WO2008026664A1

WO2008026664A1 - Communication system, communication device and communication method

Info

Publication number: WO2008026664A1
Application number: PCT/JP2007/066815
Authority: WO
Inventors: Jun Kano
Original assignee: Kyocera Corporation
Priority date: 2006-08-30
Filing date: 2007-08-29
Publication date: 2008-03-06
Also published as: JP2008060850A; JP4486948B2

Abstract

In an interpretation period INTALL used in a communication system, a future orienting period INTF corresponding to a 5-bit sequence number (LastSendAckNum) transmitted even after LastSendAckNum±0, and a past orienting period INTP corresponding to the 5-bit sequence number (LastSendAckNum) transmitted before LastSendAckNum±0 are provided. A transmitting side codes 13-bit sequence number into a 5-bit sequence number as the upper limit until the 5-bit sequence number corresponding to the future oriented period INTF.

Description

Specification

COMMUNICATION SYSTEM, COMMUNICATION DEVICE, AND COMMUNICATION METHOD

Technical field

[0001] The present invention transmits only a partial number bit string that is a part of a number bit string to be transmitted, such as LSB encoding, and has an interpretation period that is a range of the partial number bit string that can be decoded into the number bit string. The present invention relates to a communication system, a communication apparatus, and a communication method in which a sliding window method for sliding sequentially is introduced.

Background art

[0002] In a wireless communication system such as a mobile communication system, compared to a wired communication system, transmitted packets are often lost in a wireless section. Therefore, automatic retransmission is generally performed to retransmit lost packets. Control (eg, ARQ) is widely used! (Eg, Patent Document 1 and Non-Patent Document 1).

[0003] In addition, in a wireless communication system, various encoding methods for reducing (compressing) the number of bits of information to be transmitted have been realized in order to efficiently use wireless resources such as frequency bands. For example, only the information of the specified number of bits (partial number bit string) from the least significant bit (LSB) in the number bit string (V-target) to be transmitted by the transmitter, such as the sequence number used in the packet header, is transmitted. LSB encoding is known.

[0004] In LSB encoding, only information on the specified number of bits from the LSB is transmitted. Therefore, the receiving apparatus supplements information on the upper bits that were not transmitted to the received information on the number of specified bits from the LSB. , It is necessary to decode it into a number bit string (V—target).

[0005] Specifically, the transmission device and the reception device share a reference value (V—ref). The transmitting apparatus transmits a sequence number (SN) that is a part of a number bit string to be transmitted. When the number of bits of the sequence number (SN) is k bits, receiving devices that share the reference value (V—ref) receive V—ref to V— by receiving the sequence number (SN). The value up to the range of ref + Z ¹ ^ ¹ can be interpreted as a V-target, that is, a number bit string that should be transmitted by the transmitter. Here, V—ref to V—ref + 2 ^{k 1} are called “interpretation inte rval”. [0006] When LSB encoding is used, a sliding window method is widely used in order to make the above-described interpretation period variable. In the sliding window method, the variable (P) is introduced and the reference value (V—ref) is slid sequentially. Specifically, if the number bit string (V—target) can be decoded based on the sequence number (SN) received by the receiving device, the value of the reference value (V—ref) is sent between the transmitting device and the receiving device. Is updated.

Patent Document 1: Japanese Unexamined Patent Publication No. 2002-9741 (Pages 5-6, Fig. 1)

Non-Patent Document 1: "High Capacity-Spatial Division Multiple Access (HC-SDMA) WTSC-2005-032 (ATIS / ANSI)"

Disclosure of the invention

[0007] By the way, in general, a wireless communication system often has an extremely small packet size compared to a wired communication system. In other words, in order to improve the transmission efficiency in packet units, it is desirable to reduce the number of bits allocated to the packet header as much as possible.

[0008] However, when a sequence number (SN) encoded according to LSB encoding is transmitted by a packet header, the number of bits that can be expressed as a sequence number (SN) is reduced if the number of bits allocated to the header is reduced. Will be limited. Further, in the LSB encoding in which the sliding window method described above is introduced, the reference value (V-ref) slides sequentially during communication, so that the receiving device converts the number bit string (V-target) based on the sequence number (SN). The interpretation period that can be correctly decoded is also slid sequentially.

[0009] For this reason, in LSB encoding that introduced the sliding window method, the sequence number

When the number of bits that can be expressed as (SN) is limited, if a packet that falls outside the current interpretation period “outside” is retransmitted by ARQ, the receiving device uses the retransmitted packet to generate a number bit string ( V—target) cannot be correctly decoded, and the reference value (V—ref) is not synchronized between the transmitting device and the receiving device.

[0010] On the other hand, in order to avoid the occurrence of this problem, providing information indicating that it is a retransmitted packet in the header causes another problem that the number of bits to be allocated to the header increases. .

[0011] Therefore, the present invention has been made in view of such a situation, and automatic replay such as ARQ. When transmission control is used, a communication system or communication that uses a coding method that transmits only a part of the number bit string to be originally transmitted, such as LSB encoding, and more reliably decodes the number bit string on the receiving side. Providing a device and a communication method will be an urgent matter.

