KR100404174B1 - Channel Multiplexing Method of Wireless Mobile Communication System - Google Patents

Abstract

In a wireless mobile communication system, especially when one wireless terminal service is intended to provide home wireless telephone service, office wireless telephone service and IS-95 CDMA communication service through one dual mode terminal, clean and reliable communication even in a mixed communication environment. The present invention relates to a multiplexing method of a forward CDMA channel for minimizing interference between channels so as to minimize interference between channels. In the transmission of a forward CDMA channel from a base station, a synchronization channel having a predetermined period is transmitted, and within a predetermined time after the synchronization channel is transmitted. It is characterized by transmitting a call channel having a certain period, and continuously transmit a pilot channel during the time when the synchronization channel and the call channel is not transmitted, according to the IS-95 CDMA communication with the home / office wireless telephone system Between channels that can be weighted in a mixed system situation Since the reduced relates to a channel multiplexing method in a wireless mobile communication system capable of communicating with a clean and reliable.

Description

Channel Multiplexing Method of Wireless Mobile Communication System

The present invention relates to a wireless mobile communication system, and particularly to provide a home wireless telephone service, an office wireless telephone service, and an IS-95 CDMA communication service through one dual mode terminal, even in a mixed communication environment. The present invention relates to a multiplexing method of a forward CDMA channel that minimizes interference between channels to enable reliable and reliable communication.

Generally, various types of services are already provided, such as home wireless telephone service, office wireless telephone service using wireless private branch exchange (PBX), and IS-95 CDMA communication service. Each service may be provided through a terminal for each service that is independent and can provide only its own service.

Accordingly, partial efforts are being made to receive all these services through one terminal, and home wireless telephone service, office wireless telephone service and IS-95 CDMA communication service using one dual mode terminal. When you want to provide a different wireless interface and wireless access protocol for each service must be used, the inefficiency of implementing a separate wireless interface for the selection and acquisition of the service to be used or switching to another service among the service and the user separately Efforts have been made to eliminate the inconvenience of having to order a service switch.

Accordingly, in order to service these services using a single terminal, it is necessary to maximize the commonality of the wireless interface and wireless access protocol for each service of the home wireless telephone service, the office wireless telephone service, and the CDMA public cellular service. The terminal to be used should automatically detect each service and access to the selected service.

1 is a diagram illustrating a synchronization channel and a call channel synchronized with a pilot channel of an IS-95 CDMA system according to the prior art.

The forward CDMA channel of the base station includes a pilot channel 1, a call channel (not shown), a synchronization channel (2, 2), and a call channel (4), which will be described in detail later.

The pilot channel 1 is an unmodulated spread spectrum signal used by a terminal in the base station's service area to synchronize, and the base station always transmits the pilot channel 1 through all forward CDMA channels in an active state. In addition, the terminal distinguishes the pilot channel 1 using 64 PN chips transmitted from the base station and simultaneously extracts the PN code from the subsequent 256 PN chips.

The extracted PN code is used to decode the sync channel (2,3) message. The PN chip transfer rate is 1.2288Mcps and the time taken for generating one PN chip is about 0.81μs.

Each pilot channel 1 is distinguished from offset index-0 to offset index-511, and 512 pilot PN sequences according to this offset index are defined by offset values from the 0-offset pilot PN sequence. For the 0-offset pilot PN sequence, the starting point of the sequence is the starting point every even second based on the base station transmission time. The starting point of the 0-offset pilot PN sequence is the output value of the previous 15 offset pilot PN sequences is '0'. Is defined as

The pilot PN sequence offset can have 512 unique values, and the offset value for a given pilot PN sequence from a 0-pilot PN sequence is equal to 64 times each offset index (chipwise). For example, if the offset index of the pilot PN sequence is 15, then the pilot PN sequence offset is 15 x 64 = 960 PN chips, and the pilot PN sequence starts after 781.25 μs from the start of every even time second based on the base station transmission time.

2 is a diagram illustrating a structure of a synchronization channel of an IS-95 CDMA system according to the prior art.

When the transmission device in the service area of the base station synchronization channel is used to match the initial time synchronization with a base station is transmitted to the transmission rate of 1200bps, the frame length of the synchronization channel is 26.666ms, and the timer T _1b (1.28 s) is terminated do.

