JP4688038B2 - Wireless packet communication device, communication system, and communication method - Google Patents

Description

  The present invention relates to a communication apparatus that performs wireless communication, and more particularly to a communication technique for an aggregation packet in which a plurality of wireless packets are connected.

  In packet communication, data to be exchanged between terminals is divided into fixed or variable lengths to form packets, and the formed packets are transmitted and received. The format of the packet includes a destination, data, and CRC (Cyclic Redundancy Check) as shown in FIG. The CRC is information used for checking whether or not the reception of the packet is successful on the receiving side.

  In particular, a technique for performing packet communication wirelessly is referred to as wireless packet communication. However, wireless packet communication has a higher probability of erroneous data during transmission / reception than when packet transmission / reception is performed using wired communication. For this reason, for example, in wireless packet communication using the access control method of the IEEE802.11 standard, the packet receiving terminal returns an Ack packet notifying that the packet has been successfully received to the transmission source terminal. Increase the degree.

  There are roughly two types of wireless packet communication. One is a form of direct communication between terminals (FIG. 1), and the other is a form via an access point (FIG. 2).

  In FIG. 1, when a terminal 1A transmits a data packet to another terminal 1B, the terminal 1B transmits an Ack packet to the terminal 1A when confirming that the data packet has been normally received. In FIG. 2, when the terminal 2A transmits a data packet addressed to the terminal 2B, when the access point 2C normally receives the data packet addressed to the terminal 2B, it first transmits an Ack packet to the terminal 2A. The data packet is transferred to the terminal 2B. When the terminal 2B normally receives the data packet, the terminal 2B transmits an Ack packet to the access point 2C.

  As described above, in wireless packet communication, the receiving side must always transmit one Ack packet for one data packet, so communication efficiency is likely to be lower than wired packet communication that does not use an Ack packet. .

  Therefore, in order to reduce the time for transmitting and receiving Ack packets and efficiently communicate data packets, as shown in FIG. 3, a plurality of data packets are combined (aggregated) and communicated by one large packet. A packet aggregation method has been proposed.

  An example of such a packet aggregation method is shown in Non-Patent Document 1. FIG. 4 shows a packet format of a combined packet (aggregation packet) similar to that proposed in Non-Patent Document 1. As shown in FIG. 4, the aggregation packet 4 is a combination of a plurality of data packets 4a / 4b / 4c. Between these data packets, a delimiter 4a_1 / 4b_1 / 4c_1, which is control data indicating a delimiter of each data packet, is inserted.

  FIG. 5 shows an internal configuration of a general delimiter. The delimiter 5 includes reserve information 5A, packet length information 5B immediately after the delimiter 5, CRC 5C for determining the reliability of the length information 5B, and a fixed synchronization pattern (unique pattern) 5D. . Each data area in the packet or delimiter format is called a field. For example, FIG. 5 shows a reserved field (5A), a length field (5B), a CRC field (5C), and a unique pattern. There is a field (5D).

  FIG. 6 shows a general block diagram inside a terminal that performs packet aggregation. In FIG. 6, the terminal 6 that performs packet aggregation includes an aggregation processing unit 6B_1 having a delimiter processing unit 6B_2 in the MAC layer 6B between the link layer 6A and the physical layer 6C. The aggregation processing unit 6B_1 is a function of combining a plurality of data packets, putting them in the transmission queue for aggregation packets, and transmitting them. The delimiter processing unit 6B_2 is a function that calculates a CRC from the lengths of individual data packets to be combined and generates a delimiter for each packet so that the length information and the CRC are included.

  FIG. 7 shows a state in which the access point 7D transmits an aggregation packet to the three terminals 7A / 7B / 7C using the packet aggregation technique. The access point 7D forms an aggregation packet 7E by combining packets destined for each terminal stored in its own transmission queue via a delimiter, and transmits this packet 7E to each terminal 7A / 7B / 7C. To do.

  There are the following two processing methods when each terminal 7A / 7B / 7C in FIG. 7 receives the aggregation packet 7E. These two methods may be used in combination.

  One is a method of recognizing the position of the subsequent delimiter based on the length information of each data packet stored in the delimiter 8A as shown in FIG. Each terminal in this method first reads the head delimiter 8A, calculates the CRC for the length information of the packet represented by the delimiter 8A, and determines whether the length information of the packet is correct.

  If the length information is correct as a result of the determination, the data corresponding to the length information is recognized as a packet from the aggregation packet 8. Then, the destination of the packet is checked, and if the destination of the packet is addressed to the own terminal, the packet is extracted from the aggregation packet 8 and stored in the buffer. If the destination of the packet is not addressed to the own terminal, the packet is discarded. In this manner, each delimiter in the aggregation packet 8 is processed.

  As shown in FIG. 9, another method related to the reception processing of the aggregation packet is a method of detecting the pattern in the aggregation packet using the unique pattern of the delimiter and thereby recognizing the position of the delimiter.

  According to this method, each terminal first scans the entire received aggregation packet and searches for a position that matches a unique pattern that is known to the transmission side. Next, regarding the position matched with the pattern, the matched portion is regarded as a delimiter unique pattern. Then, the CRC related to the length information described in the delimiter is calculated. When it is determined that the length information is correct, synchronization is performed with the delimiter storing the length information, and a packet associated with the delimiter is extracted from the aggregation packet.