In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is that the transmitter (radio terminal 100) encodes and transmits the partial number bit string (5-bit sequence number), which is a part of the number bit string (13-bit sequence number) to be transmitted. ) And the received partial number bit string and a reference value (LastSendAckNum, LastAckPeer) shared by the transmitting device and the receiving device, the partial number that can be decoded into the number bit string. A receiving apparatus (radio base station 20) that decodes the number bit string while changing the period (interpretation period INT) that is the range of the bit string

ALL

0), and is a communication system (communication system 10) in which automatic retransmission control (for example, ARQ) of the partial number bit string is executed, wherein the transmitting device has received the receiving device normally. With respect to the future direction period (future direction period INT) associated with the partial number bit string transmitted after the latest partial number bit string with reference to the latest partial number bit string (LastSendAckNum ± 0) as the partial number bit string, Encoding

F

An encoding processing unit that performs the past, the reception device is associated with a part number bit string transmitted from the transmission device at least before the latest part number bit string with reference to the latest part number bit string For direction period (past direction period INT)

P

The main point is to have a decoding processing unit (encoding 'decoding processing unit 105) that performs coding and decoding.

[0013] According to such a communication system, in a period that is a range of the partial number bit string that can be decoded into the number bit string, it is associated with the partial number bit string that is transmitted after the latest partial number bit string. A future direction period and a past direction period associated with the partial number bit string transmitted before the latest partial number bit string are provided. In addition, the transmitting apparatus encodes the number bit string into a partial number bit string up to the partial number bit string associated with the future direction period.

For this reason, a partial number bit string that deviates from the range of the period in the receiving apparatus is transmitted. It is not retransmitted by the side. In other words, even when a packet storing the partial number bit 歹 IJ is retransmitted by automatic retransmission control, a past direction period associated with the partial number bit string transmitted before the latest partial number bit string is provided! Therefore, the partial number bit string can be correctly decoded into the number bit string.

[0015] A second feature of the present invention relates to the first feature of the present invention, and is summarized in that the past direction period is longer than the future direction period.

[0016] A third feature of the present invention relates to the first feature of the present invention, wherein a period that is a range of a partial number bit string that can be decoded into the number bit string by the receiving device is A future direction period and the past direction period, and the future direction period occupies approximately half of the period that is the range of the partial number bit string that can be decoded into the number bit string by the receiving device; The gist of the encoding processing unit is to encode the number bit string into a partial number bit string up to a partial number bit string associated with the future direction period.

[0017] A fourth feature of the present invention relates to the first feature of the present invention, wherein when the encoding processing unit retransmits the partial number bit string, the partial number associated with the future direction period. It is necessary to encode the number bit string into a partial number bit string up to the bit string.

[0018] A fifth feature of the present invention relates to the first to fourth features of the present invention, wherein the partial number bit 歹 IJ is stored in a packet (for example, packet Py), and the partial number bit string is: The gist is to be associated with the packet.

A sixth feature of the present invention relates to the first to fourth features of the present invention, wherein the partial number bit 歹 IJ is stored in a packet, and the partial number bit string is stored in the packet. The gist is that it is associated with a data string (data 歹 IJDB).

[0020] A seventh feature of the present invention is that a partial number bit string which is a part of a number bit string to be transmitted is received from a communication destination, and the received partial number bit string and the received communication destination are shared by V Communication that uses reference values to decode the number bit sequence while sequentially changing the period that is the range of the partial number bit sequence that can be decoded into the number bit sequence, and to perform automatic retransmission control of the partial number bit sequence Device, wherein said period is normally A future direction period associated with a partial number bit string transmitted from the communication destination after the latest partial number bit string based on the latest partial number bit string that is the received partial number bit string, and the latest part A past direction period associated with the partial number bit string transmitted before the number bit string, and the past direction period has a length equal to or longer than the future direction period, and the latest partial number bit string And a decoding processing unit that performs the decoding for at least the past direction period from the latest partial number bit string.

[0021] An eighth feature of the present invention is that the partial number bit string is received from the communication device on the transmission side that encodes and transmits the partial number bit string that is a part of the number bit string to be transmitted, and the received partial part A number bit string and a period that is a range of a partial number bit string that can be decoded into the number bit string by using a reference value! / Shared by the communication device on the transmission side! / A communication device that decodes the number bit string while sequentially changing and executes automatic retransmission control of the partial number bit sequence, the latest partial number being the partial number bit sequence that the receiving side communication device has successfully received With a bit string as a reference, an encoding processing unit is provided that performs the encoding for the future direction period associated with the partial number bit string transmitted after the latest partial number bit string. It is the gist of.

[0022] A ninth feature of the present invention relates to the eighth feature of the present invention. In the future direction period, a range of a partial number bit string that can be decoded into the number bit string by the receiving-side communication device. The encoding processing unit encodes the number bit string into a partial number bit string up to a partial number bit string associated with the future direction period. The gist is to do.