As shown in FIG. 2, the structure of the synchronization channel is composed of 80 ms super frames 10 and 11, and each super frame 10 and 11 is divided into three 26.666 ms synchronization channel frames 20 to 25. Lose. The first bit of each sync channel frame 20-25 is the Start of Message (SOM) bits 30-35, and the remaining bits in each sync channel frame 20-25, except for the SOM bits 30-35, are synchronized. It consists of channel frame bodies 40-45.

The sync channel message capsule 50 is comprised of a sync channel message 51 and padding bits 52 which can be assigned one or several bits, which is a 8-bit length field. (MSG_LENGTH) 60, a sync channel message body field 61, and a CRC field 62.

Here, the sync channel message capsule 50 starts with the first bit of the first sync channel frame body 40 of the sync channel superframe 10, 11.

The base station sets the SOM bit 30 before the start of the sync channel message capsule 50 to '1' and the remaining SOM bits 31 to 35 to '0' to continue the sync channel message 51. Are transmitted through the sync channel frame bodies 40 to 45. The base station also inserts padding bits 52 from the end of each sync channel message capsule 50 to the beginning of the next SOM bit (not shown) of the next sync channel super frame (not shown). At this time, the sync channel message capsule 50 starts only in the first sync channel frame 20 of each sync channel super frame 10,11, and the padding bit 52 is a total sync channel message 51 and padding bit ( The sum of 52) is added to be an integer multiple of 93, at which time the padding bits 52 added are all set to '0'.

3 is a view showing the structure of a call channel of the IS-95 CDMA system according to the prior art.

The call channel transmitting the system additional information and the mobile station specification message of the base station at a rate of 4800bps or 9600 bps has a frame length of 20ms, and the periodic message of the call channel is transmitted when the timer T _1b (1.28 s) ends.

The call channel is divided per 80ms slots, and each slot is divided into 2048 slot periods (163.84 seconds) selected as the maximum slot period. Each maximum slot period starts at a frame with a remainder of 0 when the system time in 80 ms is divided by 2048 slot periods, and each call channel slot 70 to 72 of the maximum slot period is numbered from 0 to 2047.

A 20 ms call channel frame (not shown) is divided into 10 ms call channel half frames 80-84, with the first bit of each call channel half frame 80-84 being synchronised. Capsule Indicator) bits 90 to 94.

The call channel message capsules 111 to 114 are composed of call channel messages 121 to 123 and padding bits 131 and 132 to which one or several bits can be assigned, and the call channel messages 121 to 123 are 8 bits. Is composed of a length field (MSG_LENGTH) 141, a call channel message body field 142, and a CRC field 143.

The length field (MSG_LENGTH) 141 of the call channel messages 121 to 123 indicates the length of the call channel messages 121 to 123 in octets, the length being the length field (MSG_LENGTH) 141 and the call channel message. It includes a body field 142 and a CRC field 143.

The base station may send synchronous or asynchronous call channel message capsules 111-114, where the synchronized call channel message capsules 111-114 begin at the second bit of the call channel half frame 80-84, and are asynchronous. The called channel message capsules 111-114 are started immediately after the preceding call channel messages 121-123 to be transmitted.

In detail, if more than 8 bits remain after the call channel messages 121 to 123 until the next sync capsule identification bits 90 to 94 are started, the base station makes an asynchronous call after the call channel messages 121 to 123. Channel messages 121-123 can be sent immediately. At this time, the base station does not include the padding bits 131 and 132 in the call channel messages 121 to 123 transmitted after the asynchronous call channel messages 121 to 123. However, less than 8 bits remain until the next sync capsule identification bits 90-94 begin after the call channel messages 121-123, or asynchronous call channel message capsules 111-111 to be sent after the call channel message capsules 111-114. If there is no 114, the base station includes enough padding bits 131, 132 up to the next sync capsule identification bits 90-94 and after the sync capsule identification bits 90-94, synchronize the call channel message capsules 111-114. Send immediately. At this time, all padding bits 131 and 132 are set to '0', and if the call channel message capsules 111 to 114 follow after the sync capsule identification bits 90 to 94, the base station sends the sync capsule identification bits 90 to 94. Set to '1', otherwise set to '0'. In addition, the first message starting at each calling channel slot 70-72 is sent to a sync channel message capsule (not shown).