Further, the destination of the packet extracted based on the delimiter is checked, and if it is destined for itself, reception processing is performed. If the destination of the packet is not destined for itself, discard processing is performed. In this manner, each delimiter in the aggregation packet 8 is processed.
By Adrian Stephens, "HT MAC Specification", [online], January 6, 2006, p.52-55, Enhanced Wireless Consortium, Internet <URL: http://www.enhancedwirelessconsortium.org/home/EWC_MAC_spec_V124.pdf >

  The first problem is that all of the data packets from the beginning to the end of the aggregation packet are processed regardless of the destination of the data packet, regardless of which of the two methods described above regarding the reception processing of the aggregation packet. This is the point that must be done. The reason is that the packet delimited by the delimiter cannot be recognized unless the position of each delimiter included in the aggregation packet is recognized. Therefore, packets that do not need to be received by the terminal itself are also subject to reception processing, making it difficult to improve processing efficiency.

  The second problem is that in the case of the processing method shown in FIG. 9, when the unique pattern is detected, the CRC of the data is calculated regardless of whether or not the data read during scanning is a delimiter. It is that it is easy to occur. Since wasteful reception processing leads to waste of power, improvement is desired particularly from the viewpoint of battery consumption of the terminal.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique that increases the efficiency of aggregation packet reception processing and brings about a power saving effect of a terminal.

  The communication apparatus according to the present invention includes means for concatenating a plurality of data packets to be transmitted by wireless communication to form a concatenated packet, and the length of the corresponding data packet added to the head of each data packet of the concatenated packet Means for generating first delimiter data having information regarding, and second information having information indicating one of the data packets of the data packet group added to each data packet of the predetermined data packet group in the concatenated packet Means for generating the delimiter data.

  According to the present invention, since the predetermined data packet group of the concatenated packet transmitted from the communication device is associated by the second delimiter data, the packet processing efficiency on the receiving side is improved. Thereby, power saving of the terminal can be achieved. Further, it is possible to cope with packet loss that is likely to occur in wireless communication.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 10 shows a system configuration according to the embodiment of the present invention. A system 1000 of this embodiment includes an access point 1001, a terminal 1002, a terminal 1003, and a terminal 1004, each corresponding to a communication apparatus according to the present invention.

  FIG. 11 is a block diagram schematically showing the basic functions of the access point 1001 and the terminals 1002/1003/1004 as the communication device 1101. The communication device 1101 is a device that wirelessly communicates with other communication devices via a wireless link, and has processing functions related to the physical layer 1104, the MAC layer 1103, and the link layer 1102.

  The MAC layer 1103 includes an aggregation processing unit 1105 that performs data packet aggregation processing, a delimiter processing unit 1106 that performs processing related to the conventional delimiter corresponding to the first delimiter data according to the present invention, and the second delimiter data. An extended delimiter processing unit 1107 that performs processing related to an extended delimiter described later is provided. The format of the conventional delimiter and the extended delimiter can be the same as that of the conventional delimiter described with reference to FIG. 5, but the format of the extended delimiter is not necessarily the same as that of the conventional delimiter.

  FIG. 18 shows an example of the format of an aggregation packet including an extended delimiter. The illustrated example is an example in which the extended delimiter is added only to the data packet of “destination A”. The value indicated by the “length” of the conventional delimiters 1801/1804/1806/1808/1811 corresponds to the length up to the next conventional delimiter. That is, for example, the “length” of the conventional delimiter 1801 is the sum of the length of the data packet 1802 of “destination A” and the length of the extended delimiter 1803 added thereto.

  In the present embodiment, the lengths of both the conventional delimiter and the extended delimiter are fixed, and as an example, each length is 4 bytes. Therefore, for example, if the length of the data packet 1802 is 100 bytes, the “length” of the leading conventional delimiter 1801 describes “104 bytes” obtained by adding 4 bytes to 100 bytes. Note that the lengths of both the conventional delimiter and the extended delimiter are not necessarily fixed.

  Information indicating that the extended delimiter (1803/1810) is added to the data packet in the conventional delimiter of the data packet to which the extended delimiter is added, that is, the conventional delimiter 1801/1808 related to “destination A” in FIG. Is described. The information can be expressed using, for example, a bit of a reserve field (FIG. 5: reserve 5A) in the conventional delimiter.

  The extended delimiter 1803/1810 is added to the end of the data packet 1802/1809. The example shown in FIG. 18 is an example in which the data packet group associated with the extended delimiter is the data packet group of “destination A”, and the extended delimiter (1803/1810) is added only to the data packet 1802/1809 of “destination A”. Is done.

  In the “length” of the extended delimiter, a value corresponding to the read start position of the subsequent data packet to which the same type of extended delimiter is added is described. Specifically, for example, among the data packets after the data packet 1802 in FIG. 18, the data packet of “destination A” is the data packet 1809 to which the conventional delimiter 1808 is added. In this case, the “length” described in the extended delimiter 1803 of the data packet 1802 is the length of the next “destination A” to the conventional delimiter 1808, that is, the lengths of the conventional delimiter 1804 and the data packet 1805 related to “destination B”. And the lengths of the conventional delimiter 1806 and the data packet 1807 related to “destination C”.

  FIG. 12 shows a functional configuration of the transmission system of the communication apparatus 1101 of the present embodiment. The transmission queue 1201 includes a storage area of a buffer memory associated with a plurality of priorities “0”, “1”, “2”, and “3”.