[0023] A tenth feature of the present invention relates to the eighth feature of the present invention, wherein when the encoding processing unit retransmits the partial number bit string, the partial number associated with the future direction period. It is necessary to encode the number bit string into a partial number bit string up to the bit string.

[0024] An eleventh feature of the present invention relates to the seventh to tenth features of the present invention, wherein the partial number bit 歹 IJ is stored in a packet, and the partial number bit string corresponds to the packet. The gist is that it is attached. A twelfth feature of the present invention relates to the seventh to tenth features of the present invention, wherein the partial number bit 歹 IJ is stored in a packet, and the partial number bit string is stored in the packet. The gist is that it is associated with the data string to be processed.

[0026] A thirteenth feature of the present invention is that a transmitting device encodes and transmits a partial number bit string, which is a part of a number bit string to be transmitted, and a receiving device receives the partial number bit string received, and Using the reference value shared by the transmitting apparatus and the receiving apparatus, the step of decoding into the number bit string while sequentially changing the period that is the range of the partial number bit string that can be decoded into the number bit string A communication method in which automatic retransmission control of the partial number bit string is executed between the transmission device and the reception device, wherein the transmission device is configured to receive the unit successfully received by the reception device. Based on the latest part number bit string which is a minute number bit string, the latest part number bit 未来 Future direction associated with the part number bit string transmitted later For the period, the step of performing the encoding (tl), and the receiving device based on the latest partial number bit string at least in the partial number bit string transmitted from the transmitting device prior to the latest partial number bit string. The gist of the present invention is to further comprise steps (t2 to t3) for performing the decoding for the associated past direction period.

[0027] According to the feature of the present invention, when automatic retransmission control such as ARQ is used, an encoding method that transmits only a part of a number bit string to be originally transmitted, such as LSB encoding, is used. Can provide a communication system, a communication device, and a communication method for more reliably decoding the number bit string.

Brief Description of Drawings

FIG. 1 is an overall schematic configuration diagram of a communication system according to an embodiment of the present invention.

FIG. 2 is a functional block configuration diagram of a communication device (wireless terminal) according to an embodiment of the present invention.

FIG. 3 is a functional block configuration diagram of a communication apparatus (radio base station) according to the embodiment of the present invention.

FIG. 4 is a configuration diagram of packets transmitted and received by the communication device according to the embodiment of the present invention. [Fig. 5] Fig. 5 is an explanatory diagram for explaining how to use the RAM provided in the communication device according to the embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of an interpretation period according to the embodiment of the present invention.

FIG. 7 is a communication sequence diagram executed between communication apparatuses according to the embodiment of the present invention.

FIG. 8 is a communication sequence diagram executed between communication apparatuses according to a conventional example.

FIG. 9 is a diagram showing a relationship between a 13-bit sequence number and a 5-bit sequence number. FIG. 10 is a diagram showing an example of a retransmission packet according to the embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones.

Accordingly, specific dimensions and the like should be determined in consideration of the following description. In addition, it goes without saying that the drawings include parts having different dimensional relationships and ratios.

[0031] (Overall schematic configuration of communication system)

FIG. 1 is an overall schematic configuration diagram of a communication system according to the present embodiment. As shown in FIG. 1, the communication system 10 includes a radio terminal 100 and a radio base station 200. Note that the quantities of the radio terminal 100 and the radio base station 200 included in the communication system 10 are not limited to the quantities shown in FIG.

[0032] The communication system 10 uses LSB encoding that transmits only the information (partial number bit string) of the specified number of bits from the least significant bit (LSB) in the number bit string to be transmitted. Specifically, of the 13-bit sequence number added to the packet, only the 5-bit information from the least significant bit (LSB), that is, the 5-bit sequence number is stored in the packet header and transmitted ( (See Figure 9). [0033] Furthermore, in the communication system 10, a 5-bit sequence number stored in the header of the received packet and a reference value (LastSendAckNum, LastAckPeer) shared by the radio terminal 100 and the radio base station 200 are used. A sliding window method has been introduced in which a period within a range of 5-bit sequence numbers that can be decoded into 13-bit sequence numbers, specifically, an interpretation interval is sequentially slid. .

Further, in the communication system 10, automatic packet retransmission control (ARQ) is executed.

(Function block configuration of communication system)

FIG. 2 is a functional block configuration diagram of the wireless terminal 100. FIG. 3 is a functional block configuration diagram of the radio base station 200. As shown in FIGS. 2 and 3, the wireless terminal 100 and the wireless base station 20

0 has almost the same functional block configuration.

Specifically, the wireless terminal 100 includes a wireless communication unit 101, a retransmission control unit 103, an encoding / decoding processing unit 105, a sliding window control unit 107, and a packet processing unit 109 (including a RAM 109a).

Radio base station 200 includes radio communication section 201, retransmission control section 203, encoding / decoding processing section 205, sliding window control section 207, and packet processing section 209 (including RAM 209a).

