apparatus which forms a group with one or more other communication terminal apparatuses to communicate in a group, comprising: a receiving unit for receiving a notification signal including a data element for determining transmission timing, and a predetermined notification; Provided is a communication terminal device including a transmission control unit for determining a transmission timing of its own data signal based on a data element included in the signal, and a transmission unit for transmitting a data signal to another communication terminal device at the transmission timing determined by the transmission control unit. .

According to another aspect of the present invention, there is provided a method for receiving a notification signal including a data element for determining a transmission timing of its own data signal, and based on a data element included in a predetermined notification signal, timing of transmission of the own data signal is determined. And a step of transmitting a data signal to another communication terminal device at the determined transmission timing.

Another aspect of the present invention provides a function of receiving a notification signal including a data element for determining a transmission timing of a data signal to a computer, and based on a data element included in a predetermined notification signal, timing of transmission of the own data signal is determined. A program for executing a function of determining and a function of transmitting a data signal to another communication terminal device at a determined transmission timing is provided.

Still another aspect of the present invention is a communication system for communicating between a plurality of communication terminal apparatuses, the first power saving mode in which a plurality of communication terminal apparatuses enter a sleep state when one of the plurality of communication terminal apparatuses sends a notification signal. There is provided a communication system having a power saving mode and a second power saving mode in which one communication terminal device enters a sleep state autonomously based on the number of data signals received from another communication terminal device reaching a predetermined value.

Still another aspect of the present invention is a communication terminal device configured to communicate with one or more other communication terminal devices in a group, comprising: a transmitting unit for periodically transmitting a predetermined notification signal including data elements having different values for each notification signal; It provides a communication terminal device having a transmission control unit for determining the transmission timing of its own data signal based on the data elements included in the notification signal.

Another aspect of the present invention is a communication system for communicating between a plurality of communication terminal devices, wherein one communication terminal device periodically transmits a predetermined notification signal including data elements having different values for each notification signal, and the plurality of communication devices. Each of the terminal apparatuses provides a communication system for determining the transmission timing of its own data signal on the basis of the data elements in the notification signal, and transmitting the data signal to other communication terminal apparatuses at the determined transmission timing.

A still further aspect of the present invention is a communication terminal device having a selection unit for classifying at least two types of data signals to be transmitted and a storage unit for storing the classified data signals before transmission, wherein the one type of data signals in which the storage units are classified are stored. An overwrite type memory for storing and a FIFO type memory for storing other types of data signals are provided.

In addition, any combination of the above components and the conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, and the like are also effective as aspects of the present invention.

According to the present invention, power saving between terminal devices can be realized. Moreover, an object of the present invention is to provide a technique for realizing efficient transmission of signals in communication between multiple terminal devices.

1 is a timing chart showing station operation in a power saving mode of the 802.11 standard.
Fig. 2 is a diagram showing a communication system in the first embodiment.
FIG. 3A shows a state in which four stations are performing unicast communication with each other, and FIG. 3B shows that one station becomes an access point, and another three stations perform unicast communication with the access point. It is a figure which shows the state which exists.
4 is a diagram illustrating a state in which each station is performing multicast communication.
Fig. 5 is a timing chart showing the station operation in the power saving mode of the first embodiment.
6 is a functional block diagram of a game machine.
7 is a timing chart showing a station operation in a power saving mode improved as a modification of the first embodiment.
8 is a timing chart showing a station operation in a power saving mode improved as a new modification of the first embodiment.
9 is a timing chart showing a station operation for realizing the self-controlled power saving mode and the collision avoidance mode of the second embodiment.
10 is a timing chart showing a transmission operation of each station in two groups.
11 is a timing chart showing a station operation for realizing a self-controlled power saving mode and a collision avoidance mode.
FIG. 12 is a diagram showing details of the communication processing unit shown in FIG. 6.
13 is a diagram illustrating a configuration of a transmission control unit.
14 is a timing chart illustrating transmission of a control signal.

2 shows a communication system 1 according to an embodiment of the present invention. The communication system 1 is constituted by a plurality of communication terminal devices (hereinafter referred to as "communication terminals" for convenience), and here, four communication devices 2a, 2b, 2c, 2d are illustrated as communication terminals. have. The number of game machines 2 is not limited to four but may be other than four. The game machine 2 has a wireless communication function, and a plurality of game machines 2 form a wireless network by gathering. For example, a wireless ad hoc network may be constructed by using a standard of a wireless LAN such as IEEE 802.11. In the MAC layer technology of IEEE 802.11, CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) is employed as an access control method. Data is transmitted after the data is confirmed to be empty. This waiting time is a minimum time plus a random length of waiting time for each terminal, and a plurality of terminals are simultaneously transmitted after a certain time after the last communication to prevent the occurrence of a collision between signals. have. In unicast communication, it is judged whether or not the data is actually transmitted correctly or not by an ACK (Acknowledge) signal from the receiving side. If there is no ACK signal, it is assumed that there is a communication failure, and data is retransmitted.

By establishing an ad hoc network, the communication system 1 can realize communication between a plurality of game machines 2 without requiring an infrastructure such as a base station or an access point. Since each game machine 2 receives the status information in the other game machine, it becomes possible for multiple players to enjoy the same game application simultaneously.

* Game applications can be divided into two groups: games with high real-time demands and games with low real-time. A game having high real-time demand is a game in which a game progresses quickly, such as a fighting game or a racing game, and the user's operation input needs to be reflected in the output of the game screen or the like. On the other hand, games with low real-time demands are games with relatively slow progress of games such as fighting games such as chess and mahjong, and role playing games (RPGs).

The game screen is updated at a predetermined frame rate or refresh rate. In the present situation, the correction speed of one field is about 16.7 msec (1/60 sec), so at least once per field (16.7 msec) in a game application where the demand for real time is high, that is, low latency is required. It is desirable to inform the other game machine of its status information, and to know the status information of the other game machine. Status information is absolute information such as the position on the course, the direction of the car, and the speed in a racing game. In this case, the absolute information is because the reliability of the communication in the wireless environment is not high. If the sufficient reliability can be secured, the difference information between the past and the present can be known. In the communication system 1, each game machine 2 independently executes an application asynchronously. In addition, in a game application that does not require low delay, retransmission processing may be performed even if data for each field cannot be updated. Therefore, there is little risk of greatly affecting the application processing.

Below, three types of communication systems which implement | achieve the communication system 1 by direct communication of game machines are shown. Here, the IEEE 802.11 protocol is used as the communication standard. The IEEE 802.11 protocol has an advantage of easy access to the Internet compared to a protocol such as Bluetooth. By adopting IEEE 802.11 as the communication protocol, the game machine 2 can not only establish a wireless network but also connect to other terminals via the Internet, thereby improving the expandability of the communication system 1.

(Type 1)

In type 1, each station performs unicast communication in which a single counterpart is designated. 3A shows a state where four stations are performing unicast communication with each other. The station also corresponds to the game machine 2 in the communication system 1. In the 802.11 protocol, each station transmits status information for the other three stations. Therefore, in unicast communication, communication of status information is performed 12 times in total, and considering the ACK signal returned as a response, a total of 24 communication is performed. In applications requiring low latency, these 24 communications need to be performed in one field. Under CSMA / CA, the premise is that the control does not collide with the packet, but it is not actually easy to allow 24 times of communication in 16.7 m seconds while avoiding the collision of the packet. As the number of stations increases, the number of communication required per field increases. For the above reason, the type 1 communication method shown in FIG. 3A can be said to be an effective method for game applications that do not require low latency.