  The transmission data from the upper layer is first added with destination information by the destination information generating / adding unit 1211, and then the CRC generating / adding unit 1212 generates / adds a CRC for reception determination on the receiving side. The Thus, when data packets having the same format as the conventional one as shown in FIG. 23 are formed, they are distributed to each area of the transmission queue 1201 for each priority.

  The packet concatenation unit 1202 takes out the data packet from the queue with high priority from the transmission queue 1201, and adds the delimiter generated by the delimiter generation unit 1203 to the head of the packet. Further, when the extracted data packet is a packet corresponding to the extended delimiter, a place for describing the extended delimiter is secured at the end thereof. Note that the order of reading packets from the transmission queue 1201 does not necessarily follow the priority, and may be set as appropriate.

  The extended delimiter determining unit 1204 determines whether the destination of the packet being processed by the packet concatenating unit 1202 is for a terminal corresponding to the extended delimiter, based on information from a higher layer that manages communication between terminals. To do. Information on the determination content is referred to by the packet length calculation unit 1205 and the extended delimiter generation unit 1207.

  When the determination content of the extended delimiter determination unit 1204 indicates that the extended delimiter is not supported, the packet length calculation unit 1205 notifies the packet length itself to the delimiter generation unit 1203 and indicates that it corresponds to the extended delimiter. In this case, the packet length plus the length of the extended delimiter (4 bytes) is notified to the delimiter generation unit 1203 as the packet length.

  The CRC calculation unit 1206 obtains information about the packet length calculated by the packet length calculation unit 1205, generates a CRC for the information, and supplies the CRC to the delimiter generation unit 1203.

  The delimiter generation unit 1203 is a CRC calculation unit based on information indicating the determination contents of the extended delimiter determination unit 1204, information on the packet length calculated by the packet length calculation unit 1205 based on the information, and information on the length A conventional delimiter is generated based on the CRC information calculated by 1206.

  For each data packet included in the aggregation packet, the location information management unit 1208 manages information regarding the destination and / or priority and information regarding where the data packet is arranged in the aggregation packet.

  The extended delimiter generating unit 1207 recognizes which data packet addressed to the terminal is compatible with the extended delimiter based on the information of the extended delimiter determining unit 1204, and then manages information on the arrangement of the extended delimiter-compatible data packet as location information management. Obtained from part 1208. Based on these pieces of information, an extended delimiter is generated and passed to the packet concatenation unit 1202. The generated extended delimiter is inserted into the extended delimiter insertion position secured in advance by the packet concatenation unit 1202.

  The aggregation packet transmission queue 1210 stores the aggregation packet formed by the packet concatenation unit 1202.

  FIG. 13 shows a functional configuration of the reception system of the communication device 1101 of this embodiment. The reception buffer 1301 is a buffer in which an aggregation packet processed by the physical layer 1104 (FIG. 11) after being received from the transmission side is stored.

  The delimiter processing unit 1302 includes a packet length storage unit 1303, a CRC check unit 1304, an extended delimiter detection unit 1305, and a packet length calculation unit 1306, and processes a delimiter extracted from the aggregation packet. The packet length storage unit 1303 acquires the packet length information obtained from the delimiter processing unit 1302 in order from the first data packet in the aggregation packet, and supplies the information to the packet length calculation unit 1306. The CRC checking unit 1304 calculates the CRC for the length of each packet based on the information from the packet length storage unit 1303 and supplies it to the delimiter processing unit 1302.

  The delimiter processing unit 1302 continues the extraction process of the delimiter when the packet length is determined to be correct by the CRC in the extracted delimiter, and discards the delimiter when it is determined to be an error.

  The extended delimiter detection unit 1305 detects whether there is information in the conventional delimiter that the extended delimiter is added to the packet immediately after that, and the result is sent to the extended delimiter extraction unit 1308 and the packet length calculation unit 1306. Supply.

  Based on information from the packet length storage unit 1303 and the extended delimiter detection unit 1305, the packet length calculation unit 1306 determines that the value of the packet length storage unit 1303, i.e., the data packet, is not added to the data packet. The packet length information is output as is. If there is an extended delimiter, a value obtained by subtracting the extended delimiter length of 4 bytes from the value of the packet length storage unit 1303 is output.

  Based on the information regarding the packet length from the packet length calculation unit 1306, the packet extraction unit 1307 extracts and outputs a packet corresponding to the length information from the aggregation packet stored in the reception buffer 1301. Further, when a packet to which no extended delimiter is added is extracted, information on the position where extraction has been completed is supplied to the next packet processing start position determining unit 1309.

  The extended delimiter extraction unit 1308 extracts the data packet to which the extended delimiter is added from the aggregation packet. At the time of extraction, the address of the reception buffer 1301 corresponding to the last extraction position by the packet extraction unit 1307 is acquired, and 4 bytes are extracted therefrom as an extended delimiter and output.

  The next packet processing position determination unit 1309 determines a packet to be processed next for the aggregation packet in the reception buffer 1301. When the extended delimiter is not detected, the start position of the next packet in the reception buffer 1301 is recognized based on the information from the packet extraction unit 1307. When an extended delimiter is detected, the start position of the next packet is recognized based on information from the extended delimiter extraction unit 1308.

  The CRC checking unit 1311 calculates a CRC for each packet extracted from the aggregation packet, and supplies information indicating whether the reception is successful based on the result to the upper layer packet extracting unit 1310.