[0038] Hereinafter, each functional block of radio terminal 100 will be described, and description of each functional block of radio base station 200 will be omitted. In the following, portions related to the present invention will be mainly described. Therefore, the radio terminal 100 and the radio base station 200 may be provided with a block (a power supply unit or the like) that is not shown in the figure or omitted in the description, which is essential for realizing the function as the device. Please keep in mind. In the present embodiment, the uplink communication from the radio terminal 100 to the radio base station 200 is described as an example, but the downlink communication from the radio base station 200 to the radio terminal 100 is executed in the same manner.

Radio communication unit 101 transmits and receives radio signals to and from radio base station 200. The wireless communication unit 101 is connected to the encoding / decoding processing unit 105, and executes modulation / demodulation processing between the baseband signal including the packet and the wireless signal.

[0040] Retransmission control section 103 executes automatic packet retransmission control (ARQ). With this ARQ, the sending side sends the sequence number added to the last packet to be sent or data (IJ). The number is stored in the header of the packet, and the packet is transmitted. The receiving side returns, as ack, the sequence number of the packet that stores the last data string that is continuous without being lost among the data strings stored in the received packet.

[0041] When the transmitting side receives an ack that is older than the sequence number of a packet that has already been transmitted! /, A sequence number, that is, a sequence number having a smaller numerical value, the data string corresponding to the sequence number received as ack Resend the packet containing When the receiving side acquires the missing part of the data string by the retransmitted packet, it returns the sequence number of the packet storing the last data string as ack to the transmitting side.

The encoding / decoding processing unit 105 executes processing related to LSB encoding. Specifically, the encoding / decoding processing unit 105 includes only information of 5 bits from the least significant bit (LSB) in the 13-bit sequence number added to the packet assembled by the packet processing unit 109, That is, the 5-bit sequence number is stored in the packet header.

In addition, the encoding / decoding processing unit 105 decodes the 5-bit sequence number stored in the header of the received packet into a 13-bit sequence number.

[0044] The sliding window control unit 107 performs control of the sliding window. Specifically, the sliding window control unit 107 uses the 5-bit sequence number stored in the header of the received packet and the reference value shared by the radio terminal 100 and the radio base station 200, and The interpretation period that is the range of the 5-bit sequence number that can be decoded into the bit sequence number is sequentially changed. Specifically, the sliding window control unit 107 sequentially slides the interpretation period.

Note that the reference value shared between the radio terminal 100 and the radio base station 200 is a value that is updated in cooperation between the radio terminal 100 and the radio base station 200. In the state, LastSendAckNum and LastAckPeer (see Fig. 5 (a) and (b)) are used as reference values.

The packet processing unit 109 executes packet assembly and disassembly processing. Specifically, the packet processing unit 109 executes packet assembly and disassembly processing while storing a data string stored in the packet in the RAM 109a.

[0047] (Packet configuration) Next, the configuration of packets transmitted and received by the wireless terminal 100 and the wireless base station 200 will be described. 4A and 4B are configuration diagrams of buckets transmitted and received by the radio terminal 100 and the radio base station 200. FIG.

[0048] In the present embodiment, the lengths of the packets Px and Py are fixed (76 bits). Packets Px and Py are composed of a header HD and a payload PL. The header HD of packets Px and Py is defined as shown in Table 1.

[0049] [Table 1]

Content of Bid Name Length

Bi-number Toshike 013

Bi No. Tosike 15

After being included in the data, the end of the continuous data reception has been completed without any omissions.

Pat number Ketoshike

The turn number or ikeshake noson 31 5 /

Uib9nS Ketoshike hits all the case numbers

F 0 hdt eeerorm: aa--5h 1 under the ketoshike where the bi-storing ranks in the same position hdt ee ererorma:--

CO

+-»

(0

E

ϋ

α> (0

(0

0)

In the present embodiment, as shown in FIG. 4 (a), the packet Px in which the 13-bit sequence number is stored in the header HD, or as shown in FIG. 4 (b), the least significant of the 13-bit sequence numbers. Only the 5-bit information from the bit (LSB), that is, the 5-bit sequence ¾ is the header H The packet Py stored in D is properly used.

[0050] In the present embodiment, the sequence numbers (13-bit sequence numbers, 5-bit sequence numbers) are associated with packets (packets Px, Py).

[0051] In packet Px, the length of header HD is 27 bits. On the other hand, in packet Py, the length of header HD is 19 bits. In other words, in packet Py, the length of the header HD is shortened by 8 bits.

[0052] The payload PL is composed of padding bits PB and a data string DB. The padding bit PB is a bit for indicating the start position of the data string DB, and is the portion up to the first “1” in the payload PL. In other words, the length of padding bit PB is variable.

[0053] The data string DB is located immediately after the padding bit PB. In the data string DB, the bit immediately after the padding bit PB is the MSB of the first data byte (data byte 1), and the last bit of the packets Px and Py is the last data byte (for example, data LSB of byte 6).