(Type 2)

In type 2, one station functions as an access point, and unicast communication is performed between stations. 3B shows a state where station A becomes an access point and the other three stations are in unicast communication with station A. FIG. Station A receives status information from the other three stations B, C, and D. The station A organizes its own status information and the status information of the stations C and D into one packet and transmits it to the station B. Similarly, station A transmits the status information of three stations other than station C to station C, and transmits the status information of three stations other than station D to station D. Therefore, in this unicast communication, communication of status information is performed six times in total, and in consideration of the ACK signal returned as a reception response, a total of 12 communication is performed. Compared with the type 1 communication system shown in Fig. 3A, the load on the host CPU of the station A serving as the access point cannot be denied. However, since the number of communication can be reduced, data communication requiring faster speed than the type 1 is required. This is excellent.

(Type 3)

In type 3, each station performs multicast communication. In an 802.11 ad hoc network, a basic service set ID (BSSID) is set as a random value for each network to distinguish it from other networks. Thus, each station can transmit its data frame in multicast to the stations forming the group within the same basic service area by including the BSSID in the data frame. When using a communication protocol other than 802.11, each station may perform multicast communication by designating addresses of three different stations.

4 shows a state in which each station is multicast communicating the same data. In other words, the station A includes the BSSID in the data frame and transmits its status information in one packet. The same applies to the stations B, C, and D. Therefore, in this multicast communication, communication of status information is performed four times in total. On the other hand, in the multicast communication, the ACK signal is not returned. Therefore, compared with the type 1 and type 2 communication systems shown in Figs. 3A and 3B, the number of communication can be significantly reduced, which is optimal for data communication requiring high speed and processing load in each station. Also does not grow. Therefore, the type 3 communication method shown in FIG. 4 can be said to be the most effective method for game applications requiring low latency.

As mentioned above, three types can be considered for the communication system in the communication system 1 of this embodiment, but it is preferable to save power of the game machine 2 (station) in any type. In the wireless ad hoc network terminal as well as the cellular phone terminal, realizing the intermittent operation on the time base greatly contributes to the power saving. In the following, only a part of the air interface is operated with extremely low power consumption due to the interruption of current to the bias circuit of the transceiver part (mainly composed of analog circuits) of the air interface, or the clock stop of the modem / MAC part. Or, the operable state is called a sleep state, and all the functions of the air interface are operating or the actuated state is called a start state.

(Example 1)

In Example 1, power saving is achieved by lengthening the sleep state. On the other hand, considering the realization of power saving, the power saving is generally easy because the sleep state can be set longer for applications in which low latency is not required. The following describes a latency strict game application requiring high speed and a communication method capable of realizing power saving even under such an environment.

Fig. 5 is a timing chart showing the station operation in the power saving mode of the first embodiment. In this timing chart, the beacon signal is a notification signal and communicates with all stations. Beacon frames include mandatory fields such as time stamps, beacon intervals, capability information, service set IDs, and supported rates, FH parameter sets, DS parameter sets, CF parameter sets, and IBSS parameters. Options fields such as set, TIM, etc. are included. The option information is only present if it needs to be used. The station transmits a beacon signal after waiting for a random waiting time called backoff from a target beacon transmission time (TBTT) corresponding to the exact last time of the previous beacon interval. If the station receives a beacon signal before its transmission time, transmission of the pending beacon signal is canceled. Therefore, in the communication system 1, only one station transmits a beacon signal. Since the beacon frame needs to be processed by all stations, all stations are up and running before TBTT.

In the example shown in FIG. 5, the sender of the beacon signal is fixed, and the station A is responsible for beacon transmission. This allows a plurality of stations to simultaneously transmit a beacon signal, thereby avoiding a situation where the beacon signals collide with each other. In the communication shown in Fig. 5, the type 3 multicast communication is adopted, focusing on the high speed of data communication. As a result, each station does not need to monitor the response of the ACK signal, and it is possible to transmit status information in one packet to a plurality of stations.

In this timing chart, station A first sends a beacon signal for awake. A beacon signal for awake declares that all stations should be awake (started). This declaration is made using the empty field of the beacon frame, for example, an FH parameter set, a TIM, or the like, which is an optional field, is used. At this timing, all the stations are activated, and when the stations B, C, and D receive the awake beacon signal, they recognize that the timing for transmitting their own status information is on. After the transmission or reception of the awake beacon signal, each of the stations A, B, C, and D generates a random backoff time while maintaining the activation state, and determines the transmission time of its own status information. Subsequently, each station multicasts its status information to other stations at the determined transmission time. The timing chart of FIG. 5 shows a state in which data is multicast from each station at random timing. In addition, since collision avoidance control by CSMA / CA is performed, when data transmission is performed by another station at its own transmission time, it waits for the transmission to be terminated before sending its own status information. Data transmission by all stations is performed until the next sleep beacon signal is transmitted (beacon interval T ₁ ).

Subsequently, station A transmits a sleep beacon signal. The sleep beacon signal declares that all stations will enter the sleep state. This declaration is made using the empty field of the beacon frame, similarly to the case of the awake beacon. For example, an FH parameter set, a TIM, or the like which is an optional field is used. At this timing, all stations are activated, and when the stations B, C, and D receive the sleep beacon signal, they recognize that the system is in the sleep state, and control the bias circuit and the clock circuit to enter the power saving state (sleep state). . On the other hand, the station A enters the sleep state after the sleep beacon transmission.

All stations in the sleep state are activated to transmit or receive the next beacon signal after the predetermined time elapses, that is, after the beacon interval T ₂ , from the time when the sleep beacon signal is transmitted or received. The transition from the sleep state to the activated state is autonomously performed in the terminal using a timer or the like inside the air interface terminal. The start timing of each station is determined by a device dependent relationship such as the time until the internal analog circuit is stabilized. In addition, in order to realize high power saving, the later the start timing of each station is, the better it is. In this state, when the station A transmits an awake beacon signal, all stations maintain the start-up state, determine the time at which their status information is transmitted, and transmit at that time.

As can be seen from the timing chart shown in Fig. 5, in the first embodiment, the so-called start period and sleep period of the station are forcibly set by two types of beacon signals. Specifically, the predetermined time is divided into two time zones, and each station is controlled to transmit and receive data in one time zone and to enter a sleep state in the other time zone. This minimizes unnecessary startup periods and slips the remaining time to achieve high efficiency power savings.

Considering the field period (16.7 m seconds), the transmission period of the awake beacon, that is, (T ₁ + T ₂ ) is set to 16.7 m seconds or less, preferably shorter than 16.7 m seconds, for example, 16 m seconds. desirable. By setting the start cycle of the station to less than 16.7 m seconds, it is possible to transmit and receive status information at least once between fields. As a result, smooth game progression of a game application requiring low delay can be realized while providing a sleep period reliably.