  The upper layer packet extraction unit 1310 removes the destination information added on the transmission side from each data packet extracted from the aggregation packet, and extracts a packet portion to be processed in the upper layer. At this time, a CRC check result for each packet is obtained from the CRC check unit 1311. If the check result is a successful reception, the extracted individual packet is supplied to the upper layer.

  The per-packet reception success information management unit 1312 records and manages, for each packet, information indicating whether or not the reception is successful, which is checked by the CRC check unit 1311, and supplies the information to the Ack generation unit 1313. The Ack generation unit 1313 generates an Ack packet based on the information from the per-packet reception success information management unit 1312 and supplies the Ack packet to the transmission system block.

  The transmission operation of this embodiment will be described with reference to the flowchart shown in FIG. The example used in the following description is an example in which an extended delimiter is added to a packet having the same destination among data packets constituting the aggregation packet.

  When the communication device 1101 (FIG. 11) performs processing of the MAC layer 1103 (FIG. 11), it reads one packet stored in the transmission queue 1201 (FIG. 12) (step S1), and the destination of the packet is extended. It is determined whether it corresponds to the destination of the packet to which the delimiter is to be added (step S2).

  As a result of the determination, when the destination of the packet read from the transmission queue 1201 does not correspond to the extended delimiter (step S2: NO), the communication device 1101 processes the packet in the same manner as in the conventional method related to the formation of the aggregation packet. That is, the packet length and CRC of the read packet are calculated to generate a conventional delimiter (steps S3 and S4), and the conventional delimiter is added to the packet (step S5). Then, the packet with the conventional delimiter added is concatenated to the end of the previous packet, and the concatenation position of the next packet is recognized (step S6). If the packet currently being processed is the first packet of the aggregation packet, there is no preceding packet.

  On the other hand, when the destination of the packet read from the transmission queue 1201 corresponds to the extended delimiter (step S2: YES), the communication device 1101 calculates the length of the read packet and then adds the length of the extended delimiter to the calculation result. (4 bytes) is added (step S7). Also, CRC in the packet is calculated (step S8), and a conventional delimiter is generated using the calculation result and the previously calculated packet length.

  At this time, information indicating that the packet is an addition target of the extended delimiter is set in the conventional delimiter (step S9). As a setting method, for example, there is a method of setting the reserved field (FIG. 5) of the conventional delimiter to “1”. Normally, “0” indicating that there is no value is set in this reserved field, and if it is “0”, it is discarded at the receiving terminal.

  Subsequently, the communication device 1101 adds the generated conventional delimiter to the head of the packet (step S10), and concatenates the packet with the preceding packet. Further, based on the previously calculated packet length (step S7), the connection position of the next packet is recognized (step S11). That is, the position after 4 bytes for the extended delimiter from the end of the currently connected packet is recognized as the connection position of the next packet.

  While there are packets to be linked in transmission queue 1201 (step S12: YES), communication device 1101 sequentially links the packets in the above procedure. When all the packets to be concatenated are read from the transmission queue 1201 (step S12: NO), the extended delimiter is based on the information on the destination of each concatenated packet and the position of each packet in the aggregation packet. Is generated (step S13). A value set in the extended delimiter at this time will be described later by giving a case example.

  The communication device 1101 inserts the generated extended delimiter into an area for 4 bytes secured in advance (step S14). Thereby, an aggregation packet as shown in FIG. 18 is formed. The example shown in FIG. 18 is an example in which the extended delimiter 1803/1810 is added only to the data packet 1802/1809 of “destination A” as described above. Specifically, for example, in the case of the data packet 1802 of “destination A”, the conventional delimiter 1801 is added to the head thereof, and the extended delimiter 1803 is added to the tail thereof. Immediately after this extended delimiter 1803, the conventional delimiter 1804 of the data packet 1805 of “destination B” is connected.

  When the communication device 1101 forms the aggregation packet as described above, it stores it in the aggregation packet transmission queue 1210 (FIG. 12) (step S15). The aggregation packet stored in the queue is transmitted by wireless communication through the processing of the physical layer 1104 (FIG. 11).

  Next, the reception operation of the communication device 1101 will be described with reference to the flowchart shown in FIG. The aggregation packet received and processed by the physical layer 1104 of the communication device 1101 is passed to the MAC layer 1103. When the aggregation packet is stored in the reception buffer 1301 (FIG. 13) (step S31: YES), the communication device 1101 first reads out the conventional delimiter added to the first packet by the delimiter processing unit 1302 (step S32). .

  The communication device 1101 extracts information on the packet length from the conventional delimiter read from the buffer, and stores it in the packet length storage unit 1303. Further, a CRC is calculated for the information relating to the packet length, and it is determined whether or not this information is correct (step S33).

  If the information on the packet length is not appropriate as a result of the determination (step S33: NO), the conventional delimiter is searched by the same method as the conventional one. That is, the conventional delimiter is searched for the unprocessed portion after the currently processed portion of the currently processed aggregation packet by matching the unique pattern in the conventional delimiter (step S34). As a result, when a pattern that matches the unique pattern is detected (step S35: YES), the part is regarded as a conventional delimiter, and a part related to length information is extracted, and a CRC for the part is calculated ( Step S36).

  On the other hand, when the CRC check result of the conventional delimiter read from the reception buffer 1301 is appropriate (step S33: YES), the communication device 1101 refers to the reserved field of the conventional delimiter and adds the extended delimiter to the packet. It is determined whether or not it has been performed (step S37). That is, when the value of the reserve field is “0”, it is determined that the extended delimiter is not added when the value is “1”.