[0054] As shown in Fig. 4 (a), a packet Px in which a 13-bit sequence number is used can store a maximum of 6 bytes of data. On the other hand, as shown in Fig. 4 (b), a packet Py using a 5-bit sequence number can store a maximum of 7 bytes of data. The packets Px and Py can be configured with the payload PL only by the padding bits PB, that is, the payload PL is not included in the data string DB! /. In this embodiment, a packet in which the payload PL is composed only of the padding bits PB is referred to as an “empty data bucket” (refer to the lowest stage in FIGS. 4A and 4B).

[0055] (Usage of RAM)

Next, usage forms of the RAM 109a configuring the packet processing unit 109 of the radio terminal 100 and the RAM 209a configuring the packet processing unit 209 of the radio base station 200 will be described.

FIGS. 5 (a) and 5 (b) are explanatory diagrams for explaining usage patterns of the RAM 109a and the RAM 209a. Here, a case where radio terminal 100 transmits packet Py to radio base station 200 will be described.

[0057] When the wireless terminal 100 and the wireless base station 200 establish a logical communication path, The line terminal 100) and the receiving side (radio base station 200) set the initial value of the sequence number (13-bit sequence number, 5-bit sequence number) to "0".

[0058] The transmission side manages the following variables.

[0059]. LastSendNum: Sequence number of the last packet already transmitted

• LastAckPeer: Sequence number received as ack

The transmission side stores the payload PL (data string DB) stored in the packet with the LastSendNum added from the packet with the sequence number next to the LastAckPeer added in the RAM 109a as the ack wait transmission data TD. Prepare for packet retransmission.

[0060] Since the sequence number is 13 bits, 0 to 8191 can be expressed. When the sequence number reaches 8191, it returns to 0, and values from 0 to 8191 are used repeatedly. The “last” packet or data (IJ) is the most recently transmitted or received packet or data (IJ).

[0061] The transmission side determines the difference between the sequence number of the packet to be transmitted and the LastAckPeer.

1S 2 ⁽⁵ 1, ie if it is within 15, use a 5-bit sequence number instead of a 13-bit sequence number.

On the other hand, the receiving side manages the following variables.

[0063]. LastSendAckNum: Sequence number of the packet that stores the last data string that is not missing and is continuous among the data strings stored in the received packet

LastReceiveNum: Sequence number of the packet that stores the last data string received

In FIG. 5 (b), the received data RD1 indicates the payload PL (data string DB) that has already been received. Unreceived data RD2 indicates a payload PL (data 歹 IJDB) that has not been received yet.

[0064] (Interpretation period)

Next, the interpretation period managed by the radio terminal 100 and the radio base station 200 will be described. FIG. 6 shows the structure of the interpretation period according to this embodiment. As described above, in the present embodiment, since the 5-bit sequence number is used by LSB encoding, the size of the interpretation period INT is 32 (= 2 ⁵ ). [0065] The interpretation period INT is provided with a future direction period INT and a past direction period INT.

ALL F P

. Future direction period INT is a 5-bit sequence number that radio base station 200 has successfully received.

F

LastSendAckNum ± 0 (latest part number bit 歹 lJ)

5-bit sequence number sent after AckNum ± 0 (LastSendAckNum ± 0

~: Corresponding to LastSendAckNum + 15).

[0066] The past direction period INT is at least Las p with respect to LastSendAckNum ± 0.

Corresponds to a 5-bit sequence number (LastSendAckNum—16 to LastSendAckNum—1) transmitted before tSendAckNum ± 0. In other words, the future period I NT occupies approximately half of the interpretation period INT.

F ALL

[0067] In the present embodiment, the encoding / decoding processing unit 105 (encoding * decoding processing unit 205) uses 13 bits as an upper limit up to the 5-bit sequence number associated with the future direction period INT.

F

Encode the sequence number into a 5-bit sequence number. That is, the encoding 'decoding unit 105 (encoding' decoding unit 205), to the LastAckPeer, 15 (= 2 does not execute the LSB encoding beyond ⁽⁵ _ ^upsilon 1). Thus, the reception The side (for example, the radio base station 200) does not receive a 5-bit sequence number that is 15 or more apart from the LastSendAckNum, that is, the receiving side receives data using the future direction period INT.

F

The 5-bit sequence number can always be decoded into a 13-bit sequence number.

[0068] More specifically, even when ack (LastSendAckNum) is not normally returned to the transmitting side (for example, wireless terminal 100), the 5-bit sequence number of the packet to be retransmitted by the transmitting side is more than LastSendAckNum-16. It is guaranteed to be close to the current value. In other words, a 5-bit sequence number that deviates from the range of the interpretation period INT on the receiving side.

ALL

Are not retransmitted by the sender.

[0069] (Operation of communication system)

Next, the operation of the communication system 10 will be described. Specifically, an operation will be described in which wireless terminal 100 sequentially transmits packet Py (see FIG. 4B) storing a 5-bit sequence number to wireless base station 200.

[0070] (1) Operation according to this embodiment

FIG. 7 is a communication sequence diagram executed between the radio terminal 100 and the radio base station 200. is there. Assume that the wireless terminal 100 and the wireless base station 200 have already established a logical communication path prior to the execution of the communication sequence shown in FIG. The transmitting side (wireless terminal 100) initializes the values of LastSendNum and LastAckPeer to 0. In addition, the receiving side (radio base station 200) initializes the values of LastSendAckNum and LastReceiveNum to 0.