When (T ₁ + T ₂ ) is set to a predetermined time, the beacon interval T ₁ may be determined by, for example, the number of game machines 2 participating in the network. If the number is large, the beacon interval T ₁ is long. If the number is small, the beacon interval T ₁ is short. Depending on the game application and the like, the transmission time of data by each station is expected to be almost several hundred microseconds. Therefore, it is considered sufficient if the beacon interval T ₁ is approximately 4m seconds. If the beacon interval T _{1 is set} to 4 msec and the beacon interval T ₂ is set to 12 msec, the sleep period of the station can be set to 75% of the total. The beacon interval T ₁ may be determined in consideration of the data modulation mode, game data size, and the like. Since the efficiency of power saving can be improved by increasing the value of T ₂ / (T ₁ + T ₂ ), the beacon interval T ₁ is preferably as short as possible.

The station A in charge of the beacon transmission may determine the beacon interval T ₁ in consideration of the above situation. Beacon spacing T ₁ may be changed dynamically, and beacon spacing T ₂ may be changed dynamically accordingly. For example, it is preferable that the station A adaptively changes the beacon interval T _{1 due} to external factors such as the increase or decrease of the number of game machines 2 or the change in the communication environment. When (T ₁ + T ₂ ) is set for a predetermined time, the value of T ₂ is determined according to the change of T ₁ , and when (T ₁ + T ₂ ) ≤the predetermined time condition exists, The value of T ₂ is determined by the change of T ₁ within the range of conditions. As a result, power control appropriate to the situation can be executed. In addition, the beacon interval value set by the station A is incorporated in the beacon frame. As a result, the stations B, C, and D can know the timing at which the next beacon is to be transmitted, and can transition from the sleep state to the start state in accordance with the timing.

The above assumes that at least one status information is updated in one field (16.7 msec), assuming that a low delay is required, but if the latency up to that level is not required, the beacon interval T _1. It is possible to set a long time for the beacon interval T ₂ for. In this case, the sleep period can be longer, and more efficient power saving can be realized. For example, at the request from the game application side, updating of status information may be realized at least once in two fields (33.3 m seconds) or at least once in three fields (50 m seconds).

6 is a functional block diagram of the game machine 2. FIG. The game machine 2 includes a game processor 3 for performing an operation related to game processing, and a communication processor 4 for performing an operation related to communication. The game machine 2 also includes a battery 16 for supplying power and a clock portion 18 for generating pulses at predetermined time intervals. The game processing unit 3 has an input unit 10, an application processing unit 12 and an output unit 14, and the communication processing unit 4 includes a MAC unit 20, a timer 22, a power / clock control unit 24, It has a PHY part 26.

The communication function in the first embodiment is realized in the communication processing unit 4 by a program loaded in a CPU, a memory, a memory, or the like, and here, the functional blocks realized by their linkage are described. The program may be built in the game machine 2 or may be supplied from the outside in a form stored in the recording medium. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

The input unit 10 is a group of operation buttons such as a direction key for receiving an operation instruction from the user, and the application processing unit 12 receives the operation instruction input from the input unit 10 and another game machine 2 received from the PHY unit 26. The game application is executed based on the status information of). The output unit 14 is composed of a display, a speaker, or the like, and the processing result of the application processing unit 12 is output. The own status information processed by the application processing unit 12 is stored in a buffer of the MAC unit 20. The clock unit 18 supplies a clock to the timer 22 and the power / clock control unit 24. In addition, although the timer 22 may exist as an independent structure as shown, it may be incorporated as a function of the MAC part 20, and may be incorporated as a function of the power / clock control part 24. As shown in FIG.

The battery 16 supplies power to the game processor 3, the timer 22, and the power / clock controller 24. The power / clock control unit 24 controls power supply and clock to the MAC unit 20 and the PHY unit 26. Specifically, the power / clock control unit 24 can transition the MAC unit 20 and the PHY unit 26 from the start state to the sleep state and also from the sleep state to the start state. The MAC unit 20 generates a beacon signal and also has a function of analyzing the beacon signal received from the other game machine 2 through the PHY unit 26.

When the game machine 2 is responsible for transmitting the beacon signal, the MAC unit 20 inserts a value of the beacon interval in the required field of the beacon frame, wherein the awake beacon or slip in the empty area of the option field in the frame. The flag of the dragon beacon is also added. The PHY unit 26 transmits a beacon signal at a predetermined timing. The timing at which the MAC unit 20 generates the beacon signal and the timing at which the PHY unit 26 transmits the beacon signal are controlled by the power / clock control unit 24.

If the game machine 2 is not responsible for transmitting the beacon signal, the MAC unit 20 analyzes the received beacon signal to determine whether to enter the power saving mode. Specifically, the MAC unit 20 determines whether the received beacon signal is for awake or sleep, based on the flag included in the option field. In the case of the sleep beacon signal, the MAC unit 20 sends an instruction to transition to the power saving mode to the power / clock control unit 24. The power / clock control unit 24 stops the clock supply to the MAC unit 20 and the PHY unit 26 to stop the power consumption in the MAC unit 20 and the PHY unit 26 to stop the operation. As a result, the MAC unit 20 and the PHY unit 26 enter the sleep state. At this time, the power / clock control unit 24 sets the timer 22 to activate the MAC unit 20 and the PHY unit 26 after a predetermined time has elapsed from the time of entering the sleep state. This timer control is performed based on the value of the beacon interval contained in a beacon frame. The value of the beacon interval is sent from the MAC unit 20 to the power / clock control unit 24. It is preferable that the time from the time of slipping to the start is set to a time slightly shorter than the beacon interval T ₂ . The timer 22 counts the pulses supplied from the clock unit 18 and supplies a wake signal to the power / clock control unit 24 after a predetermined time has elapsed. The power / clock control section 24 causes the MAC section 20 and the PHY section 26 to enter the startup state upon receiving the wake signal.

If the received signal is an awake beacon signal, the MAC unit 20 and the PHY unit 26 are already activated. In other words, the MAC unit 20 and the PHY unit 26 are activated by the above timer control to receive the awake beacon signal. The game machine 2 maintains its starting state until the next sleep beacon signal is received.

When the awake beacon signal is received by the PHY unit 26, the MAC unit 20 determines the transmission time of the status information using a random number, and the status information is obtained from the buffer at the transmission time. Read and send. If a different signal exists at the transmission time, the MAC unit 20 transmits the status information by shifting the timing to avoid a collision.

When the game machine 2 is responsible for the transmission of the beacon signal, the MAC unit 20 recognizes whether or not to enter the power saving mode by the timer 22. Based on this recognition, the MAC unit 20 transmits a sleep beacon signal or an awake beacon signal. When the sleep beacon signal is transmitted, the MAC unit 20 sends an instruction for transition to the power saving mode to the power / clock control unit 24. The processing by the power / clock control section 24 is as described above. When the awake beacon signal is transmitted, the MAC unit 20 and the PHY unit 26 are already activated at the time of transmission. That is, the MAC unit 20 and the PHY unit 26 are activated by timer control to transmit the awake beacon signal. The game machine 2 in charge of the beacon transmission maintains its starting state until the next sleep beacon signal is transmitted. When the awake beacon signal is transmitted, the MAC unit 20 determines the transmission time of the status information using a random number, and reads the status information from the buffer at the transmission time and transmits the status information.

