KR100541641B1 - Method of allocating optimized content access period in highrate wireless personal access network - Google Patents

Abstract

The present invention is divided into sparse environment and dense environment according to the density of devices (DEVs) in a high speed Wireless Personal Area Network (WPAN) and optimized for each content access period duration It is related to a method for reconstructing a superframe to assign a).

To this end, a method for allocating a CAP interval according to the present invention includes collecting a time and information required by a PNC (Piconet Coordinator) to process resources for devices, and integrating a DEV with a PNC. The step of determining and performing the algorithm for classifying the optimized CAP interval corresponding to the sparse environment and dense environment according to the determination result.

Wireless Personal Area Network (WPAN), DEV (device), Superframe (Superframe), Icon Coordinator (PNC), Contention Access Period (CAP), Channel Time Allocation Period (CTAP), Carrier Sense Multiple Access / Collision Avoidance)

Description

METHODS OF ALLOCATING OPTIMIZED CONTENT ACCESS PERIOD IN HIGHRATE WIRELESS PERSONAL ACCESS NETWORK}

1 schematically illustrates a conventional 802.15.3 piconet configuration.

Figure 2 shows the format of a conventional 802.15.3 piconet superframe.

3 illustrates a beacon frame format of a conventional 802.15.3 piconet superframe.

4A illustrates a superframe format in an initial mode according to an embodiment of the present invention.

4B illustrates a superframe format in a normal mode according to an embodiment of the present invention.

4C illustrates a superframe format in an aggressive mode according to an embodiment of the present invention.

5 schematically illustrates a method for allocating a CAP interval for implementing an embodiment of the present invention.

6 is a flowchart illustrating a process of a normal mode in detail according to an embodiment of the present invention.

7 is a flowchart illustrating a process of an advanced mode according to an embodiment of the present invention in detail.

8A is a flowchart illustrating a method of allocating a DCAP according to an embodiment of the present invention.

8B is a flowchart illustrating another method for allocating a DCAP according to an embodiment of the present invention.

The present invention relates to a method for allocating an optimized content access period (CAP) interval in a high speed wireless personal area network (WPAN), and more particularly sparse according to the density of devices (DEVs). The present invention relates to a method of reconfiguring a superframe in order to classify an environment and a dense environment and allocate an optimized CAP section according to each of them.

As digital technology develops, we can easily access various digital products around us and enjoy convenient life through digital products. Various digital products, such as DVD players, cable STBs (SeTop Boxes), Digital Video Cassette Recorders (DVCRs), Digital TVs (DTVs), or Personal Computers (PCs), are currently available or under development. These digital products can be used alone, but can be connected to one network. Such a network is called a personal area network (hereinafter referred to as a PAN). In the past, PANs were mainly constructed by wired networks such as cables, but wireless LANs are gradually increasing as wireless communication technologies are developed.

As shown in FIG. 1, a wireless Ad Hoc communication system that allows multiple independent data devices (DEVs) to communicate with each other is referred to as a piconet. All devices on the wireless PAN can access the Wireless Medium (WM) according to the information provided by the PicoNet Coordinator (hereinafter referred to as PNC). The information is broadcast through a beacon, and one piconet is determined by a PNID (Peanet ID) and BSID (Beacon Source ID) defined by the PNC.

According to the IEEE 802.15.3 specification, theoretically, 256 devices (DEVs) can be connected to one PNC to communicate with each other. However, considering the actual communication distance and communication environment, about 8 devices can be connected to one PNC. The most efficient communication takes place when connected.

As illustrated in FIG. 2, timing in an 802.15.3 piconet superframe is determined by a beacon, a contention access period (CAP), and a channel time allocation period (CTAP). It consists of three parts. The beacon contains various information needed for timing allocation and the PNC to manage all devices, such as indicating the CAP end time as illustrated in FIG. 3.

The CAP section is used to send and receive asynchronous data and commands. The CTAP section consists of Management Channel Time Allocation (MCTA) and Channel Time Allocation (CTA), which are used for commands, isochronous streams, and asynchronous data connections.

The length of the CAP section is determined by the PNC and communicates with the DEV in the piconet via a beacon. Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) is used for medium access in the CAP section of the 802.15.3 piconet. During the CAP period, devices reserve the necessary resources and receive channels from the PNC through the beacons. In addition, a small amount of data can be communicated in the CAP interval without being allocated. However, the PNC can replace the functions provided during the CAP section in the MCTA section, except that all devices are required to use the CAP section in the 2.4 GHz physical layer (hereinafter referred to as PHY).