Radio terminal 100 transmits packet P1 storing a 5-bit sequence number to radio base station 200 (timing tl). “00001” (see SN = 00001 in the figure, the same applies hereinafter) indicating the lower 5 bits of the 13-bit sequence number (00000000 00001) is added to the packet PI as the 5-bit sequence number. Note that 00001 is not included in the interpretation period INT.

ALL

Located in next period INT.

F

[0072] Further, when transmitting the packet P1, the wireless terminal 100 updates the value of LastSendNum. More specifically, the unspring terminal 100 updates: “LastSendNum” is updated to 00000, 00001.

[0073] Radio base station 200 receives packet P1 (timing t2). The radio base station 200 decrypts the packet P1 and obtains the data IJDB included in the packet P1. When receiving the packet P1, the radio base station 200 sets the interpretation period INT in the radio base station 200 to 1.

ALL

Slide one. In this case, radio base station 200 updates the value of LastReceiveNum to 00001 for 00000 force.

[0074] If the packet P1 is successfully decoded, the radio base station 200 returns ackl indicating that the packet P1 has been received normally to the radio terminal 100 (timing t3). When the radio base station 200 transmits ackl, the value of LastSendAckNum is updated. Specifically, the wireless terminal 100 (or LastSendAckNum) is updated to 00000, 00001.

[0075] When receiving the ackl from the radio base station 200, the radio terminal 100 updates the value of LastAckPeer (timing t4). Specifically, the wireless terminal 100 updates the value of LastAckPeer from 00 000 to 00001. In this case, the future period INT in the wireless terminal 100 is slid by one.

F

Thereafter, similarly to packet P 1, packets P 2 to P 5 are transmitted from radio terminal 100 to radio base station 200. Here, it is assumed that ack4 is lost in the radio section. Specifically, the following cases are assumed. First, the radio base station 200 receives the packet P4 (timing t5). Then, the radio base station 200 updates the value of LastReceiveNum. That is, the radio base station 200 updates the value of LastReceiveNum from 00011 to 00100.

[0078] Since radio base station 200 was able to receive packet P4, the power to send back ack4 indicating that packet P4 was normally received to radio terminal 100 Radio terminal 100 was not able to receive ack4 .

[0079] Next! /, Radio base station 200 receives packet P5 (timing t6). When receiving the packet P5, the radio base station 200 0 suspends the interpretation period INT of the radio base station 200 by one.

ALL

Id. As a result, the value of LastReceiveNum is updated to 00100 force, et al.

[0080] Also, when the base transceiver station 200 transmits ack5, as with LastReceiveNum,

Update the value of SendAckNum.

[0081] On the other hand, since the wireless terminal 100 has not received ack4, even if ack5 is received, LastAck

Do not slide Peer value. That is, the value 00011 updated when ack3 is received is held as the value of LastAckPeer.

Next, since the wireless terminal 100 has not received ack4 from the wireless base station 200, the wireless terminal 100 retransmits the packet P4 to the wireless base station 200 (timing t7). Since the value of LastAckPeer is updated as 00011 when ack3 is received, wireless terminal 100 uses the 13-bit sequence number (00000000 00100) of packet P4 to be retransmitted as the 5-bit sequence number (00100). ) Can be encoded.

Radio base station 200 receives retransmitted packet P4 (timing t8). Wireless base station

200 is the power that has already updated the value of LastReceiveNum to 00101 at the time of receiving packet P5 (timing t6). In this embodiment, the interpretation period INT is the past direction.

ALL

Since it is also provided in the period INT, the radio base station 200 is added to the packet P4.

p

The 5-bit sequence number (00100) can be decoded without error to the 13-bit sequence number (00000000 00100).

[0084] (2) Operation according to conventional example

Next, with reference to FIG. 8 and FIG. In the communication system, the operation of the wireless terminal sequentially transmitting the packet Py (see FIG. 4 (b)) storing the 5-bit sequence number to the wireless base station will be described.

FIG. 8 is a communication sequence diagram executed between the radio terminal and the radio base station according to the conventional example. In this communication sequence, as in the communication sequence between the radio terminal 100 and the radio base station 200 according to the present embodiment shown in FIG. 7, packets P1 to P5 are transmitted from the radio terminal to the radio base station, and ack4 is Assume that it has been lost in the radio section.

The operations from timing tl to t7 are the same as those of the radio terminal 100 and the radio base station 200 according to the present embodiment.

[0087] The radio base station receives the retransmitted packet P4 (timing t8). The wireless base station has already updated the value of LastReceiveNum to 0 0101 at the time of receiving packet P5 (timing t6). In the conventional example, the interpretation period INT is provided in the past direction.

ALL

Absent.

