JP2010062634A - Radio communication base station system, and radio communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means which automatically decides message transmission times and performs transmissions according to change of radio quality. <P>SOLUTION: A base station has a radio quality measurement unit which measures radio quality between the base station itself and a terminal, and a message transmitting/receiving unit which has a function to transmit messages multiple times according to the radio quality. The message transmitting/receiving unit analyzes the radio quality using the data measured by the radio quality measurement unit, and calculates transmission times of the messages. Moreover, upon transmitting messages multiple times, it transmits making sequence numbers in headers attached to the messages as the same. The radio quality measurement unit measures radio wave quality itself between the terminal and the base station, or data necessary for deciding the quality of the radio wave, and transmits the data to the message transmitting/receiving unit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radio communication base station system and a radio communication terminal, and more particularly to a radio communication base station system and a radio communication terminal related to transmission of a signaling message.

  For messages communicated between a radio communication base station (hereinafter referred to as a base station) and a radio communication terminal (hereinafter referred to as a terminal) in a cellular phone system, traffic data for voice and data communication, and for controlling a call There are two types of signaling messages. These messages play an important role in the mobile phone system, and if a message is lost, the service is affected. Therefore, the cellular phone system takes measures to prevent message loss. In the cdma2000 1xEVDO system, the traffic data employs adaptive modulation and coding (AMC) that changes the modulation scheme according to the radio state.

  AMC is a function that realizes a high communication speed by providing a high data rate using a high modulation method in an environment with good radio conditions and using a low modulation method so that data can be surely delivered in an environment with bad radio conditions. It is.

  In addition, the signaling message employs a protocol called SLP (Signaling Link Protocol) that guarantees the order of the messages, and a function that transmits a fixed number of times. Specifically, SLP assigns a sequence number to a message to be assigned to each message, and if the number is older than the sequence number expected on the receiving side, it is regarded as an old message and the message is discarded. It has become. SLP guarantees order but does not guarantee for missing messages. These communication protocols are defined in Non-Patent Document 1.

  In addition, there are ARQ (Automatic Repeat reQuest) and HARQ (Hybrid ARQ) as communication methods aiming at high reliability in the wireless connection, and the above signaling message also uses HARQ to transmit the same message for a fixed number of times. Things are going.

  ARQ is an error correction method in which data to be transmitted is divided into smaller blocks for transmission / reception, and when an error occurs during communication on the receiving side, only the block in error is automatically retransmitted. . In addition, HARQ automatically retransmits a block in error as in ARQ, but does not discard the errored block itself, and soft-synthesizes retransmission data to increase the reception success rate at the time of retransmission. It is a way to increase.

  It is also possible to place a plurality of signaling messages on one MAC layer packet (hereinafter referred to as a MAC packet). Putting a plurality of messages in one packet in this way is called bundling the messages.

3GPP2 C.S0024-A Version 3.0 (2.6 Signaling Link Protocol (2-12 to 2-21))

  The reliability of communication in a wireless section, such as between a base station and a terminal, greatly depends on the quality of radio waves in that section. Therefore, even if a message is transmitted a fixed number of times as in the case of a signaling message in the background art, the probability that a message is lost remains relatively high in an environment where the radio quality is poor.

  That said, even if you want to add a new message or change the sequence in order to improve the reliability of communication, the communication protocol between the base station and the terminal is determined by the standard, and easy Cannot be changed. Also, since radio resources are limited, there is a limit to increasing the number of uniform transmissions.

  The present invention provides a radio communication base station system and a radio communication terminal that automatically determine and transmit the number of message transmissions according to changes in radio quality.

  The above-described problem is that a radio communication terminal is accommodated and configured by a radio communication base station and a base station control device, and the radio communication base station includes a radio quality measurement unit that measures radio quality with the radio communication terminal. The base station control device includes a message transmission unit that transmits a message addressed to the wireless communication terminal, and a memory that holds a measurement result of the wireless quality measurement unit. The message transmission unit refers to the memory, and the measurement result This can be solved by a radio communication base station system that transmits the same signaling message a number of times according to.

  Also, connected to the radio base station, the radio quality measurement unit that measures radio quality with the radio base station, the message transmission unit that sends messages addressed to the radio base station, and the measurement results of the radio quality measurement unit The message transmission unit can solve the problem by a wireless communication terminal that refers to the memory and transmits the same signaling message a number of times according to the measurement result.