  If no extended delimiter is added as a result of the above determination (step S37: NO), the length information extracted from the conventional delimiter is extracted as a packet immediately after the conventional delimiter (step S38). Thereafter, when there is no information indicating that the extended delimiter exists, the same processing is repeated, and the processing is sequentially performed from the head of the aggregation packet.

  If it is determined that an extended delimiter exists (step S37: YES), data having a length obtained by subtracting 4 bytes from the length indicated in the length field of the conventional delimiter is extracted as a packet immediately after the conventional delimiter ( Step S39) and hand it over to the upper layer. Then, the extended delimiter extraction unit 1308 extracts the next 4 bytes of data as an extended delimiter (step S40).

  Subsequently, it is determined whether there is information indicating that the extracted extended delimiter is the last packet of the same destination (step S41). This information will be described in detail later. For example, in the case where the extended delimiter is added only to the packet of “destination A”, the packet currently being processed is the last packet of “destination A” in the aggregation packet. Is set in the extended delimiter.

  As a result of the above determination, when there is information that the packet is the last packet of the same destination (step S41: YES), the communication device 1101 receives the aggregation packet even if an unprocessed aggregation packet exists in the reception buffer 1301. The process ends at that point.

  Further, when the above information is not present (step S41: YES), that is, when a packet with the same destination such as “destination A” follows, the next packet processing start position determination unit 1309 checks the length field of the extended delimiter. Then, the next processing position is determined in the unprocessed aggregation packet in the reception buffer (step S42). This processing position is a position for extracting a subsequent packet having the same destination, and is, for example, the head of the packet or the head of a conventional delimiter added to the packet. Then, the packet is extracted by the above procedure (step S39).

  FIG. 16 shows an example of the format of the aggregation packet of this embodiment. An example of the terminal operation when the aggregation packet 1600 in FIG. 16 is applied to the system 1000 in FIG. 10 will be described.

  In the system 1000, the aggregation packet 1600 is used as a packet transmitted from the access point 1001 to each terminal 1002/1003/1004. As shown in FIG. 16, an extended delimiter (1603/1608/1611) is inserted at the end of each of “destination A” packets 1602/1607/1610 included in the aggregation packet 1600.

  In the length field of the extended delimiter, a value corresponding to the pointer in the reception buffer 1301 to be processed next is set. For example, in the case of the packet 1602 of the first “destination A” in the aggregation packet 1600, the length field of the extended delimiter 1603 added to the packet 1602 of the subsequent packet having the same “destination A” A value that indicates the head position is set.

  Also, the extended delimiter 1608 added to the “destination A” packet 1607 is set to indicate the subsequent “destination A” packet 1610. If there is no more “destination A” packet, information indicating that there is no “destination A” packet in the length field of the extended delimiter 1611 of this packet 1610 is set. . As the setting method, for example, “0” is set in the length field of the extended delimiter 1611.

  Similarly, information indicating the position of the next “destination C” packet 1618 is set in the extended delimiter 1614 added to the “destination C” packet 1613.

  In the above description, a case where a plurality of destination packets are mixed in one aggregation packet and the same destination packet group is associated by an extended delimiter has been described. However, other parameters other than the destination, for example, priority regarding packet transmission Degrees may be used. In other words, it is a case in which packet groups having the same priority in the aggregation packet are associated by an extended delimiter. Further, packets having the same destination and the same priority, or other same radio parameters, and combinations thereof may be associated by an extended delimiter. Further, the parameter values to be associated do not necessarily have to be the same.

  In the present embodiment, the position indicated by the extended delimiter is a position related to the packet subsequent to the extended delimiter, but instead of this, the beginning or end of the conventional delimiter of the packet preceding the extended delimiter, or It may be the beginning or end of the extended delimiter in the preceding stage, or the beginning or end of the preceding packet itself. It is assumed that the position pointed to by the extended delimiter can point to an arbitrary position so that processing efficiency is improved on the receiving side.

  According to the embodiment described above, the extended delimiter-compatible device does not need to process the entire received aggregation packet, so that the processing efficiency can be improved. This is convenient from the viewpoint of power saving of the terminal.

  FIG. 17 shows another example of the format of the aggregation packet. An example of terminal operation when the illustrated aggregation packet 1700 is applied to the system 1000 of FIG. 10 will be described.

  The format shown in FIG. 17 takes a form in which extended delimiters are regularly inserted into an aggregation packet when a plurality of packets are concatenated. In each extended delimiter, a field value is set so as to indicate the position of each of the two extended delimiters.

  Specifically, for example, the instruction target of the extended delimiter 1703 of the packet 1702 is the packet 1708 that is two backwards or the conventional delimiter 1707 thereof. The instruction object of the extended delimiter 1706 of the packet 1705 next to the packet 1702 is the packet 1711 or its conventional delimiter 1710.

  The aggregation packet 1700 in FIG. 17 includes two types of packets. That is, one is a system including a packet 1702, a packet 1708, and a packet 1714, and the other is a system including a packet 1705, a packet 1711, and a packet 1717.

  The purpose of associating packets of the same system with an extended delimiter in this way is to improve the efficiency of reception processing and to improve resistance to data errors on the reception side. Since the terminal that has received the aggregation packet 1700 as shown in the figure can process the above-mentioned two systems of packets in parallel, the processing becomes efficient.