7 is a timing chart showing a station operation in a power saving mode improved as a modification of the first embodiment. In this case, the sender of the beacon signal, which is the notification signal, is randomly selected, and stations A to D attempt to transmit the beacon after waiting for a random backoff time. In the case where the beacon caller is fixed, when the beacon caller leaves the network, it is necessary to select a beacon caller afterwards, but when the beacon caller is not fixed, free participation in the network in the communication system 1 is required. Alternatively, it is easy to withdraw. In this modified example, the beacon interval is fixed at 4 m seconds, for example. The operation from the awake beacon signal to the immediate sleep beacon signal is the same as the operation from the awake beacon signal shown in FIG. 5 to the sleep beacon signal. The sleep beacon signal is transmitted three times from any one of the stations A to D after the awake beacon signal. The station waits a random waiting time from the target beacon transmission time TBTT corresponding to exactly the last time of the previous beacon interval, and then transmits a beacon signal. If the station receives a beacon signal before its transmission time, the transmission of the pending beacon signal is canceled. Each station enters a sleep state by sending or receiving a sleep beacon signal.

The station operation shown in FIG. 7 needs to operate to transmit or receive the sleep beacon every 4 m seconds compared to the station operation shown in FIG. 5, and the power saving efficiency is slightly reduced, but the setting of the beacon interval can be simplified. There is an advantage that mounting is easy. In addition, since the beacon signal is generated in all the game machines 2, there is an advantage of uniform power consumption. It is also possible to change the beacon interval according to the data amount of the game application, the number of participation of the game machine 2 in the network, and the like. In the timing chart of Fig. 7, the 16 msec corresponding to the awake beacon signal period is divided into 4 equal parts and the beacon interval is 4 m sec. Therefore, it is also possible to set the beacon interval optimal for power saving by adjusting the beacon interval.

The difference from the station operation in FIG. 5 will be described using the functional block diagram of FIG. 6. In the example of FIG. 7, the MAC unit 20 in all game machines 2 generates a beacon signal. When the MAC unit 20 transmits or receives an awake beacon signal, the MAC unit 20 generates a sleep beacon signal three times at a predetermined beacon interval thereafter, and then generates an awake beacon signal. The other processing is the same as that described with respect to the station operation in FIG.

8 is a timing chart showing a station operation in a power saving mode improved as a new modification of the first embodiment. In Fig. 8, the sender of the beacon signal, which is a notification signal, is fixed at station A, and the beacon interval is variable. The sender of the beacon signal may be arbitrary, and the beacon interval may be fixed. The operation from the sleep beacon signal to the awake beacon signal is the same as the operation from the sleep beacon signal to the awake beacon signal shown in FIG.

In the modification shown in Fig. 8, signal transmission by similar time division multiple access (TDMA) is performed from the awake beacon signal to the sleep beacon signal. That is, the transmission time of each station is shifted by different offset times on the basis of the awake beacon signal so that the signal transmission time of each station does not overlap. For example, the offset time of the station A may be set to 400 microseconds, the offset time of the station B to 800 microseconds, the offset time of the station C to 1200 microseconds, and the offset time of the station D to 1600 microseconds by 400 microseconds. This offset time may be fixedly assigned to each station or may be dynamically allocated. As shown in the illustrated example, when station A always transmits a beacon signal, it is easy to fixedly assign an offset time of each station, and when a station transmits a beacon signal arbitrarily, consequently, a beacon signal is generated. The originating station may dynamically assign an offset time. For example, the allocation of the offset time is described in the blank area in the option field of the beacon frame by the station which transmitted the beacon, and transmitted to each station. When each station receives the awake beacon signal, each station recognizes its own offset time and transmits status information after the elapse of the offset time. By implementing similar TDMA communication in this manner, signal collision can be reliably avoided, and communication with excellent quality can be performed.

(Example 2)

In the second embodiment, in a network in which a plurality of communication terminals form a group, each communication terminal autonomously saves power by receiving signals from other communication terminals constituting the group. To distinguish from the power saving mode shown in Embodiment 1, the power saving mode in Embodiment 2 is often referred to as a controlled power saving mode.

In addition, in the second embodiment, each communication terminal determines its own transmission timing based on the notification signal transmitted from the coordinator existing in the network in order to avoid signal collision between the communication terminals. This function is called collision avoidance mode. In this collision avoidance mode, the transmission order of each communication terminal can be changed for each transmission. In an ad hoc network, a coordinator is a communication terminal which is a group member, and in an infrastructure network, a coordinator is an access point.

In addition, CSMA / CA is adopted as an access control method in the technology of the MAC layer of IEEE 802.11, and the premise is to avoid signal collision by sensing a carrier. However, the possibility of signal transmission from a plurality of communication terminals at the same time remains, in which case a signal collision occurs. Therefore, the collision avoidance mode of the second embodiment can be effectively used also in IEEE 802.11, and can also be effectively used in other communication protocols. Since the self-controlled power saving mode and the collision avoidance mode in the second embodiment can be realized mostly by software processing, there is an advantage that the mounting is easy.

First, in a network in which a plurality of communication terminals participate, for example, a preset of a station or negotiation on a lobby IBSS between applications in a normal IEEE 802.11 ad hoc mode or an infrastructure mode may be performed as follows. The communication parameters are determined. In the case where the station is the game machine 2, the communication parameters may be preset in the game program incorporated in the disc inserted into the game machine 2. When negotiating on the lobby IBSS, the coordinator notifies other group members of the communication parameters individually by unicast communication. This unicast communication can be performed in standard ad hoc mode.

<Communication Parameters>

a) frequency channel

b) Service Set Identity

c) Target Beacon Transmission Time (TBTT)

d) modulation / coding scheme of the physical layer

e) MAC address and station number (device number) of each station

f) IFS (Inter Frame Space) generation mode (802.11 standard or QoS based on IFS vector)

g) IFS vector value (valid only for QoS scheme by IFS vector)

h) Security mode / common key

In the above communication parameters, in the second embodiment, f) the case where the QoS method by the IFS vector is set as the IFS generation mode is taken as an example. g) The IFS vector value is the amount of time used to find the transmission time of each station, in microseconds. The IFS vector value includes IFS0, which determines the reference time of transmission, and IFS offset, which determines the offset time from IFS0. Also, as will be described later, the QoS method based on the IFS vector value is used in the collision avoidance mode for avoiding signal collision, and has no direct relationship with the realization of the self-controlled power saving mode in the second embodiment. In addition, more efficient communication can be realized by simultaneously executing the controlled power saving mode and the collision avoidance mode simultaneously.

Each station receiving the notification of the communication parameters switches the wireless I / F to the game mode according to the received parameters. The station number is 0 for the coordinator, and the other stations have values set in the communication parameters, respectively. Therefore, in a network composed of four stations, station numbers 1, 2, and 3 are assigned to three stations other than the coordinator, respectively. After completion of all players' transition to the game mode, the coordinator switches his wireless I / F to the game mode. Here, the game mode is a mode in which the player executes a game, and in this game mode, the self-controlled power saving mode and / or the collision avoidance mode in the second embodiment is executed. In this game mode, the power saving mode in the first embodiment may be executed, and the power saving mode in the first embodiment and the self-controlled power saving mode in the second embodiment may be selectively executed.