  By determining the number of times of transmission according to the change in radio quality and transmitting the message a plurality of times, the probability that the message is lost with the minimum necessary communication amount can be lowered.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings using examples. Note that the same reference numerals are assigned to substantially the same parts, and the description will not be repeated.

  First, the configuration of a wireless communication system will be described with reference to FIG. Here, FIG. 1 is a block diagram of the wireless communication system. In FIG. 1, a radio communication system 200 includes a terminal 10, a base station 20 (Base Station) that communicates with the terminal 10, and a BSC 30 (Base Station Controller) that manages and controls the operation of the base station 20. It comprises a PDSN 40 (Packet Data Serving Node, packet data relay device) that relays packets for connection to the Internet 50.

  By operating the terminal 10, the user can connect to the Internet 50 via the base station 20, the BSC 30, and the PDSN 40, and can transmit and receive various data.

  With reference to FIG. 2, the internal structure of a base station and BSC is demonstrated. Here, FIG. 2 is a principal block diagram of the base station and the BSC. In FIG. 2, the base station 20 includes an antenna 21 that transmits and receives radio signals and a radio quality measurement unit 22 that measures radio quality between terminals. The BSC 30 includes a memory 31 that stores data of radio quality measured by the base station 20, a CPU 32 that calculates the number of message transmissions and uses it when transmitting messages, and a message transmission / reception unit 33 that controls transmission of messages to terminals. Is done. The radio quality measurement unit 22 measures the quality of radio signals with the terminal 10. The BSC 30 transmits a message from the message transmission / reception unit 33 via the base station 20 with reference to the memory 31 that holds the measurement result of the wireless quality measurement unit 22. In this specification, the base station 20 and the BSC 30 are collectively referred to as a wireless communication base station system.

  With reference to FIG. 3, an internal configuration of the terminal when a message is transmitted from the terminal will be described. Here, FIG. 3 is a principal block diagram of the terminal. In FIG. 3, a radio terminal 10 includes a radio quality measurement unit 12 that measures radio quality between an antenna 15 that transmits and receives radio signals, a message transmission and reception unit 11 that controls transmission of messages to the terminal, and a base station 20. The CPU 13 is used for calculating the number of message transmissions and transmitting the message, and the memory 14 is used for storing the wireless quality data measured by the wireless quality measuring unit 12. Note that the radio quality measurement method in the radio quality measurement unit 22 of the base station 20 and the radio quality measurement unit 12 of the terminal 10 may be different.

  Next, the packet configuration of the message to be transmitted will be described. The structure of a MAC (Media Access Control) packet will be described with reference to FIG. Here, FIG. 4 shows a format of the MAC packet. In FIG. 4, the MAC packet 70 includes a MAC payload 110 and a MAC header 111. In the MAC payload 110, a Stream Layer packet 105 described in FIG.

  The structure of the Stream Layer packet will be described with reference to FIG. Here, FIG. 5 shows the format of the Stream Layer packet. In FIG. 5, a Stream Layer packet 105 includes a message part 60 for carrying a signaling message, a SNP (Signaling Network Protocol) header 61, an SLP-D (SLP delivery layer) header 62, and an SLP-F which are headers for each protocol. A (SLP fragmentation layer) header 63 and a Stream Layer header 64 are configured.

  A detailed configuration of the SLP-D header will be described with reference to FIG. Here, FIG. 6 shows the format of the SLP-D header. In FIG. 6, the SLP-D header 62 includes elements of a FullHeaderIncluded 84, an AckSequenceValid83, an AckSequenceNumber82, a SequenceValid81, and a SequenceNumber (hereinafter referred to as a sequence number) 80.

  In normal SLP communication, the sequence number 80 in the SLP-D header 62 is incremented each time a message is transmitted. On the receiving side, if the sequence number 80 of the received message is older than the expected number, it is regarded as an old message and the message is discarded. Therefore, even if a change is made so that a plurality of messages having the same sequence number 80 are transmitted, no change is necessary in the processing on the receiving side.

  The embodiment has been described in which the message is transmitted a plurality of times using the sequence number 80 in the SLP-D header 62 of the signaling message (Control Channel message) in the cdma2000 1xEVDO system. However, application is not limited to the cdma2000 1xEVDO system. This can be realized as long as it has a sequence number indicating the order of the messages in the header given to the message and has a function of discarding messages having the same sequence number on the message receiving side.