  Further, for example, when the receiving side finds that the conventional delimiter 1710 of the packet 1711 has an error, the length of the packet 1711 becomes unknown. In this case, the packet 1711 cannot be extracted, and the head position of the subsequent conventional delimiter 1713 is unknown. In such a case, according to the present embodiment, since the position of the conventional delimiter 1713 is indicated by the preceding extended delimiter 1706, the process is resumed from the packet 1714 without performing the matching process using the unique pattern as in the conventional case. it can.

  A method of creating a plurality of packet group systems by the extended delimiter, and the insertion form and insertion frequency of the extended delimiter may be adjusted according to the transmission form of the aggregation packet to be transmitted. For example, the longer the overall length of the aggregation packet, the higher the probability that the conventional delimiter will be erroneous due to disturbances such as thermal noise, and consequently the packet loss rate is increased. Therefore, the insertion frequency of the extended delimiter is increased as the overall length of the aggregation packet is longer. Conversely, the shorter the aggregation packet, the lower the packet loss rate, so the frequency of inserting the extended delimiter is reduced.

  The insertion frequency of the extended delimiter may be adjusted according to the modulation format, unit frequency, the number of transmission information bits per unit time, and the like. For example, the higher the number of transmission information bits per unit frequency and time, the higher the probability that the conventional delimiter will be mistaken in the middle of the aggregation packet due to disturbance such as thermal noise. In this case, since the packet loss rate becomes high, the insertion frequency of the extended delimiter is increased. On the other hand, the lower the number of transmission information bits per unit frequency and time, the lower the packet loss rate, so the frequency of inserting extended delimiters is reduced.

  The insertion frequency of the extended delimiter may be adjusted according to the reception success probability derived from an Ack packet indicating successful packet reception. For example, the lower the packet reception success probability, the higher the probability that the aggregation packet will be erroneous in the middle due to disturbance such as thermal noise. As a result, the packet loss rate is increased, so that the insertion frequency of the extended delimiter is increased. On the other hand, the higher the packet reception success probability is, the lower the packet loss rate is, so the frequency of inserting the extended delimiter is reduced.

  Further, the insertion frequency of the extended delimiter may be adjusted according to the communication quality based on the received power of the packet transmitted from the communication destination. For example, the lower the received power of the packet, the higher the probability that the conventional delimiter will be mistaken in the middle of the aggregation packet due to disturbance such as thermal noise. As a result, the packet loss rate is increased, so that the insertion frequency of the extended delimiter is increased. On the other hand, the higher the received power of the packet, the lower the packet loss rate.

  In addition, about the adjustment method of the insertion frequency of an extended delimiter, you may optimize combining the said several method. The adjustment target is not limited to the insertion frequency of the extended delimiter but may be the insertion position. For example, in an environment where errors are likely to occur in data relatively behind the aggregation packet, control is performed so that an extended delimiter is inserted intensively behind the aggregation packet.

  The above embodiment will be described in detail using specific examples. FIG. 19 shows the system configuration of this embodiment. The access point 1901 of the system 1900 of the present embodiment transmits an aggregation packet to the four terminals 1902/1903/1904/1905. Among these terminals, terminals 1902 (“terminal A”) and terminal 1903 (“terminal B”) can process the extended delimiter.

  FIG. 20 shows an example of an aggregation packet format applied to the system 1900 of FIG. FIG. 21 shows an example of reception processing of a terminal that has received an aggregation packet applied to the system 1900 of FIG. FIG. 22 shows an example of packet extraction processing at a terminal that receives an aggregation packet applied to the system 1900 of FIG. 19 and an example of comparison of power consumption at that time.

  Here, it is assumed that packets to all terminals (1902/1903/1904/1905) are stored in the transmission queue of the access point 1901. Further, it is assumed that the access point 1901 is notified in advance from the terminal 1902 and the terminal 1903 that both terminals are terminals capable of processing the extended delimiter. In order to facilitate the following description, it is assumed that the aggregation packet includes two data packets destined for each terminal, each having a size of 100 bytes.

  The access point 1901 connects packets to each terminal in a form as shown in FIG. 4-byte conventional delimiters 2001/2004/2007/2009/2011/2014/2017/2019 are added to the head of each 100-byte packet 2002/2005/2008/2010/2012/2015/2018/2020. . Further, each packet “Destination A” and “Destination B” 2002/2005/2012/2015 corresponding to the terminal 1902 and the terminal 1903 capable of processing the extended delimiter has a 4-byte extended delimiter 2003/2006 at the end thereof. / 2013/2016 is added.

  In the length field of the conventional delimiter of “destination A” and “destination B” to which the extended delimiter is added, the sum of the length “100 bytes” of the packet and the length of the extended delimiter “4 bytes” “104”. Byte "is set. In addition, in the case of the conventional delimiters “destination C” and “destination D” to which no extended delimiter is added, the length “100 bytes” of only the packet is set in each length field.

  In each extended delimiter of the “destination A” packet 2002 and the “destination B” packet 2005, information on the length to the subsequent packet having the same destination is set. Specifically, the extended delimiter 2003 of the “destination A” packet 2002 is set to “316 bytes” that is the length from the immediately preceding conventional delimiter 2004 to the beginning of the next “destination A” conventional delimiter 2011. Is done. Similarly, in the extended delimiter 2006 of the packet 2005 of “destination B”, “316 bytes” that is the length from immediately after that to the conventional delimiter 2014 of the next “destination B” is set.