TBTT sets beacon transmission timing. Coordinator may set appropriate TBTT interval according to game application. For example, the TBTT interval is set short for game applications that require low latency, and the TBTT interval is set long for game applications that do not require low latency. Considering the field period (16.7 m seconds), for game applications requiring low latency, the beacon transmission period is preferably set to 16.7 m seconds or less, preferably shorter than 16.7 m seconds, for example, 16 m seconds. On the other hand, for game applications that do not require low latency, the beacon transmission period may be set to 16.7 m or more. Method also sets the TBTT according to the second embodiment is that even if the same as those described as the method of setting (T ₁ + T ₂₎ in Example 1. Fig. According to the self-controlled power saving mode in the second embodiment, since each station can shorten the startup period during the TBTT period, the sleep period can be increased by setting the TBTT interval longer.

9 is a timing chart showing a station operation for realizing the self-controlled power saving mode and the collision avoidance mode of the second embodiment. Each station has a function of forming a group with one or more other stations and communicating within the group. Here, groups, that is, networks, are configured in four communication terminals of stations A, B, C, and D. First, the collision avoidance mode of Example 2 is demonstrated.

In this timing chart, the beacon signal is a notification signal and is communicated to all stations. In the example of illustration, station A functions as a coordinator and is responsible for beacon transmission. As a result, a plurality of stations simultaneously transmit a beacon signal, thereby avoiding a situation in which beacon signals collide with each other, and at the same time, the station A can collectively control communication in the network. In the communication shown in Fig. 9, the high speed of data communication is emphasized, and type 3 multicast communication is adopted. As a result, each station does not need to monitor the response of the ACK signal, and it is possible to transmit status information in one packet to a plurality of stations.

Station A, which is the coordinator, is assigned a station number 0. Hereinafter, it is assumed that station number 1 is assigned to station B, station number 2 is assigned to station C, and station number 3 is assigned to station D, respectively.

Since the beacon frame needs to be handled by all stations, all stations are up and running before TBTT. Each station needs to go from sleep to wake up before sending or receiving a beacon signal. In addition, each station may transmit a data signal based on the transmission or reception of the beacon signal. In addition, the TBTT is notified to each station from the coordinator in advance, and therefore, each station can recognize itself the timing of the starting state from the sleep state.

In this timing chart, first, station A transmits a beacon signal. The beacon signal includes data elements for each station to determine the transmission timing of the data. The beacon signal is periodically transmitted according to the TBTT, and data elements included in the beacon signal include data elements having different values for each beacon signal.

In Embodiment 2, station A transmits the beacon signal including the beacon number, the number of IBSS stations, and the IFS vector value. The beacon number is represented by 4 bits of data, for example, and numbers from 0 to 15 are periodically assigned. The number of IBSS stations is the number of stations constituting the group, and is set to 4 in the example of FIG. 9. Among these data elements, data elements having different values for each beacon signal are beacon numbers, and the number of IBSS players and the IFS vector value are kept constant unless necessary. In addition, the IFS vector value included in the beacon signal is used when the third party participates in the IBSS or when another group generates a new IBSS in the same frequency band.

Each station determines the transmission timing of its own data signal so as not to overlap with the transmission timing of the data signal by other stations in the same network. The transmission timing is determined by each station determining its own transmission order in the group and using the determined transmission order and the IFS vector value. As described, the IFS vector value is notified by the coordinator in unicast communication and set in advance as a communication parameter.

The transmission order is determined at each station by the following equation, for example.

(Send Sequence Value) = (Station Number + Beacon Number) mod (Number of Stations)

Consider the transmission order of station A (station number 0). If the beacon number is 4, for example, the transmission order value is

(0 + 4) mod4 = 0

Is determined as. In addition, the transmission order value of 0 indicates that the transmission order is the fastest.

In this case, the transmission order value of station B (station number 1) is 1, the transmission order value of station C (station number 2) is 2, and the transmission order value of station D (station number 3) is 3. For this reason, when the beacon number is 4, the transmission order is determined in order of the station A, the station B, the station C, and the station D. FIG. In addition, the transmission order may be determined by another method so that the transmission order in the group of each station does not overlap.

Each station determines its own transmission timing using the transmission order value corresponding to its own transmission order. The transmission timing is determined by the following equation.

(Sending timing) = IFS0 + (sending sequence value) x IFS offset

Here, IFS0 is 15 μsec and IFS offset is 7 μsec. The transmission timing of station A

15 + 0 × 7 = 15μs

Is determined as. In this case, the transmission timing of station B is 22 microseconds, the transmission timing of station C is 29 microseconds, and the transmission timing of station D is 36 microseconds. The IFS offset is shown as Δt in FIG. 9.

On the other hand, CSMA / CA is adopted as an access control method in the MAC layer technology of IEEE 802.11, and each station has a function of transmitting data after confirming that the communication path is continuously empty for a predetermined time. The transmission timing determined here corresponds to the time for confirming that the communication path is empty, that is, the elapsed time after signal detection from another terminal apparatus for transmitting itself. Each station can transmit a data signal when time elapsed as a transmission timing after detecting a signal from another terminal device. Here, other terminal devices include other stations in the same group, but also include stations in other groups and other electronic devices.

The transmission timing, which is the time for confirming that the communication path is empty, is preferably set at as short intervals as possible. By setting the transmission timing short, the power saving function in the self-controlled power saving mode described later can be effectively realized. However, there is a possibility that a signal may not be well received at each station at a short time such as 1 μsec. Therefore, it is possible to improve the power saving by setting the transmission timing between, for example, about 10 microseconds to about 50 microseconds. It is desirable for the coordinator to set the IFS vector value appropriately based on the number of stations to keep each transmission timing within range.

As described above, by adding a station unique value, that is, its own station number, to the calculation of the transmission order value, it is possible to determine different transmission timings for each station. Thereby, each station can determine the transmission timing of its own data signal so that it may not overlap with the transmission timing of the data signal by another station. Therefore, according to the communication system 1 of the second embodiment, the possibility of collision of signals from each station can be avoided, and stable communication can be realized.

Each station multicasts its status information to other stations at respective transmission timings. The timing chart of FIG. 9 shows a state in which data is multicast from each station at the determined transmission timing. In the figure, the signal display made of dots therein indicates that the signal is properly received at the station.

In the collision avoidance mode of the second embodiment, the transmission order of each station can be changed for each transmission. This is realized by using beacon numbers having different values for each beacon signal in determining the transmission order value. In the above example, the case where the beacon number is 4 has been considered, but the case where the transmission order value is determined based on the next beacon signal, that is, the beacon signal having the beacon number 5 is considered.

The transmission order of station A (station number 0) is

(0 + 5) mod4 = 1

Is determined as. In addition, a transmission order value of 1 represents a second transmission order.

In this case, the transmission order value of station B (station number 1) is 2, the transmission order value of station C (station number 2) is 3, and the transmission order value of station D (station number 3) is 0. For this reason, when the beacon number is 5, the transmission order is determined in order of station D, station A, station B, and station C. FIG.