As described above, since there is no algorithm optimized for determining the CAP interval by contention in the 802.15.3 piconet, it may operate inefficiently. When a competition occurs to determine the CAP interval, a backoff algorithm is used.If a request comes up from the devices at the same time even when the channel is empty, the competition is considered to have occurred. Increasing the window size causes a delay in processing time. And since there is no constant method for constructing the piconet network, when a small number of devices communicate in one piconet area, the frame size cannot be effectively used. That is, changing the size of a superframe delays the processing of the devices because at least four beacons must be broadcast to all devices to change the size of one frame.

The present invention has been made to solve the above problems, sparse environment or dense environment varying the density depending on the number of devices for efficient channel allocation of devices that support high speed in WPAN The technical problem is to provide a method for reconstructing a superframe using an efficient CAP allocation mechanism.

In addition, in the method of reconstructing the superframe, during the contention-based CAP period, the devices are reserved for the necessary resources (resource) and the channel is allocated from the PNC in the present invention mechanism for allocating an optimized CAP interval Optimize the time allocation for other devices that require time allocation in the CAP interval by adding a DCAP (Dynamic Contention Access Period) followed by a superframe configuration consisting of the original beacon, CAP and CTAP. Let it be the technical problem.

In order to achieve the above object, a method for allocating a CAP interval according to an embodiment of the present invention is provided by a wireless personal area network coordinator from devices constituting a wireless personal area network (hereinafter referred to as WPAN). Collecting time and information necessary to process the resource, generating a superframe including an CAP interval adaptively allocated according to the number of devices coupled to the WPAN, and broadcasting the superframe. Is done.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4A illustrates a superframe format in an initial mode proposed by the present invention. The superframe in this mode consists only of beacons and CAPs.

That is, in the method of allocating the CAP interval here, the remaining time except for the beacon in the entire frame is allocated to the CAP interval to collect time and information required for devices to process resources.

4b illustrates a superframe format in a normal mode proposed in the present invention. The superframe configuration in this mode is composed of beacons, CAPs and CTAPs, and is configured in the conventional standard mode currently supported by 802.15.3 to support communication with general devices.

4C illustrates a superframe format in an aggressive mode proposed in the present invention. The superframe configuration in this mode consists of beacons, CAPs, CTAPs, and DCAPs, and the DCAP interval is allocated to the remaining slots using CAPs and CTAPs in a sparse environment with low DEV density. In the DCAP section, only devices that need to compete compete and receive CTAs in the next superframe, or process simple data by dividing the CAPs and CTAs in the DCAP.

5 schematically illustrates a method for allocating a CAP interval for implementing an embodiment of the present invention. First, the initial mode 510 of the present invention is performed. The user then selects either an initial mode or a normal mode 531 or an aggressive mode 532. In the initial mode, as shown in FIG. 4A, a beacon comes and all remaining sections except the beacon are allocated to the CAP to find out what commands or stream data the devices want to send in the piconet area. Therefore, all devices that need resource allocation in the CAP section except for the beacon, when they send a stream request command, receive the time they need as one primitive. DesiredNumTUs { Request} and MinNumTUs (the minimum amount of time required to perform data), so the commanded PNC knows how much channel time each device needs.

6 is a flowchart illustrating a process of a normal mode in detail according to an embodiment of the present invention. The PNC sets the CAP section after the beacon (S610). Next, the devices DEVs contention and transmit a channel time request command to the PNC (S620). Devices that have already requested channel allocation from the PNC receive a channel time response command (S630). As shown in FIG. 4B, two devices transmit a channel time request command to the PNC during a CAP period, receive a channel, and transmit data during a CTAP period (S640). However, in the normal mode, if the time unit (TU) required by the devices is smaller than the size of the super frame, there is no method that can be used again in the normal mode even if any part of the frame remains.

7 is a flowchart illustrating a process of an aggressive mode according to an embodiment of the present invention in detail. First, it is determined whether the device integration degree is less than or equal to the threshold value 4 (S710). If the integration degree is 4 or less, a CAP interval is calculated using a CAP mechanism suitable for a rare environment (S721). Defining the elements needed to calculate this requires that aSlotTime (the time it takes for a device or PNC to send and receive requests / responses), Backoff Interframe Space (BIFS), Backoff time, and data ( A request / response command or a small amount of asynchronous data), a short interframe space (SIFS), and an acknowledgment (ACK). The above elements can be used to define aSlotTime (aSlotTime = BIFS + Backoff Time + Command Frame + SIFS + ACK). The CAP interval in the environment of sparse device integration is defined as the product of the aSlotTime and the number of channel request devices. Calculate the CAP interval by the proposed method and give the CTAP from the end of the CAP interval, it is determined whether the time required from the devices is smaller than the size of the remaining frame (S730). If the determination result is smaller than the size of the remaining frame, the DCAP is allocated before the beacon of the next super frame comes (S740). As noted above, the existing IEEE 802.15.3 specification is a competitive device, or if a new device wants to enter the PNC, it waits until the current frame ends and the next frame begins, and then competes. Data could be sent at the time the assignment was received. However, using the DCAP, without waiting until the next frame can request a channel allocation time to send another command or send small data as if the assigned CTAP is finished, and the requested PNC has its own When CTAP starts without competing in the next frame through the channel time response command to the device requesting the channel for the remaining period by checking the resource, the data can be processed at the allocated time.