  Further, as described above, a value indicating the presence of the extended delimiter is set in the conventional delimiter of the packet to which the extended delimiter is added. In the example of FIG. 20, “1” is set in the reserved fields of the conventional delimiters 2001/2004/2011/2014 of “destination A” and “destination B”, respectively. “0” is set in the conventional delimiters of other destinations.

  The extended delimiter 2013/2016 added to the second packet 2012/2015 of “Destination A” and “Destination B” indicates that there are no “Destination A” and “Destination B” packets after each. “0 byte” as a value to be represented is set in the length field.

  The access point 1901 transmits the aggregation packet configured as described above to the four terminals 1902/1903/1904/1905. The processing of each terminal that has received the transmitted aggregation packet differs depending on whether or not the terminal can process the extended delimiter.

  The reception process of each terminal will be described with reference to FIG. First, regarding the operation of a terminal that does not support the extended delimiter, terminal 1904 (“terminal C”) is taken as an example. When the terminal 1904 receives the aggregation packet, the terminal 1904 interprets the first 4 bytes as a conventional delimiter and reads the length field. In the length field, “104 bytes” including the extended delimiter is set. When the terminal 1904 reads 104 bytes of data, that is, data including the packet of “destination A”, and recognizes that the destination is not its own terminal, the terminal 1904 sets the reading position by 104 bytes to shift to processing of the next packet. Proceed.

  The terminal 1904 recognizes data from the new reading position as the next conventional delimiter. This conventional delimiter relates to the packet of “destination B”. The terminal 1904 reads 104 bytes of data in the same manner as described above, and when it recognizes that it is not a packet addressed to itself, advances the pointer to the next reading position.

  The terminal 1904 recognizes that the new 4-byte data is the conventional delimiter, and reads “100 bytes” of data set in the length field. This data is a packet of “destination C”. When the terminal 1904 recognizes that the read data is a packet addressed to itself, the terminal 1904 extracts the data. Similarly, the terminal 1904 extracts the packet of “destination C” by proceeding to the end of the aggregation packet.

  As described above, the terminal (1904/1905) that cannot process the extended delimiter processes all the packets of the aggregation packet in order to extract the packet addressed to itself.

  Next, reception processing of a terminal capable of processing the extended delimiter will be described by taking terminal 1902 (“terminal A”) as an example. When the terminal 1902 receives the aggregation packet, the terminal 1902 interprets the first 4 bytes of the aggregation packet as a conventional delimiter, and reads data corresponding to the length field value “104 bytes”. Up to this point, the processing is the same as that of the terminal 1904 (“terminal C”) described above.

  When the terminal 1902 recognizes that the read data includes a packet addressed to itself (“destination A”) and the value of the reserved field of the conventional delimiter is “1”, the terminal 1902 reads 104 bytes. 100 bytes of data are extracted from the data by excluding 4 bytes of the extended delimiter. Then, the value “316 bytes” in the length field of the extended delimiter is recognized, and the read start position for the aggregation packet is advanced by 316 bytes. As a result, the pointer is placed at the head of the conventional delimiter of the next packet having “destination A”.

  Based on the newly read conventional delimiter, the terminal 1902 extracts the “destination A” packet in the same manner as described above, and checks the length field of the extended delimiter added to the packet. Its value is “0 bytes”. The terminal 1902 recognizes that there is no packet of the same system, that is, the packet of “destination A” in the remaining aggregation packets, and ends the processing at this point.

  Thus, in the case of a terminal (1902/1903) that can process the extended delimiter, the processing target in the received aggregation packet is only the packet addressed to the terminal itself. Therefore, it is not necessary to read out all the packets of the aggregation packet.

  More specifically, as shown in FIG. 21, terminal A (terminal 1902) that can process the extended delimiter processes only the packet of “destination A” after the first packet of the received aggregation packet, and the others. Are not read out and discarded, so that only the packets [1] and [5] remain in the buffer of terminal A after reception processing. Similarly, in the case of terminal B (terminal 1903) that can process the extended delimiter, only the packets [2] and [6] destined for the own terminal are stored in the buffer.

  On the other hand, since the terminal C (terminal 1904) and the terminal D (terminal 1905) cannot process the extended delimiter, it is necessary to process all the packets ([1] to [8]) in the received aggregation packet.

  Referring to FIG. 22, the packet extraction processing of the four terminals 1902/1903/1904/1905 (terminal A, terminal B, terminal C, terminal D) in FIG. 20 and comparison of power consumption at that time will be described.

  A terminal that does not support the extended delimiter, such as terminal C (1904), needs to process the entire aggregation packet. Therefore, terminal C and terminal D (1905) consume power for processing from the beginning to the end of the aggregation packet.

  On the other hand, a terminal such as terminal A (1902), which is an extended delimiter-compatible device, processes only the packet addressed to itself by using the extended delimiter set in the received aggregation packet, and ends the reception process. be able to. Accordingly, power consumption can be reduced by the amount of processing of packets addressed to other terminals.