Using this transmission order value, each station determines the transmission timing. The transmission timing of station A

15 + 1 × 7 = 22μs

Is determined as. In the same calculation, the transmission timing of the station B is 29 µsec, the transmission timing of the station C is 36 µsec, and the transmission timing of the station D is 15 µsec.

In a wireless communication system 1, a situation in which a communication environment deteriorates frequently due to jamming or the like occurs. Particularly, under CSMA / CA control in IEEE 802.11b, since transmission of the device waits for its own transmission due to carrier detection, a situation may occur in which a signal cannot be transmitted due to jamming. Considering the signal transmission of stations in the same group, when the transmission order is fixed, there is a high possibility that the station assigned the last transmission order cannot transmit a signal as compared to other stations.

Therefore, in the collision avoidance mode of the second embodiment, by adding a beacon number to the calculation of the transmission order value, the transmission order of each station is changed and set for each transmission, that is, for each beacon interval between TBTTs. This makes it possible to equalize the transmission of the transmitters by all stations and avoid the situation where signal transmission from a specific station is always impeded. In the above example, the transmission order is set using successive beacon numbers, but the transmission order may be set using, for example, a predetermined beacon signal, that is, a beacon number of a predetermined number of intervals. For example, you may set a transmission order using the beacon number contained in three beacon signals.

On the other hand, although the encryption process may be performed on the status information transmitted from the station, the beacon signal transmitted from the coordinator is not encrypted. Therefore, the beacon signal is also transmitted to other groups of stations using the same frequency.

It is preferable that the coordinator in the other group analyzes the beacon signal and sets the signal transmission timing in the group to be different from the group which sent the beacon signal. For example, this can be realized by changing the value of IFS0 in the IFS vector value.

Here, consider a situation where two groups using the same frequency band form a network in the same environment. In the first group, as described above, it is assumed that IFS0 is set to 15 µsec and IFS offset is set to 7 µsec. The coordinator in the second group acquires the IFS vector value from the beacon signal from the first group and sets the IFS vector value in its own group. At this time, the IFS vector value is set so as not to overlap with the transmission timing of each station in the first group. For example, IFS0 is set to 19 μsec and IFS offset is set to 7 μsec. When four stations exist in each group, the transmission timing of each station in the first group is 15 µsec, 22 µsec, 29 µsec, and 36 µsec. On the other hand, the transmission timing of each station in the second group is 19 µsec, 26 µsec, 33 µsec, 40 µsec.

10 shows the transmission timing of each station in two groups. The transmission timing of each station in the first group is set to 15 µs, 22 µs, 29 µs, 36 µs, and the transmission timing of each station in the second group is set to 19 µs, 26 µs, 33 µs, and 40 µs. As a result, each station in each group performs signal transmission based on the transmission time from the other group. In this case, signals are alternately transmitted from each group. Signal conflicts between groups can be easily avoided by using a common IFS offset between a plurality of groups and changing IFS0.

Next, the self-controlled power saving mode in the second embodiment will be described.

Returning to Fig. 9, in the self-controlled power saving mode, in principle, each station receives a data signal from all other stations in the same group, and enters a power saving state based on the transmission of the data signal to another station. In the second embodiment, each station transmits game data once during the beacon interval, and the communication necessary for the beacon interval is completed by receiving the data signal from another station and transmitting the data signal by itself. Each station counts the number of data signals received from other stations, and makes a transition to the power saving state based on the counted number of data signals and the fact that they have transmitted the data signals. Also, since each station can autonomously enter a power saving state, the coordinator or the like in the communication system 1 does not have to directly manage power control of another station, for example.

According to the self-controlled power saving mode, power saving efficiency can be improved since the system quickly enters the power saving state after the completion of the transmission and reception of all necessary signals. Since unnecessary start-up periods can be eliminated in each station, and power control can be realized by a simple algorithm, it is suitable for practical use.

When power control is performed by this algorithm, if a station cannot receive a signal from another station, the station continues to wait for a signal from another station during the beacon interval, during which time Can't transition to state. Considering the frequency of occurrence of such a situation, this problem is not important, and the proportion of communication time is negligible and can be ignored. However, even in such a situation, it is desirable to increase the power saving efficiency if it can cope with a simple configuration.

11 is a timing chart showing a station operation for realizing a self-controlled power saving mode and a collision avoidance mode. 11 shows an example in which station C fails to receive a multicast data signal from station D. Stations A, B, and D receive signals from all other stations and transmit their own signals, so that they quickly enter a power saving state after receiving or transmitting signals from station D.

Each station has a function to monitor the communication status. In the example of FIG. 11, like the other stations, station C monitors the communication state and measures the period of no communication. The no-communication period is a period during which there is no transmission or reception of signals from stations in the same group. In addition, whether or not the signal is within the same group can be recognized by referring to the BSSID included in the signal. The station knows the maximum transmission timing that the stations in the group can take by station number and IFS vector value. For example, when the number of stations is 4, the IFS0 is 15 µsec and the IFS offset is 7 µsec, the maximum transmission timing is 36 µsec. Therefore, if the signal cannot be observed beyond the maximum transmission timing of 36 μsec from the time when the user sends a signal or receives a signal from another station, there is a possibility that the signal cannot be received even after waiting. high. Therefore, each station enters a power saving state when the non-communication period exceeds a predetermined time (T).

In the example of FIG. 11, the station C cannot receive the signal from the station D, and thus enters a power saving state after waiting for a predetermined time T. The predetermined time T is set to be longer than the longest time interval among the intervals of transmission timings determined for the stations constituting the group. In other words, the predetermined time T is set to a time obtained by adding some margin to the maximum transmission timing. For example, when the maximum transmission timing is 36 s, the predetermined time T may be set to 40 s.

The station in the second embodiment, that is, the functional block of the game machine 2 is as shown in FIG. 6 described in relation to the first embodiment. The communication function in the second embodiment is also implemented in the communication processing unit 4 by a CPU, a memory, a program loaded in the memory, and the like.

When the game machine 2 functions as a coordinator, the MAC unit 20 includes communication parameters in data frames transmitted by unicast communication for each of the game machines 2 in the same group. This allows all game machines 2 in the same group to share communication parameters. After all game machines 2 enter the game mode, the game machine 2, which is the coordinator, transmits a beacon signal including data elements for determining the transmission timing, i.e., beacon number, IBSS station number, IFS vector value. The timing at which the MAC unit 20 generates the beacon signal and the timing at which the PHY unit 26 transmits the beacon signal are controlled by the power / clock control unit 24.

FIG. 12 shows the details of the communication processing unit 4 shown in FIG. 6. Here, a configuration focusing on the communication function for realizing the self-controlled power saving mode and the collision avoidance mode in the second embodiment is shown. In the communication processing unit 4, the MAC unit 20 has a transmission control unit 50 and a reception control unit 52, and the PHY unit 26 has a transmitter 54 and a receiver 56. In the PHY unit 26, the transmitting unit 54 transmits a data signal to the other game machine 2, and the receiving unit 56 receives data signals from the other game machine 2. In the MAC unit 20, the transmission control unit 50 controls the transmission operation in the transmission unit 54, and the reception control unit 52 performs processing of the reception result in the reception unit 56 and the like.