  With reference to FIG. 7, the flow at the time of message transmission will be described. FIG. 7 is a flowchart of message transmission processing. Here, a case where a message is transmitted from the BSC 30 and the base station 20 side to the terminal 10 will be described. However, a case where a message is transmitted from the terminal 10 to the base station 20 or the BSC 30 may be used.

In FIG. 7, first, the message transmitting / receiving unit 33 adds headers (SNP header 61, SLP-D header 62, SLP-F header 63, and Stream Layer header 64) necessary for transmission to the message 60 (S100). ). Thereafter, the message transmission / reception unit 33 acquires the measured data regarding the wireless quality with the terminal 10 from the memory 31 (S101). Here, the wireless quality data is intended to numerically represent the wireless quality. However, the value may not be a value that directly represents the wireless quality, but may be data that allows the wireless quality to be calculated. An example is RTD (Round Trip Delay, message delay time) or the number of message transmission retries due to a transmission timeout. In addition, data related to wireless quality is stored in the memory 31 from the wireless quality measuring unit 22 periodically or as necessary. Next, the message transmission / reception unit 33 analyzes the quality data and calculates the number of times the message transmission is repeated (S102). The message transmission is repeated for the calculated number of times (S103 to S105). At this time, each message is transmitted in a separate MAC packet 70 and is not transmitted in a bundle.
By taking these steps, it is possible to reduce the probability of missing messages by increasing the number of message transmissions when the radio quality is poor.

  With reference to FIG. 8, the procedure at the time of message transmission will be described. Here, FIG. 8 is a sequence diagram between the BSC and the terminal. Here, the operations of the BSC 30 and the terminal 10 in the case where a message is transmitted from the BSC 30 to the terminal 10 will be described.

  In FIG. 8, first, the BSC 30 adds a header to the message 60 (S111). The BSC 30 acquires data related to wireless quality (S112). The BSC 30 calculates the number of message transmissions (S113).

  Next, the BSC 30 continuously transmits the same message for the number of times calculated in step 112 (S114-1 to S114-3). A response from the terminal 10 is not waited during this continuous transmission. Although the number of transmissions is three here, it is not limited to three.

  Next, the reception operation of the terminal 10 will be described. Here, it is assumed that the first message transmission (S114-1) does not reach the terminal 10, and the second and third message transmissions (S114-2, S114-3) reach the terminal 10. When the terminal 10 receives the second message transmission (S114-2), since this message is the first reception, the reception is successful (S116). Next, when the terminal 10 receives the third message transmission (S114-3), since the message with the same sequence number has already been received, the terminal 10 discards the message transmitted for the third time (S117). . By these processes, even when a message is transmitted a plurality of times, the terminal 10 can correctly receive the message.

  With reference to FIG. 9, the setting of the number of message transmissions based on wireless quality will be described. Here, FIG. 9 is a graph for explaining the temporal change in radio quality and the setting of the number of transmissions associated therewith. In FIG. 9, the vertical axis represents the radio quality, and the higher the value (the smaller the value), the better the radio quality, and the lower the value (the greater the value), the worse the radio quality. . The horizontal axis represents that time passes as it goes to the right. Threshold values (RTD = 100 ms, RTD = 200 ms) are provided as quality evaluation criteria. These two values have the relationship that “the quality of the radio is inferior <RTD = 200 ms <RTD = 100 ms <the quality of the radio is good”.

  At this time, the number of message transmissions is defined as follows. That is, “RTD> 200 ms” is three times, “100 ms <RTD ≦ 200 ms” is two times, and “RTD ≦ 100 ms” is one time.

  As shown in the curve of FIG. 9, when the wireless quality is changed, the message is transmitted once from t0 to t1, and the wireless quality is deteriorated in the section from t1 to t2, and the message is transmitted twice. From t2 to t3, the radio quality is further deteriorated, and is three times. Thereafter, the radio quality is improved and the period from t3 to t4 is reduced to twice, and after t4, the quality is deteriorated again, so that the time is set to three. Establish a threshold for evaluating radio quality, and calculate the optimum number of message transmissions according to radio quality by changing the number of message transmissions when the actual radio quality data value exceeds the threshold. I can do it. Although two threshold values are provided here, the threshold value is not limited to two.