It is explanatory drawing regarding the direct communication form between the terminals in general wireless packet communication. It is explanatory drawing regarding the communication form via the access point in general wireless packet communication. It is explanatory drawing regarding the communication form of the aggregation packet in general wireless packet communication. It is explanatory drawing regarding the format of a general aggregation packet. It is explanatory drawing regarding the format of a general delimiter. It is a block diagram which shows the function structure of the terminal which handles an aggregation packet in general radio | wireless packet communication. It is explanatory drawing regarding the communication form of the aggregation packet via the access point in general wireless packet communication. It is explanatory drawing regarding the example of a general aggregation packet. It is explanatory drawing regarding the process of the aggregation packet by the receiving side in general radio | wireless packet communication. It is explanatory drawing regarding the system configuration | structure of embodiment of this invention. It is a block diagram which shows the function structure of the communication apparatus of embodiment. It is a block diagram which shows the function structure of the transmission system of the communication apparatus of embodiment. It is a block diagram which shows the function structure of the receiving system of the communication apparatus of embodiment. It is a flowchart regarding the transmission processing of the embodiment. It is a flowchart regarding the reception process of embodiment. It is explanatory drawing regarding the example of the aggregation packet in embodiment. It is explanatory drawing regarding the other example of the aggregation packet in embodiment. It is explanatory drawing regarding the basic format of the aggregation packet in embodiment. It is explanatory drawing regarding the example of the system configuration | structure of one Example of embodiment. It is explanatory drawing regarding the parameter set to the aggregation packet of one Example of embodiment. It is explanatory drawing regarding the reception process of the aggregation packet in one Example of embodiment. It is explanatory drawing regarding the power consumption in the reception process of one Example of embodiment. It is explanatory drawing regarding the format of the data packet in general radio | wireless packet communication.

Explanation of symbols

1103 Aggregation processor
1201: Transmission queue, 1202: Packet concatenation unit, 1203: Delimiter generation unit, 1204: Extended delimiter determination unit, 1205: Packet length calculation unit, 1206: CRC calculation unit, 1207: Extended delimiter generation unit, 1208: Location information management unit 1210: Aggregation packet transmission queue, 1211: Destination information generation / addition unit, 1212: CRC generation / addition unit

Claims (22)

Means for concatenating a plurality of packets to be transmitted by wireless communication to form a concatenated packet;
Means for generating first delimiter data attached to each packet of the concatenated packet and having information on the length of the corresponding packet;
Means for generating second delimiter data added to each packet of the predetermined packet group in the concatenated packet and having information indicating any packet of the packet group.   2. The communication apparatus according to claim 1, wherein the second delimiter data is added to a packet group to which the same destination is given.   3. The communication apparatus according to claim 1, wherein the second delimiter data is added to a packet group given the same priority regarding transmission.   The communication apparatus according to any one of claims 1 to 3, wherein a ratio of the second delimiter data to the concatenated packet is determined according to an overall length of the concatenated packet.   5. The communication apparatus according to claim 1, wherein a ratio of the second delimiter data to the concatenated packet is determined in accordance with a modulation format of wireless communication.   The communication apparatus according to claim 1, wherein a ratio of the second delimiter data to the concatenated packet is determined according to communication quality.   The communication apparatus according to claim 1, wherein a ratio of the second delimiter data to the concatenated packet is determined in accordance with a packet reception success rate in the opposite station.   The communication according to any one of claims 1 to 7, wherein information on whether or not the second delimiter data is added to each packet of the concatenated packet is described in the first delimiter data of each packet. apparatus.   9. The communication apparatus according to claim 1, wherein the packet indicated by the second delimiter data is a packet subsequent to the second delimiter data. Means for detecting whether or not the second delimiter data is added to the concatenated packet received by wireless communication;
10. The apparatus according to claim 1, further comprising: means for recognizing a packet indicated by the second delimiter data detected from the concatenated packet and extracting the packet from the concatenated packet. Communication device.   A program that causes a computer to function as the communication device according to any one of claims 1 to 10.   A communication system comprising: the communication device according to claim 1; and the communication device according to claim 10. A communication device that performs wireless communication
Concatenating a plurality of packets to be transmitted by wireless communication to form a concatenated packet;
Generating first delimiter data added to each packet of the concatenated packet and having information regarding the length of the corresponding packet;
Generating a second delimiter data added to each packet of the predetermined packet group in the concatenated packet and having information indicating any packet of the packet group.   The communication method according to claim 13, wherein the communication device adds the second delimiter data to a packet group to which the same destination is given.   15. The communication method according to claim 13 or 14, wherein the communication device adds the second delimiter data to a packet group given the same priority regarding transmission.   The communication method according to any one of claims 13 to 15, wherein the communication device determines a ratio of the second delimiter data to a concatenated packet according to an overall length of the concatenated packet.   The communication method according to any one of claims 13 to 16, wherein the communication device determines a ratio of the second delimiter data to a concatenated packet in accordance with a modulation format of wireless communication.   The communication method according to any one of claims 13 to 17, wherein the communication device determines a ratio of the second delimiter data to a concatenated packet according to communication quality.   19. The communication according to claim 13, wherein the communication device determines a ratio of the second delimiter data with respect to a concatenated packet according to a success rate of packet reception at the opposite station. Method.   20. The communication device according to claim 13, wherein the communication device describes information on whether or not the second delimiter data is added to each packet of the concatenated packet in the first delimiter data of each packet. The communication method according to the item.   21. The communication method according to claim 13, wherein the communication device sets a packet indicated by the second delimiter data as a packet subsequent to the second delimiter data. The communication device further comprises:
Detecting whether or not the second delimiter data is added to the concatenated packet received by wireless communication;
The step of recognizing a packet indicated by second delimiter data detected from the concatenated packet and extracting the packet from the concatenated packet is performed. Communication method.

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