In the game machine 2 serving as the coordinator, the transmission controller 50 generates a beacon signal. The transmission controller 50 includes the beacon number, the number of IBSS stations, and the IFS vector value in the beacon signal. The beacon number may be different in successive beacon signals, and may be read back at a predetermined cycle. In reality, because the number of bits representing the beacon number is finite, the beacon number is repeated periodically. Specifically, the transmission control unit 50 expresses the beacon number as 4 bits of data, for example, and assigns numbers from 0 to 15 periodically. Therefore, the beacon number is a data element having a different value for each notification signal. The number of IBSS stations is the number of stations constituting the group. As also described, the IFS vector value includes IFS0, which is data defining the reference time of transmission timing, and IFS offset, which determines the offset time from IFS0. In the game machine 2 serving as the coordinator, the transmitting unit 54 transmits the beacon signal generated by the transmitting control unit 50 at predetermined intervals.

In the game machine 2 other than the coordinator, in the collision avoidance mode, the receiver 56 receives a beacon signal including a data element for determining the transmission timing. The beacon signal is sent to the transmission control unit 50. The beacon signal contains the beacon number. The transmission controller 50 determines the transmission timing of its own data signal based on the data elements included in the beacon signal.

The transmission control unit 50 determines the transmission order in the group for each transmission based on the beacon number. Thereby, the transmission control part 50 can change the transmission order for every transmission, and can avoid the situation to which the transmission state of the specific game machine 2 worsens. Although the game machine 2 with a later transmission order is more likely to be unable to transmit, it is possible to achieve a fairness to the transmission priority of the game machine 2 by changing the transmission order.

The transmission control unit 50 also determines the transmission timing of the data signal using the beacon number and the station number assigned to the game machine 2. The station number is different for each game machine 2. By using a common equation for all game machines 2 to determine the transmission timing, it is possible to determine different transmission timings for each game machine by using the station number for one of the computational elements. This allows the game machine 2 to determine the transmission timing of its own data signal that does not overlap with the transmission timing of the data signal by the other game machines 2 forming the group. By eliminating the possibility of transmitting signals at the same time, smooth communication can be realized.

In the above, the method of determining the transmission timing in the game machine 2 which is not the coordinator has been described. In the game machine 2 which is the coordinator, the transmission control unit 50 holds the data elements included in the notification signal. Therefore, the transmission control part 50 can determine the transmission timing of its data signal as mentioned above based on the data element.

In addition, the transmission control unit 50 may determine the transmission timing in various forms. As one example, the transmission control unit 50 may set the transmission timing as the elapsed time after signal detection from another terminal device, and transmit the data signal when the transmission unit 54 has elapsed the time determined by the transmission timing.

In the self-controlled power saving mode, the receiver 56 receives a data signal from another game machine 2. The reception control part 52 counts the number of data signals which the reception part 56 received from the other game machine 2 in every beacon interval. The beacon signal includes a number of stations, and the reception controller 52 can grasp the number of other game machines 2 based on the number of stations. For example, when the number of stations is 4, it can be seen that there are three other game machines 2 except for itself.

For example, the reception controller 52 may specify the other game machine 2 that has transmitted the data signal based on the station number included in the data signal received from the other game machine 2. The station numbers of the other game machines 2 constituting the group are already known. For example, when the number of stations is 4 and its own station number is 1, the station numbers of the other three game machines 2 are 0, 2, and 3, respectively. The reception control unit 52 counts the data signal when the reception unit 56 receives a data signal from the other game machine 2 having the station number as 0, 2 or 3. In this example, the reception control unit 52 specifies the other game machine 2 based on the station number. For example, the other game machine 2 may be specified based on the MAC address. At this time, the reception control part 52 may table the station number, MAC address, etc. of the other game machine 2 in advance, and may determine whether it is the transmission from the other game machine 2 which should be counted by referring to the table.

The reception control unit 52 notifies the power / clock control unit 24 that the data signal is received from the other game machines 2 as a whole. The power / clock control unit 24 receives the notification and enters a power saving state.

Specifically, the reception control unit 52 sends a transition instruction to the power saving mode to the power / clock control unit 24. The power / clock control unit 24 stops the clock supply to the MAC unit 20 and the PHY unit 26 to stop the power consumption in the MAC unit 20 and the PHY unit 26. . As a result, the MAC unit 20 and the PHY unit 26 enter the sleep state. At this time, the power / clock control unit 24 sets the timer 22 to activate the MAC unit 20 and the PHY unit 26 after a predetermined time has elapsed from the time of entering the sleep state. This timer control is performed based on the value of TBTT. The timer 22 counts the pulses supplied from the clock unit 18 and supplies a wake signal to the power / clock control unit 24 after a predetermined time has elapsed. Upon receiving the wake signal, the power / clock control section 24 causes the MAC section 20 and the PHY section 26 to move to the activated state.

The reception control unit 52 monitors the communication state and notifies the power / clock control unit 24 of the fact that the radio communication period exceeds a predetermined time. This predetermined time is set to be the longest time interval among the intervals of the transmission timings determined by each of the game machines 2. The power / clock control unit 24 receives the notification and enters a power saving state. Specifically, the reception control unit 52 sends a transition instruction to the power saving mode to the power / clock control unit 24. The power / clock control unit 24 stops the clock supply to the MAC unit 20 and the PHY unit 26 to stop the power consumption in the MAC unit 20 and the PHY unit 26. .

13 shows the configuration of the transmission control unit 50. The transmission control unit 50 has a selection unit 60, a storage unit 62, and a data transmission unit 68. The selecting unit 60 classifies two types of data signals to be transmitted. Specifically, the data signal is selected from game data and other signals. The other signals may be, for example, control signals such as basic parameter values for performing communication. Hereinafter, signals other than game data are called control signals.

The sorted control signals and game data are supplied to the FIFO 64 and the game buffer 66 of the storage unit 62, respectively. The FIFO 64 is a first-in first-out memory, and has a function of sequentially storing the control signals supplied from the selection unit 60 and outputting them in the order of storage. . Since the transmission of the control signal is generally not required to be real-time, it can be output from the FIFO 64 at an appropriate timing to achieve a desired purpose of the control signal.

On the other hand, game buffer 66 is configured as an overwrite type memory. In particular, in game applications that require low latency, it is important to continuously transmit data in real time. If new data is generated when a transmission delay occurs, it is not necessary to send data that has been delayed. Therefore, the game buffer is overwritten and the new data is overwritten and stored to ensure real-time data.

The data stored in the FIFO 64 and the game buffer 66 are sent to the data sending unit 68. The data sending unit 68 sends the data sent from the FIFO 64 and the game buffer 66 to the transmitting unit 54. At this time, it is preferable to first transmit the data sent from the FIFO 64 to the transmission unit 54 on the condition that no problem occurs in the transmission of the game data. As this condition, for example, the data size of the control signal from the FIFO 64 is too large, and if it is sent as it is, the transmission of game data is interrupted. In this case, the data transmitter 68 may subdivide the control signal and send it to the transmitter 54. The reason why the data of the FIFO 64 is first transmitted to the transmission unit 54 is that transmission or reception of game data can be a trigger for transitioning to a power saving state in a frequently controlled power saving mode. By transmitting the control signal prior to the game data, the transmitting unit 54 can appropriately transmit the control signal even in the self-controlled power mode.

14 is a timing chart illustrating transmission of a control signal. In the example of FIG. 14, before the station C multicasts game data, the control signal is transmitted to the station D in unicast communication. Station C multicasts the game data after receiving the ACK from station D. In addition to the transmission of game data, the transmission timing determined in the collision avoidance mode is observed for the transmission of control signals.

In Example 2, the case where the collision avoidance mode and the self-controlled power saving mode are used together was demonstrated. As described above, efficient communication and power control can be realized by using these modes in combination, and each of them can be executed independently.

In the second embodiment, the case where the data signal (game data) is transmitted by multicast has been described, but it may be transmitted by broadcast. Even in the case of broadcast transmission, the transmission time can be shortened because it ends with one transmission operation to another station. In the second embodiment, the ad hoc mode of IEEE 802.11 has been described, but it is possible to realize the collision avoidance mode and the self-controlled power saving mode even in the infrastructure mode.

In the above, this invention was demonstrated based on the Example. It is to be understood by those skilled in the art that these embodiments are illustrative, and that various modifications are possible to the combinations of their respective components or respective processing processes, and that such modifications are also within the scope of the present invention. In the above embodiment, the case where low latency is mainly required and type 3 multicast communication is described has been described. However, the present invention is not only used for power saving control when low latency is required. Even when the type 2 communication system is adopted, it is possible to effectively use it.

In addition, you may implement | achieve the communication system 1 which used the power saving mode in Example 1 and the power saving mode in Example 2 together. That is, when the communication system 1 transmits a notification signal as one of the plurality of communication terminal devices as the power saving mode, the first power saving mode in which the plurality of communication terminal devices enter a sleep state and one communication terminal device communicate with each other. It is also possible to provide a second power saving mode that automatically enters a sleep state based on the number of data signals received from the terminal apparatus reaching a predetermined value, and these power saving modes may be selectively executed. The second power saving mode, that is, the self-controlling power saving mode, is characterized by power control, particularly in communications where low latency is required. Therefore, the communication system 1 which realizes high efficiency power saving by implementing the 2nd power saving mode for the game application with high real-time property, and the 1st power saving mode for the game application with relatively high real-time property is provided. can do. The degree of real-time property may be determined by the title or genre of the game, for example, the real-time property is determined based on the title or genre acquired by the application processing unit 12, and the real-time property is determined by the MAC unit 20. By transmitting, the MAC unit 20 may autonomously select and adopt the power saving mode described in the first or second embodiment.

In Embodiment 2, the self-controlled power saving mode in which the station enters the power saving state in principle provided that the station receives the data signal from all other stations in the group and also transmits the data signal has been described. In the above example, each station receives a data signal from each other station as a transition to the power saving state. For example, receiving a predetermined number of data signals from another station transitions to the power saving state. You may make it a condition. The predetermined number may take a plurality of values, for example, "3". In this case, the power saving state is provided on the condition that the user transmits one data signal while receiving three data signals from each of the other stations. You may move to.

This predetermined number may be notified to each station in advance as a communication parameter from the coordinator, or may be included in the beacon signal, for example. In either case, each station can grasp the number of data signals received from each other station as a transition condition to the power saving state, and execute the controlled power saving mode on the basis of the number. In the above, the case where the number of data signals received from one station is plural has been described, but the number of data signals transmitted by the station may be plural.

Each station may enter the power saving state based on either the number of transmissions of the data signal or the number of counts of the received data signal. In the communication environment, when each station in a group has a different role, for example, a station of a reception specialist may enter a power saving state based on the count of received data signals. In addition, if the station is a transmission specialist, it may enter a power saving state based on the number of times of transmission of the data signal.

1: communication system 2: game machine
3: game processor 4: communication processor
10: input unit 12: application processing unit
14: output 16: battery
18: clock portion 20: MAC portion
22: timer 24: power / clock control unit
26: PHY unit 50: transmission control unit
52: reception control unit 54: transmission unit
56: receiver 60: selector
62: memory 64: FIFO
66: game buffer 68: data transmission unit

Claims (14)

A transmitter for transmitting data,
A communication terminal apparatus having a transmission control section for controlling a transmission operation in the transmission section,
The transmission control unit,
A selection unit for classifying at least two types of data to be transmitted;
A storage unit having an overwrite type memory for storing predetermined types of data classified by the selecting unit and a FIFO type memory for storing other kinds of data classified by the selecting unit;
And a sending section for sending data stored in said storage section to said sending section. 2. The communication terminal apparatus according to claim 1, wherein the transmitting unit sends the overwritten data in the overwrite type memory to the transmitting unit. delete The communication terminal apparatus according to claim 1, wherein the communication terminal apparatus forms a group with one or more other communication terminal apparatuses and performs communication within the group.
A receiving unit which receives a notification signal including a data element for determining a transmission timing,
The transmission controller determines transmission timing of its own data based on the data elements included in the predetermined notification signal.
And a transmitting unit transmits data to another communication terminal device at a transmission timing determined by the transmission control unit. The communication terminal apparatus according to claim 4, wherein the transmission control unit sets the transmission order of data in the group for each data transmission based on data elements having different values for each of the notification signals. The communication terminal device according to claim 4, wherein the transmission control unit determines the transmission timing of data using the notification signal number included in the notification signal and the device number assigned to the communication terminal device. The transmission control unit according to claim 4, wherein the transmission control unit sets the transmission timing as an elapsed time after signal detection from another terminal device,
And a transmitting unit transmits data when the time determined by the transmission timing has elapsed after detecting a signal from another terminal apparatus. 5. The communication terminal device according to claim 4, wherein said transmission control unit determines the transmission timing of its own data so as not to overlap with the transmission timing of data by another communication terminal device. The communication terminal apparatus according to claim 1, wherein the communication terminal apparatus forms a group with one or more other communication terminal apparatuses and performs communication within the group.
The transmitter periodically transmits a predetermined notification signal including a data element having a different value for each notification signal.
And a transmission controller determines transmission timing of its own data based on data elements included in the notification signal. 10. The apparatus of claim 9, wherein the transmission control unit generates a notification signal including a notification signal number, information for determining a reference time of transmission timing, information for determining an offset time from the reference time, and a number of terminal devices forming a group. Communication terminal device, characterized in that. A transmitter for transmitting data,
A game machine provided with a transmission control unit for controlling a transmission operation in the transmission unit,
The transmission control unit,
A selection unit for classifying the data to be transmitted into game data and control data;
A storage unit having an overwrite memory for storing the game data and a FIFO type memory for storing the control data;
And a sending section for sending data stored in said storage section to said sending section. The memory device of claim 11, wherein the overwrite type memory stores the game data including status information of the game machine.
And the sending unit sends the game data overwritten in the overwrite type memory to the transmitting unit. delete 12. The game machine according to claim 11, wherein the transmitting unit gives the control data to the transmitting unit in preference to the game data.

Images