4 is a diagram illustrating a structure of a forward CDMA channel of an IS-95 CDMA system according to the prior art.

Referring to FIG. 4, the allocation of code channels transmitted from a base station is shown. The 64 code channels allocated include one pilot channel 210, one synchronization channel 220, seven call channels 230, 240, and 55. There are two communication channels 250-290.

The pilot channel 210 is transmitted continuously and the periodic messages of the sync channel 220 and the call channel 230, 240 are broadcast over each forward CDMA channel 200 after the T _1b (1.28s) timer expires. (Broadcasting)

As such, the mobile station for obtaining the forward CDMA channel 200 transmitted from the base station must acquire each CDMA channel 200 before the timers listed below expire.

First, in the case of the pilot channel 210, the timer T20m is used, and the pilot channel 210 should be acquired within a maximum of 15 seconds.

Next, the timer T21m is used for the sync channel 220, and within 1 second, the mobile station should analyze the sync channel message (not shown) of the base station to obtain the system time.

Finally, two timers are used for the calling channels 230 and 240. When the mobile station is in idle state, the timer must be acquired within 3 seconds using the timer T30m. When the mobile station is in system connection, the timer T40m is used. To acquire call channels 230,240 within one second.

However, CDMA / CT duplex is already available in homes and offices that already use wireless telephony services so that one dual-mode terminal can provide both home wireless telephone service, office wireless telephone service, and IS-95 CDMA-based communication services using a single dual-mode terminal. If a base station for a mode service is provided, the service area of the home / office base station and the service area of the CDMA / CT dual mode base station may overlap.

Since the overlap of the base station service area causes interference between base stations, it is a factor that cannot provide a high quality call reliably, and thus, pilot channel, synchronization channel, and call among the forward CDMA channels according to the related art described above. Channel multiplexing is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and provides a base station service area generated when one dual mode terminal is used to provide both home wireless telephone service, office wireless telephone service, and IS-95 CDMA communication service. An object of the present invention is to provide a channel multiplexing method of a wireless mobile communication system in which a pilot channel, a synchronization channel, and a call channel are multiplexed among forward CDMA channels into one in order to eliminate interference due to the superposition of the CDMA channels.

A feature of a channel multiplexing method of a wireless mobile communication system according to the present invention for achieving the above object is that, in transmitting a forward CDMA channel from a base station, a synchronization channel having a predetermined period is transmitted, and in advance after the synchronization channel is transmitted. A call channel having a predetermined period is transmitted within a set time, and the pilot channel is continuously transmitted during a time when the sync channel and the call channel are not transmitted.

Preferably, the synchronization channel and the call channel are transmitted at respective periods by their periodic timers, and the call channel is transmitted as the periodic timer of the synchronization channel expires, and the synchronization channel is Sent as the periodic timer expires.

In addition, the sync channel, the call channel, and the pilot channel are transmitted at the same transmission rate, and the call channel having a predetermined period is transmitted within 1 second after the sync channel is transmitted.

1 is a view showing the structure of a pilot channel of the IS-95 CDMA system according to the prior art.

2 is a diagram illustrating a synchronization channel and a call channel synchronized with a pilot channel in an IS-95 CDMA system according to the prior art.

3 shows the structure of a call channel in an IS-95 CDMA system according to the prior art;

4 is a diagram illustrating a structure of a forward CDMA channel of an IS-95 CDMA system according to the prior art.

5 is a block diagram showing the conceptual structure of a radio protocol of a system supporting IS-95 CDMA / CT dual mode according to the present invention;

6 is a diagram illustrating a message length for each channel period for channel multiplexing according to the present invention.

7 illustrates channel periods in a multiplexed channel according to the present invention.

Explanation of symbols for main parts of the drawings

10: management layer 20: application layer

30: network layer 31: data link layer

40: physical layer

Hereinafter, a preferred embodiment of a multiplexing method of a forward CDMA channel according to the present invention will be described with reference to the accompanying drawings.

5 is a block diagram illustrating a conceptual structure of a radio protocol of a system supporting IS-95 CDMA / CT dual mode according to the present invention.

As shown in FIG. 5, the wireless protocol according to the present invention includes a management layer 440 that manages a physical layer 400, a data link layer 410, a network layer 420, an application layer 430, and overall protocol layers. This wireless protocol is applied equally to the terminal side and the base station side.

The physical layer 400 is a layer that allows a message to be transmitted and received through a generally defined physical channel, and the data link layer 410 defined as a sub-layer of the network layer 420 is a network layer ( As a layer to ensure reliable message transmission with respect to 420, each state of the data link layer 410 exists as a substate of all states except when the network layer 420 is null. The network layer 420 performs connection and disconnection of calls through signaling messages, manages radio resources, and provides mobility.

Each layer of these protocols has an interface for passing primitives between its upper and lower layers. Among them, the management layer 440 has interfaces to all layers, so it can carry primitives between two layers having no interface. It is responsible for the overall management of the protocol, including the management of primitives and timers that are not related to message transmission, and does not have a specific state. In particular, the management layer of the terminal side transmits and receives events related to service mode switching with the network layer 420 and the physical layer 400, and manages information related to service mode switching, so that the network layer 420 and the physical layer 400 serve the service. Properly operate according to the mode switch.

Here, the radio access protocol layers of all service modes to be switched have the same state, and perform a different function for each service mode, and if a service mode switching condition is generated according to the priority determined by the management layer 440. Select and decide which service mode you are using and which one you will use next.

Each system used in the present invention has a respective initialization state for each service mode, and the initialization state of each mode is defined as the same substate as the IS-95 CDMA system.

There are some differences in the functions of the substates for each service mode. The main functions of each substate are as follows.

The system decision substate determines one of the dual mode IS-95 CDMA systems to be used and the CDMA channel of the selected home wireless telephone service, office wireless telephone service, and IS-95 CDMA communication service mode.

The pilot channel acquisition substate searches for a pilot channel of a corresponding system mode tuned to the determined CDMA channel and acquires a pilot channel. When the pilot channel acquisition timer expires, the system decision substate of the service mode to be selected next according to the priority is given. To transition.

In the sync channel acquisition sub-state, a sync channel message is received to obtain system information and timing information. When the home wireless telephone service and the office wireless telephone service are selected, the terminal stores the mobile station identification number (MIN _CT) stored therein. A base station that broadcasts the same identification information (SID / NID) as Number is identified as its corresponding base station. If the synchronization channel acquisition timer expires, the system transitions to the system decision substate of the service mode to be selected next according to the priority.

The time change sub-state changes the terminal time according to the system time according to the information of the received sync channel message, determines the call channel of the corresponding service mode, and then transitions to the idle state. Here, the idle state is finally determined by the service mode selected as the last step of the initialization procedure, and the terminal may perform call processing procedures such as origination and incoming calls in the idle state, which is determined as the service mode of the IS-95 CDMA system. In this case, a timer is periodically set for measuring the power strength of the pilot channel of the home wireless telephone service and the office wireless telephone service.

Meanwhile, the dual mode terminal having the above-mentioned wireless protocol selects an available service mode according to the stored priority. After the service mode is selected, the dual mode terminal is operated in the selected service mode until the service mode conversion condition or the user's request is made. do.

In providing such a dual mode wireless communication service, a home / office base station having a wireless protocol may be installed in an arbitrary place so that mutual interference between the home / office base station and interference with the IS-95 CDMA system may be avoided. In order to reduce the number of forward CDMA channels, the pilot, sync, and call channels must be multiplexed and transmitted. At this time, the periodic message of each channel to be transmitted should be transmitted only when the corresponding timers defined differently from each other end, and maximize the commonality by using similar procedures as in the existing IS-95 CDMA communication system. To have

When the channels for the dual mode wireless communication service are multiplexed, the transmission speed of each channel does not need to be different as in the IS-95 CDMA communication system, so that the calling channel speed (4800 or 9600 bps) Enable channel multiplexing to be effective.

6 is a diagram illustrating a message length for each channel period for channel multiplexing according to the present invention.

Referring to FIG. 6, as described above, a terminal used in an IS-95 CDMA communication system uses 64 PN chips for identification of a pilot and a PN code for decoding a message of a synchronization channel 500. 256 PN chips were further used for the extraction of. However, since the dual mode terminal used in the present invention stores both the pilot channel 520 and the PN code used in the home and office base stations, it is not necessary to receive an additional 256 PN chips.

In addition, since the transmission time per PN chip in the base station takes about 0.81 μs, it takes about 52.083 μs to transmit the 64 PN chip, but the pilot channel is used for synchronization between the terminal and the base station. Since the channel is a reference, the present invention transmits it as continuously as possible.

In addition, in the dual mode system, the message SYNC_MSG of the synchronization channel 500 is configured with a maximum message size of 144 bits (170 bits in the case of an IS-95 message), and if the transmission rate of the channel is 9600 bps, one frame ( It is possible to transmit 256 bits in 26.67ms), so only one frame may be used to transmit 170 bits. If the transmission rate of the channel is 4800 bps, 128 bits can be transmitted at 26.67 ms, so two frames must be transmitted continuously.

Finally, in the case of the call channel 510, the system parameter message (SYS_PAR_MSG) consisting of 144 bits (226 bits in the case of the IS-95 message) is the maximum message, and the transmission of 192 bits or 96 bits in one frame (20ms) is performed. It is possible. If the channel's transmission rate is 9600 bps, 192 bits can be transmitted in 20ms, so system parameter messages can be transmitted using two frames.If the channel's transmission rate is 4800 bps, 96 bits can be transmitted in 20ms. A 20ms frame transmits three times in succession.

Therefore, when looking at the message transmission time of each channel based on the transmission rate of 4800 bps, the sync channel 500 takes 53.34ms because 2 frames are used at the rate of 4800 bps for maximum message transmission. In the case of the call channel 510, since 3 frames are transmitted at a rate of 4800 bps, it takes 60 ms. In the case of the pilot channel 520, the messages of the sync channel 500 and the call channel 510 are transmitted continuously while not being transmitted.

As described above, in order to determine the channel period by referring to the transmission time for each channel, the channel acquisition time by each corresponding timer that the terminal has to acquire each channel normally should be considered.

Unlike the conventional IS-95 CDMA communication system, the channel acquisition time should be set to a minimum in accordance with the environment of a dual mode system multiplexed with a single channel. An important consideration in determining the period of a message is important here. After acquiring the sync channel 500, it may take 1 second to acquire the call channel 510.

In addition, the pilot channel 520 has a 15-second acquisition time because the signal is transmitted almost continuously, and in the case of the sync channel 500, the channel should be acquired within 3 seconds, and thus the channel acquisition time having the smallest time constraint. This must be considered.

7 illustrates channel periods in a multiplexed channel according to the present invention.

Referring to FIG. 7, first, the periodic timers T21b 600 of the synchronization channel are set to 2 seconds, and the periodic timers T30b 700 of the call channel are set to 2 seconds, and the periodic timers 600 and 700 of each channel are terminated. Only when the base station transmits the message according to the terminated channel timer (600,700).

In addition, in the case of a pilot channel, transmission is continuously performed while a sync channel message or a call channel message is not transmitted. By this method, interference between the base station of the dual mode system and the neighboring base station of the home or office can be reduced, and the interface with the IS-95 CDMA type communication system is provided as much as possible.

As described above, according to the channel multiplexing method of the wireless mobile communication system according to the present invention, an environment in which a home wireless telephone service, an office wireless telephone service, and an IS-95 CDMA communication service are provided through one dual mode terminal, That is, since interference between channels that can be increased in a situation where a home / office wireless telephone system and an IS-95 CDMA communication system are mixed, there is an effect that clean and reliable communication can be performed. In addition, since the multiplexed channel has the same air interface as possible with the existing IS-95 CDMA communication system, it is expected that the dual-mode terminal and the base station can be produced inexpensively and easily.

Claims (4)

Transmitting a forward CDMA channel from a base station, transmitting a synchronization channel having a predetermined period at a corresponding period by its timer; Transmitting a call channel having a certain period within a preset time after the synchronization channel is transmitted at each corresponding period by its timer; And continuously transmitting a pilot channel during a time when the sync channel and the call channel are not transmitted. The channel multiplexing of claim 1, wherein the call channel is transmitted as the periodic timer of the synchronization channel ends, and the synchronization channel is transmitted when the periodic timer of the call channel expires. Way. The channel multiplexing method of claim 1, wherein the synchronization channel, the call channel, and the pilot channel are transmitted at the same transmission rate. The channel multiplexing method of claim 1, wherein the call channel having a predetermined period is transmitted within one second after the synchronization channel is transmitted.