[0088] Therefore, as shown in FIG. 9, when the radio base station receives the 5-bit sequence number (00100) added to the retransmitted packet P4, the value of LastReceiveNum held (00 plates) It is recognized that the future direction, that is, 100100 (= 36), which is larger than 00100 (see the underlined part in the figure). As a result, the radio base station erroneously recognizes the retransmitted packet P4 as the 36th transmitted packet.

[0089] (3) Consideration of alternatives related to packet retransmission

In the embodiment described above, the power used to use the 5-bit sequence number in the entire communication sequence. To avoid the above-described problem of the conventional example, only the 13-bit sequence number instead of the 5-bit sequence number is used only when the packet is retransmitted. A plan to use is considered.

[0090] However, this method may cause another problem as follows. That is, as shown in FIG. 10, a packet P10 to which a 5-bit sequence number is added can store data of up to 7 bytes (databyte;! To 7) in the data string DB.

[0091] When resending packet P10 and using a 13-bit sequence number instead of a 5-bit sequence number, the maximum data that can be stored in packet P11 data 歹 IJDB is 6 bytes (49 bits = bits 27 to 75) It is. For this reason, 7 bytes of data cannot be stored in packet P11. Therefore, data (databyte 7) that cannot be stored in packet P11 is Packet Pll must be stored in packet P12, which is a different packet.

That is, when retransmitting the packet P10 using the 13-bit sequence number, two packets of the packet P11 and the packet P12 must be retransmitted. For this reason, the data throughput associated with retransmission may be greatly reduced. For example, if a large number of packets are lost in the wireless interval due to deterioration of the frame error rate (FER), the data throughput is reduced due to frequent retransmission of lost packets. When such a situation occurs, the data throughput at the time of retransmission is greatly reduced even though the sequence number is reduced from 13 bits to 5 bits by LSB encoding to improve the data throughput.

In this embodiment, the radio terminal 100 (encoding / decoding processing unit 105) and the radio base station 20 0 (encoding / decoding processing unit 205) also perform a 5-bit sequence when retransmitting a packet. Up to a 5-bit sequence number associated with the future direction period INT.

F

Then, encode the 13-bit sequence number into the 5-bit sequence number. For this reason, 7-byte data can be stored even when retransmitting a packet, and the above-described decrease in data throughput does not occur! /.

[0094] Further, in the present embodiment, since the 5-bit sequence number is used even when the packet is retransmitted, the same sequence number as that used when the packet is retransmitted can be used.

[0095] (Action 'effect)

According to the communication system 10, the interpretation period INT includes LastSendAckNum ± 0 (Fig. 6

ALL

Corresponds to the future direction interval NT associated with the 5-bit sequence number transmitted after the reference) and the 5-bit sequence number transmitted before LastSendAckNum ± 0.

F

Attached past direction period INT and force S are provided. In addition, the sending side is the future direction period INT

P

13-bit sequence number up to the maximum 5-bit sequence number associated with

F

Is encoded into a 5-bit sequence number.

[0096] Therefore, a 5-bit sequence number that deviates from the range of the interpretation period INT on the receiving side.

ALL

No signal is retransmitted by the sender. That is, even when a packet that stores a 5-bit sequence number is retransmitted by ARQ, it is ahead of LastSendAckNum ± 0. The past direction period INT associated with the 5-bit sequence number sent to

P

Therefore, the 5-bit sequence number can be correctly decoded into the 13-bit sequence number. [0097] In this embodiment, the future direction period INT occupies approximately half the interpretation period INT.

F ALL

Have. For this reason, while increasing the number of packets that can be transmitted without confirming ack (so-called “outstanding number”), even when the packet is retransmitted, the 5-bit sequence number can be correctly decoded into the 13-bit sequence number.

In the present embodiment, since a 5-bit sequence number is used also when a packet is retransmitted, it is possible to prevent a decrease in data throughput due to an increase in the number of packets to be retransmitted as described above.

[0099] (Other Embodiments)

As described above, the contents of the present invention have been disclosed through one embodiment of the present invention. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

[0100] For example, in the above-described embodiment, the sequence number (13-bit sequence number, 5-bit sequence number) is the force sequence number associated with the packet, the data sequence DB included in the packet, specifically, May be associated with data byte;! -7. In general, if the size of the payload PL changes when a packet is retransmitted, it is preferable to associate a sequence number with each data byte! /.

[0101] In the above-described embodiment, the future direction period INT and the past direction period INT are substantially the same.

F P

It is the same period but has a length of past direction period INT 1 future direction period INT or more.

P F

If you do.

[0102] Furthermore, in the above-described embodiment, the number of bits used for the force sequence number in which the 13-bit sequence number and the 5-bit sequence number are used may not necessarily be 13 bits and 5 bits.

[0103] As described above, the present invention naturally includes various embodiments not described herein. Accordingly, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description. [0104] The entire contents of Japanese Patent Application No. 2006-234500 (filed on August 30, 2006) are incorporated herein by reference.

Industrial applicability

[0105] As described above, the communication system, communication apparatus, and communication method according to the present invention, when automatic retransmission control such as multiple ARQ is used, only a part of the number bit string to be originally transmitted such as LSB encoding. This is useful in wireless communication such as mobile communication, because it is possible to provide more reliable decoding of the number bit string on the receiving side while using the encoding method to be transmitted.