If the device density is greater than or equal to the threshold value 4, a CAP interval is calculated using a CAP mechanism suitable for a dense environment (S722). In this case, if the previous CAP duration is used as it is, a collision occurs because the number of devices that join the PNC increases. A new CAP section is proposed to eliminate collisions and provide an appropriate CAP section. Define the elements needed to calculate this: aSlotTime (the minimum time required for one DEV to send a command frame one or more times through channel contention), collision fragments {collision fragment = k * collision frequency} , k is the collision weight. K finds an appropriate value by experiment and generates a reference table. Using the above elements, a CAP section (CAP section = previous CAP section + aSlotTime * collision fragment) corresponding to a dense environment may be defined.

8A is a flowchart illustrating a method of allocating a DCAP according to an embodiment of the present invention. This is to process the work to be done in the CAP section of the next frame one frame before the CAP section. The PNC generates a control frame and transmits it to each device (S810). Or, since each device knows when another device is being used through the beacon broadcasted by the PNC and when the CAP ends, the devices parse information at the end of the CTAP (S810). Next, devices already know by broadcasting the end of the CTA, so devices that need or need to associate can compete with asynchronous data or commands to see and send the broadcasted information. Create a CAP interval (S820). In this way, commands or asynchronous data can be received in the same frame, thereby reducing the CAP interval of the next superframe and distributing more CTAs.

8B is a flowchart illustrating another method for allocating a DCAP according to an embodiment of the present invention. By creating a DCAP section with only devices that need to compete, it creates a section that can handle a small amount of data by allocating CAPs and CTAs. That is, devices that need to be allocated time generate a frame for the required time and request the PNC (S910). Next, if it is determined that the received PNC can process during the DCAP period, the remaining time is allocated among the requested devices (S920).

As described above, according to the present invention, an efficient channel of devices supporting high speed in a rare environment or a dense environment where device density is low by changing the configuration of a superframe field in a wireless personal area network (WPAN) This has the effect of providing an assignment.

According to the present invention, since the DCAP interval can be generated in the remaining frame by calculating the CAP interval, and commands or asynchronous data can be received in the same frame, the CAP interval of the next superframe can be reduced and more CTAs can be distributed, thus requiring time allocation. This has the effect of optimizing time allocation for other devices. In addition, in order to prevent collisions in a dense environment, since the fragments are used by fragmenting, the collision time is minimized.

Claims (9)

Collecting, by the wireless personal area network coordinator, the time and information needed to process resources from devices that make up a Wireless Personal Area Network (WPAN); Generating a superframe including an CAP interval adaptively allocated according to the number of devices coupled to the WPAN; And Broadcasting the superframe; and assigning an optimized CAP interval in a fast WPAN. The method of claim 1, Generating the superframe Calculating the CAP interval when the number of devices is equal to or less than a predetermined value; And Creating a superframe including a dynamic contention access period of the devices if the time required to process the resource requested from the devices is less than the remaining time of the superframe; Method for allocating optimized CAP interval in WPAN. The method of claim 2, The step of calculating the CAP interval A method for allocating an optimized CAP interval in a fast WPAN comprising calculating the product of aSlotTime and the number of channel request devices. The method of claim 3, wherein The aSlotTime is A method for allocating an optimized CAP interval in a fast WPAN, which is a value calculated according to Equation BIFS + Backoff Time + Command Frame + SIFS + ACK. The method of claim 2, The dynamic competition approach section A method for allocating an optimized CAP interval in a fast WPAN that is a CAP interval for the devices. The method of claim 2, The dynamic competition approach section Method for allocating the optimized CAP interval in the high-speed WPAN consisting of a CAP interval and a Channel Time Allocation Period (hereinafter referred to as CTAP) for the devices. The method of claim 1, Generating the superframe Calculating the CAP interval when the number of devices is greater than a predetermined value. The method of claim 7, wherein The step of calculating the CAP interval A method for allocating an optimized CAP interval in a fast WPAN comprising calculating according to the CAP interval + aSlotTime * collision fragment of the previous superframe. The method of claim 8, The collision fragment is A method for allocating an optimized CAP interval in a fast WPAN calculated by multiplying the collision value (k), which is an experimental value.

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