In this way, by changing the number of message transmissions according to the radio quality, the number of transmissions is increased when the radio quality is poor, and the number of transmissions is decreased when the radio quality is good. In the above-described embodiment, only the number of message transmissions is optimized according to the radio quality. However, optimization of a bundle of a plurality of messages may also be performed. When the radio quality is good, the efficiency of radio resources can be realized by transmitting a plurality of messages in one packet.

  With reference to FIG. 10, the structure of the MAC packet when a plurality of messages are bundled will be described. Here, FIG. 10 shows another format of the MAC payload. In FIG. 10, when the MAC payload 110A is bundled, a plurality of the stream layer packets 105 described in FIG. 4 are placed.

  With reference to FIG. 11, the transmission process of a terminal when a bundle is also included is demonstrated. Here, FIG. 11 is a flowchart of the transmission processing of the message transmission / reception unit 11. The flowchart for transmitting a message from the BSC 30 to the terminal 10 is the same.

  After the message transmission process is started, first, the message transmitting / receiving unit 11 adds a header (SNP header 61, SLP-D header 62, SLP-F header 63, and Stream Layer header 64) necessary for transmission to the message 60 ( S121). Thereafter, the message transmission / reception unit 11 acquires data on the wireless quality with the measured base station 20 from the memory 14 (S122). Here, the wireless quality data is intended to be a numerical representation of the wireless quality such as the total carrier power to noise power ratio (C / I). However, the value may not be a value that directly represents the wireless quality, but may be data that allows the wireless quality to be calculated. In addition, data related to wireless quality is stored in the memory 14 from the wireless quality measuring unit 12 periodically or as necessary.

  Thereafter, the message transmission / reception unit 11 checks the wireless quality and divides the process according to the result (S123). In step 123, when the wireless quality is poor (NO), the message transmitting / receiving unit 11 executes a process of transmitting the message a plurality of times. In step 123, if the wireless quality is good (YES), the message transmission / reception unit 11 executes a bundling process.

  In the case of processing for transmitting a message a plurality of times, the message transmitting / receiving unit 11 analyzes the quality data and calculates the number of times the message transmission is repeated (S124). The message transmission / reception unit 11 repeats transmission of the message for the calculated number of times (S126 to S128). At this time, the message transmitting / receiving unit 11 transmits each message in a separate MAC packet, and does not transmit it in a bundle.

  In the case of bundling processing, the message transmission / reception unit 11 first checks whether there is enough free space to store a message (StreamLayer packet 105) to be transmitted to a buffer (message transmission buffer) in the message transmission / reception unit 11. (S129). This is because, when there is a message (StreamLayer packet 105) that is still stored in the buffer in an attempt to send it in a bundle, even if a new message (StreamLayer packet 105) to be sent is added, This is to check whether the maximum size of the MAC payload 110 is exceeded.

  If there is an area that can be stored in step 129 (YES), the message transmitting / receiving unit 11 stores the message in the buffer as it is (S131). Next, the message transmission / reception unit 11 checks whether there is still a message waiting for transmission (S132). If there is a message waiting for transmission (YES), there is a possibility that it can be bundled, so the process proceeds to step 121 while the message is stored in the buffer. If there is no message waiting for transmission in step 132 (NO), the message currently stored in the buffer is transmitted (S133), and the process ends.

  In step 129, when the maximum size of the MAC payload 110 is exceeded (cannot be stored in the buffer) (NO), the message transmission / reception unit 11 transmits the message currently stored in the buffer (S130). Thereafter, the message that could not be stored is stored in the buffer (S131).

  By following these procedures, if the radio quality is poor, the number of message transmissions is increased, and if the radio quality is good, bundling messages reduces the probability of message loss, and radio resources Can be used efficiently.

  With reference to FIG. 12, the number of message transmissions and the change in bundle due to the change in radio quality will be described. Here, FIG. 12 is a graph for explaining the temporal change of radio quality, the number of transmissions associated therewith, and the setting of bundles.

  In FIG. 12, the vertical axis represents wireless quality, and the higher the value (the smaller the value), the better the wireless quality, and the lower the value (the larger the value), the worse the wireless quality. The horizontal axis represents that time passes as it goes to the right. Threshold values (RTD = 100 ms, RTD = 200 ms, RTD = 300 ms) are provided as quality evaluation criteria. These three values have a relationship that “radio quality is poor <RTD = 300 ms <RTD = 200 ms <RTD = 100 ms <good radio quality”.

  At this time, the number of message transmissions is defined as follows. That is, “RTD> 300 ms” is transmitted four times, “200 ms <RTD ≦ 300 ms” is transmitted three times, “100 ms <RTD ≦ 200 ms” is transmitted twice, and “RTD ≦ 100 ms” is transmitted once. For message bundles, when RTD = 100 ms is used as a threshold and radio quality is higher than RTD = 100 ms (RTD ≦ 100 ms), processing is performed so as to actively bundle, and the radio quality is RTD = 100 ms. If it is lower (RTD> 100 ms), message bundling is not performed. As described above, the number of message transmissions and whether or not the bundle can be executed can be set independently. When bundling messages, since the radio quality is good, basically, the number of message transmissions is preferably set to 1, but may be larger than 1.

  As shown in the curve of FIG. 12, when the wireless quality changes, bundles are performed from t0 to t1 and a message is transmitted once. In the interval from t1 to t2, since the quality of the radio has deteriorated, the number of times is increased without performing bundling, and transmission is performed twice. From t2 to t3, since the wireless quality is further deteriorated, the number of transmissions is increased and transmission is performed three times without performing bundling. During the period from t3 to t4, the number of transmissions is further set to 4 without performing bundling. The quality has improved after t4, but since 200 ms <RTD ≦ 300 ms, bundling is not performed, and the number of transmissions is reduced to 3 times. To do. Establish a threshold for evaluating radio quality, and calculate the optimal number of message transmissions according to radio quality by changing the number of message transmissions when the actual radio quality data value exceeds the threshold. I can do it. Further, by determining whether or not to execute the bundle based on the threshold value, it is possible to effectively use the radio resource according to the radio quality. In this embodiment, three threshold values are provided. However, the threshold value is not limited to three values.

  In this way, by changing the number of message transmissions and bundle availability according to the radio quality, the number of transmissions is increased when the radio quality is poor, and the number of transmissions is reduced and radio resources are used effectively when the radio quality is good. can do. Therefore, the probability of missing messages can be effectively reduced.

1 is a block diagram of a wireless communication system. It is a principal part block diagram of a base station and BSC. It is a principal part block diagram of a terminal. It is a format of a MAC packet. This is the format of the Stream Layer packet. This is the format of the SLP-D header. It is a flowchart of the transmission process of a message. It is a sequence diagram between BSC and a terminal. It is a graph explaining the time change of radio | wireless quality, and the setting of the frequency | count of transmission accompanying it. Other MAC payload formats. 4 is a flowchart of a transmission process of the message transmission / reception unit 11. It is a graph explaining the time change of radio | wireless quality, the frequency | count of transmission accompanying it, and the setting of a bundle.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Terminal, 11 ... Message transmission / reception part, 12 ... Radio quality measurement part (terminal side), 13 ... CPU, 14 ... Memory, 15 ... Antenna 20 ... Base station, 21 ... Antenna, 22 ... Radio quality measurement part (base station) Side) 30 ... BSC, 31 ... memory, 32 ... CPU, 33 ... message transmission / reception unit (BSC side), 40 ... PDSN, 50 ... Internet, 60 ... message, 70 ... MAC packet, 102 ... SLP-D header, 105 ... StreamLayer packet, 110 ... MAC payload, 111 ... MAC header, 200 ... wireless communication system.

Claims (4)

In a radio communication base station system that accommodates radio communication terminals,
It consists of a radio communication base station and a base station controller,
The radio communication base station includes a radio quality measurement unit that measures radio quality with the radio communication terminal,
The base station control device includes a message transmission unit that transmits a message addressed to the wireless communication terminal, and a memory that holds a measurement result of the wireless quality measurement unit,
The radio communication base station system, wherein the message transmission unit transmits the same signaling message a number of times according to the measurement result with reference to the memory. The wireless communication base station system according to claim 1,
The said message transmission part provides the same sequence number, when transmitting the said signaling message in multiple times, The radio | wireless communication base station system characterized by the above-mentioned. In a wireless communication terminal connected to a wireless base station,
A radio quality measurement unit that measures radio quality with the radio base station, a message transmission unit that transmits a message addressed to the radio base station, and a memory that holds a measurement result of the radio quality measurement unit,
The wireless communication terminal, wherein the message transmission unit refers to the memory and transmits the same signaling message a number of times according to the measurement result. The wireless communication terminal according to claim 3,
The said message transmission part provides the same sequence number, when transmitting the said signaling message in multiple times, The radio | wireless communication terminal characterized by the above-mentioned.

Images