Claims

The scope of the claims

[1] a transmitting device that encodes and transmits a partial number bit string that is a part of a number bit string to be transmitted;

Using the received partial number bit string and a reference value shared by the transmitting device and the receiving device, changing the period that is the range of the partial number bit string that can be decoded into the number bit string. A receiving device for decoding into a number bit string,

In the communication system in which automatic retransmission control of the partial number bit string is executed, the transmitting device is configured to use the latest partial number with reference to the latest partial number bit string that is the partial number bit string that the receiving device has successfully received. An encoding processor that performs the encoding for a future direction period associated with a partial number bit string transmitted after the bit string;

The receiving apparatus performs the decoding with respect to the past direction period associated with the partial number bit string transmitted from the transmitting apparatus at least before the latest partial number bit string with reference to the latest partial number bit string. A communication system including a decryption processing unit.

[2] The communication system according to claim 1, wherein the past direction period is longer than the future direction period.

[3] A period that is a range of a partial number bit string that can be decoded into the number bit string by the receiving device is configured by the future direction period and the past direction period,

The future direction period occupies approximately half of the period that is the range of the partial number bit string that the receiving device can decode into the number bit string,

The communication system according to claim 1, wherein the encoding processing unit encodes the number bit string into a partial number bit string up to a partial number bit string associated with the future direction period.

[4] The encoding processing unit, when retransmitting the partial number bit string, encodes the number bit string into a partial number bit string up to a partial number bit string associated with the future direction period. The communication system according to 1.

[5] The partial number bit string is stored in a packet,

The communication system according to any one of claims 1 to 4, wherein the partial number bit string is associated with the packet.

[6] The partial number bit string is stored in a packet,

The communication system according to any one of claims 1 to 4, wherein the partial number bit string is associated with a data string stored in the packet.

[7] A partial number bit string, which is a part of the number bit string to be transmitted, is received from the communication destination, and the received partial number bit string and the reference value shared with the communication destination are used to generate the number bit string. While decoding the number bit string while sequentially changing the period that is the range of the partial number bit string that can be decoded,

A communication apparatus that performs automatic retransmission control of the partial number bit string, wherein the period is after the latest partial number bit string with reference to the latest partial number bit string that is the partial number bit string that has been successfully received. A future direction period associated with a partial number bit string transmitted from the destination, and a past direction period associated with a partial number bit string transmitted earlier than the latest partial number bit string. The direction period has a length equal to or longer than the future direction period,

A communication apparatus including a decoding processing unit that performs the decoding for at least the past direction period with respect to the latest partial number bit string at least with respect to the latest partial number bit string.

[8] The partial number bit string received from the transmission-side communication apparatus that encodes and transmits a partial number bit string that is a part of the number bit string to be transmitted, and the received transmission-side communication apparatus Using the reference value shared by! /, And! /, It decodes to the number bit string while sequentially changing the period that is the range of the partial number bit string that can be decoded to the number bit string. With

A communication device that performs automatic retransmission control of the partial number bit string, wherein the receiving side communication device can receive normally than the latest partial number bit sequence that is the latest partial number bit sequence that is the partial number bit sequence. A communication apparatus comprising: an encoding processing unit that performs the encoding for a future direction period associated with a partial number bit string transmitted later.

[9] The future direction period is configured to occupy a period approximately half of a period that is a range of a partial number bit string that can be decoded into the number bit string by the receiving-side communication device,

9. The 1S apparatus according to claim 8, wherein the encoding processing unit encodes the number bit string into a partial number bit string up to a partial number bit string associated with the future direction period.

10. The encoding processing unit, when retransmitting the partial number bit string, encodes the number bit string into a partial number bit string with an upper limit up to a partial number bit string associated with the future direction period. 8. The communication device according to 8.

[11] The partial number bit string is stored in a packet,

The communication apparatus according to claim 7, wherein the partial number bit string is associated with the packet.

[12] The partial number bit string is stored in a packet,

11. The communication device according to claim 7, wherein the partial number bit string is associated with a data string stored in the packet.

[13] The transmission apparatus encodes the partial number bit string that is a part of the number bit string to be transmitted, and the reception apparatus receives the received partial number bit string, and the reference shared by the transmission apparatus and the reception apparatus Using the value, the number bit string is decoded while sequentially changing the period that is the range of the partial number bit string that can be decoded into the number bit string,

A communication method in which automatic retransmission control of the partial number bit string is executed between the transmitting device and the receiving device,

The transmitting device, based on the latest part number bit string that is the part number bit string that has been successfully received by the receiving apparatus, is a future direction period associated with the part number bit string that is transmitted after the latest part number bit string For the encoding process. The receiving apparatus performs the decoding with respect to the past direction period associated with the partial number bit string transmitted from the transmitting apparatus at least before the latest partial number bit string with reference to the latest partial number bit string. Step and

A communication method further comprising: