WO2015088018A1 - Multi-hop wireless device and multi-hop wireless system - Google Patents

Multi-hop wireless device and multi-hop wireless system Download PDF

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WO2015088018A1
WO2015088018A1 PCT/JP2014/083019 JP2014083019W WO2015088018A1 WO 2015088018 A1 WO2015088018 A1 WO 2015088018A1 JP 2014083019 W JP2014083019 W JP 2014083019W WO 2015088018 A1 WO2015088018 A1 WO 2015088018A1
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data
transmission
hop
time
terminal
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French (fr)
Japanese (ja)
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渡辺　正浩
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三菱電機株式会社
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0808—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA]

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  • the present invention relates to a multihop radio apparatus and a multihop radio system that control a backoff time of a relay terminal in a flow of radio multihop transfer.
  • Non-Patent Document 1 As a conventional technique related to wireless multi-hop transfer, for example, there is a method shown in Non-Patent Document 1.
  • the wireless packet communication in Non-Patent Document 1 is a communication form adopted in various systems including a wireless LAN, and standardization of the wireless LAN standard is being promoted by the IEEE 802.11 committee.
  • One of the communication modes is an infrastructure mode, which forms a wireless network formed by wirelessly connecting wireless terminals to an AP (access point).
  • the method disclosed in Non-Patent Document 1 is a method related to communication control between an AP (access point) and a terminal.
  • Non-Patent Document 2 introduces priority control in order to transmit real-time traffic such as voice and video with high quality.
  • traffic input to an AP access point
  • AP access point
  • Priorities are set for each queue, and transmission control is performed so that audio and video traffic is transmitted with priority.
  • Patent Document 1 discloses a radio base station and multi-hop control in which carrier sense is given priority over other multi-hop transfer flows when multi-hop transfer is performed for flows that require real traffic such as video and audio. The method is shown.
  • IEEE 802.11 Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications”, IEEE STD 802.11, August 1999 IEEE802.11 “Medium Access Control (MAC) Quality Service Enhancements, January 2005
  • Non-Patent Document 1 the transfer procedure (relay method) in the flow of multihop transfer of data frames is not defined.
  • the method disclosed in Non-Patent Document 2 is a method related to priority control according to the type of data. Like Non-Patent Document 1, it is a method related to communication control between an AP (access point) and a terminal. Yes, the transfer procedure (relay method) in the flow of multi-hop transfer of data frames is not defined.
  • the present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a multi-hop radio apparatus and a multi-hop radio system that can improve transfer efficiency in a multi-hop transfer flow. It is said.
  • the multi-hop wireless device transmits data after waiting for a set back-off time when a channel for transmitting data is idle, and multi-hop transfer of data with other devices
  • the back-off time is set to be smaller as the data transmission to the device having a smaller number of multi-hop transfers is performed. Thereby, the data arrival rate in the flow of each multihop transfer can be improved.
  • FIG. 1 is a block diagram showing a multihop radio apparatus according to Embodiment 1 of the present invention.
  • the multihop radio apparatus includes a transmission / reception processing unit 100, a transmission buffer unit 200, a packet generation unit 210, a header removal unit 300, a data processing unit 310, a transmission control unit 400, a routing table management unit 410, and a retransmission control unit. 420 is provided.
  • the transmission / reception processing unit 100 includes a modulation unit 110, a transmission unit 120, an antenna 130, a reception unit 140, a demodulation unit 150, and a carrier detection unit 160, and is a processing unit that performs transmission / reception of data with other terminals.
  • the radio signal received via the antenna 130 is input to the transmission / reception processing unit 100.
  • the receiving unit 140 performs reception processing including frequency conversion, filtering, quadrature detection, and AD (Analog to Digital) conversion on the input radio signal.
  • a radio signal on the radio propagation path is always input to the receiving unit 140, and an RSSI (Received Signal Strength Indicator) signal representing the strength of the received signal in a predetermined frequency channel of the radio signal is a carrier. It is output to the detection unit 160.
  • the reception unit 140 receives a radio signal, the baseband signal subjected to reception processing is output to the demodulation unit 150.
  • the carrier detection unit 160 determines the state of a predetermined frequency channel using the RSSI signal input from the reception unit 140. When the RSSI signal is below a predetermined threshold over a certain period, it is determined that the frequency channel is idle, and when it is above the threshold, it is determined that the frequency channel is busy. This determination result is notified to the transmission control unit 400 as a carrier sense result.
  • Demodulation section 150 performs demodulation processing on the baseband signal that has been subjected to reception processing by reception section 140, and outputs the result to header removal section 300 as a received packet.
  • the header removal unit 300 analyzes the control information included in the header of the received packet, discards the received packet if the destination address does not match the address of the own terminal, and removes the header if the destination address matches, and removes the data frame Is extracted and output to the data processing unit 310.
  • the data processing unit 310 outputs normal data as received data to a device such as a computer connected to the terminal with respect to the data frame from the header removal unit 300. Further, data relating to network information such as a hello packet is output to the routing table management unit 410. Further, an ACK (ACKnowledge) signal for transmission data is output to retransmission control section 420.
  • a device such as a computer connected to the terminal with respect to the data frame from the header removal unit 300.
  • data relating to network information such as a hello packet is output to the routing table management unit 410.
  • an ACK (ACKnowledge) signal for transmission data is output to retransmission control section 420.
  • the routing table management unit 410 manages wireless network-related information between its own terminal and peripheral terminals. For example, a terminal that can be directly transmitted / received, a terminal that can be transmitted / received by multi-hop transfer, and the number of multi-hop transfers, The RSSI information and the like when the hello packet is received are represented by a routing table. Details of the routing table will be described later with reference to FIG.
  • the transmission buffer unit 200 When transmission data is input from a device such as a computer connected to its own terminal, the transmission buffer unit 200 notifies the transmission control unit 400 of the input of a data frame, and information about the data frame (number of data frames, data Size, transmission source (generating terminal), transmission destination (target terminal) address, etc.) are sequentially output to the transmission control unit 400.
  • retransmission control section 420 information on transmission data output from transmission buffer section 200 to packet generation section 210 (number of data frames, data size, sequence number, transmission source (generating terminal), transmission destination (target terminal) address, etc. ) And time, information on the ACK signal from the data processing unit 310 (ACK identification header, address of transmission source (generating terminal), etc.), and time, it is determined whether transmission data is received, and the result is transmitted to the transmission control unit. 400 is notified. If the ACK signal arrives within the predetermined time, the transmission data is notified to the transmission control unit 400 as having been successfully received. On the other hand, if the ACK signal does not reach within the predetermined time, the transmission data is notified to the transmission control unit 400 as reception failure.
  • the transmission control unit 400 determines whether the transmission control process can be started based on the information regarding the data frame from the transmission buffer unit 200 and the carrier sense result from the carrier detection unit 160. When a data frame is input to the transmission buffer unit 200 and the frequency channel is empty, transmission control processing is started. In other cases, the transmission control process is not started.
  • the number of multihop transfers and the adjacent terminals that can be directly transferred from the routing table of the routing table management unit 410 The address and RSSI information are acquired, and the number of slots for backoff is assigned.
  • the back-off time is expressed by multiplying the number of slots and the slot time (usually symbol time).
  • This back-off time is set to a relatively large value for a relay terminal (device on the transmission source side) on the transmission source (source terminal) side with a relatively large number of multi-hop transfers, and the multi-hop on the transmission destination (target terminal) side.
  • a relatively small value is set for a relay terminal (device on the transmission destination side) having a relatively small number of transfers. Therefore, a relay terminal on the transmission destination (target terminal) side gives priority to a larger data transfer amount per unit time.
  • RSSI information of an adjacent terminal may be added. Specifically, a relatively small value is set when the RSSI is relatively large and the radio wave propagation situation is good, and a relatively large value is set when the RSSI is relatively small and the radio wave propagation situation is not good.
  • the packet arrival rate is lowered. Therefore, the priority of this section is lowered, so that traffic is reduced and a relatively strong load is not applied.
  • the back-off time is set by combining the back-off time based on the number of multi-hop transfers and the back-off time based on RSSI. As a result, finer settings can be made in consideration of radio wave propagation conditions.
  • the retransmission control unit 420 determines that reception of the transmission data of the transmission / reception processing unit 100 by the transmission destination device has failed, the retransmission control unit 420 retransmits the transmission data with the same sequence number.
  • the number of slots is increased for backoff to increase the entire backoff time.
  • the number of slots is reduced for backoff to reduce the entire backoff time. In this way, the maximum throughput according to the traffic situation can be obtained by changing the entire range of the back-off time from the retransmission situation.
  • the transmission control unit 400 outputs the data frame accumulated at the head of the transmission buffer unit 200 to the packet generation unit 210 when the back-off time set by the transmission control process is counted down to zero. If the RSSI information is equal to or greater than the threshold value from the carrier detection unit 160 during the countdown, the frequency channel is determined to be busy, and the countdown is temporarily stopped. Thereafter, when the RSSI information becomes equal to or less than the threshold value, it is determined that the frequency channel is in an empty state, and countdown is started again.
  • the packet generation unit 210 obtains the routing table information of the routing table management unit 410 from the transmission control unit 400, and transmits the destination (target terminal) address and transmission source (occurrence).
  • a wireless packet is generated by adding a header and an error detection code composed of control information such as a terminal) address and an address of an adjacent terminal that can be directly transmitted and received during multi-hop transmission.
  • the generated wireless packet is subjected to modulation processing by the modulation unit 110, and subjected to transmission processing including DA (Digital to Analog) conversion, frequency conversion, filtering, and power amplification by the transmission unit 120. Sent.
  • DA Digital to Analog
  • FIG. 2 is an explanatory diagram of a routing table of each multi-hop wireless device in the multi-hop wireless system according to the first embodiment of the present invention.
  • a case will be described in which six terminals from the terminal 1 to the terminal 6 are arranged in a straight line to perform multihop transfer.
  • each terminal can communicate only with an adjacent terminal.
  • the routing table of each terminal includes an original (org) indicating its own terminal, a gateway (gw) indicating an adjacent terminal, a destination (dst) indicating a transmission source (generating terminal) and a transmission destination (target terminal), and a multipoint at that time
  • a hop indicating the number of hops and RSSI information (rssi) when a hello packet is received from an adjacent terminal are managed.
  • a data frame (not shown) stores information indicating a source (source terminal) that is a source of data and destination indicating a destination (target terminal). Therefore, the data generated at the transmission source (generation terminal) is multi-hop transferred by each terminal to the transmission destination terminal (target terminal) by relaying the adjacent terminal according to its own routing table.
  • the terminal 1 when data is transferred from the source terminal 1 to the destination terminal 6 in a multi-hop manner, first, if the terminal 1 transfers data to the adjacent terminal 2 using its own routing table, the destination is transmitted in five hops. Data can be delivered to the terminal 6. Next, if the terminal 2 transfers the data to the adjacent terminal 3 by using its own routing table, the data can be delivered to the destination terminal 6 in 4 hops. Similarly, if the terminal 3 transfers the data to the adjacent terminal 4 by using its own routing table, the data can be delivered to the destination terminal 6 with three hops. Similarly, if the terminal 4 transfers data to the adjacent terminal 5 using its own routing table, it can deliver the data to the destination terminal 6 in two hops. Finally, the terminal 5 can deliver data in one hop because the destination terminal 6 is an adjacent terminal according to its own routing table. From such a series of relationships, the transmission source terminal 1 can deliver data to the transmission destination terminal 6 by multihop transfer via the relay terminal.
  • FIG. 3 is an explanatory diagram showing a backoff time calculation method according to Embodiment 1 of the present invention.
  • the back-off time is calculated as the sum of a value considering the number of hops and a value considering RSSI.
  • the maximum value of the number of back-off slots: CW (Contention Window) max may be set to 1023 as in the non-patent document 1 of the prior art. Further, a value having a sufficient margin as compared with the number of peripheral terminals may be set.
  • the CWmax value is set to a value larger than 1023.
  • the number of reception failure notifications from the retransmission control unit 420 decreases and the number of retransmissions in a certain time decreases, it is determined that the traffic is in a low state and the backoff state is increased.
  • Maximum number of slots CWmax value is set to a value smaller than 1023.
  • Each relay terminal obtains information on the number of hops to the transmission source (generating terminal) and the number of hops to the transmission destination (target terminal) by using its own routing table for the data generated at the transmission source (generating terminal), Know the total number of hops in a multi-hop transfer.
  • the relay terminal of Example 1 is random from a range obtained by multiplying CW (Contention Window) max by 0 to ⁇ (the number of hops to the destination (target terminal)) / (the number of all hops) ⁇ . Select a value.
  • the relay terminal of Example 2 sets the CW (Contention Window) max to ⁇ number of hops to the destination (target terminal) ⁇ 1) / number of all hops ⁇ to ⁇ number of hops from the destination (target terminal) / all hops] A random value is selected from the range multiplied by the number ⁇ .
  • Each relay terminal acquires RSSI information with an adjacent terminal from its own routing table and multiplies an arbitrary coefficient: -k.
  • the value of is set. Thereby, when the radio wave propagation state is good, a value with a relatively small back-off time is selected to increase the priority.
  • k is multiplied by an arbitrary coefficient: k from the weighting degree with the number of back-off slots in consideration of the number of hops.
  • the value of k is increased when priority is given to the number of slots of the back-off value by RSSI, and the value of k is decreased in the opposite case.
  • FIG. 4 is an explanatory diagram showing a setting example of the back-off time of each multi-hop wireless device in the multi-hop wireless system according to the first embodiment of the present invention.
  • FIG. 4 as in FIG. 2, a case will be described in which six terminals from terminal 1 to terminal 6 are arranged in a straight line to perform multi-hop transfer, and each terminal can communicate only with an adjacent terminal. I will do it.
  • the relay terminal In the flow for performing multi-hop transfer, the relay terminal cannot receive data to be transferred next during data transfer. Therefore, it is necessary for the relay terminal to complete the data transfer early and arrive at the next data. Therefore, it is desirable to make the data transfer rate larger than the arrival rate.
  • the transfer rate is a rate of passing data to the next relay terminal
  • the arrival rate is a rate of receiving data from the previous relay terminal. That is, the arrival rate is the same as the rate at which data is transferred from the previous relay terminal to its own relay terminal, and corresponds to the transfer rate of the previous relay terminal. Therefore, the transfer rate is determined by the own relay terminal, and the arrival rate is determined by the previous relay terminal.
  • the transfer rate and arrival rate are defined as events at the same relay terminal.
  • the transfer rate and arrival rate are changed by controlling the time of the entire data frame.
  • the data frame is composed of carrier sense, back-off, and data transfer times, and the transmission control unit 400 in FIG. 1 controls the back-off time to change the transfer rate and arrival rate.
  • Carrier sense time requires a fixed time and is not subject to change.
  • the back-off time is reduced.
  • the back-off time is increased. Therefore, the relay terminal on the transmission source (generating terminal) side sets the back-off time relatively large, and the relay terminal on the transmission destination (target terminal) side sets the back-off time relatively small.
  • each relay terminal in the multi-hop transfer flow uses a random value selected from 0 to CWmax as a back-off value. Therefore, in the relay terminal, a case where the transfer rate is larger or smaller than the arrival rate occurs with a similar probability. When the transfer rate is smaller than the arrival rate, data that attempts to arrive is retransmitted or discarded, so that the data arrival rate decreases.
  • Example 1 the relay terminal in the flow of multi-hop transfer has a lower back-off value as it goes from the transmission source (generating terminal) to the transmission destination (target terminal), and a random value is selected from a relatively small range. The Therefore, in the relay terminal, the probability that the transfer rate is higher than the arrival rate is relatively higher than that of the prior art method. Therefore, the data arrival rate is improved as compared with the conventional method.
  • the relay terminal in the flow of multi-hop transfer has a random value from the selection range in which the upper limit value and the lower limit value of the back-off value are decreased from the transmission source (generation terminal) toward the transmission destination (target terminal). Selected. Therefore, in the relay terminal, the probability that the transfer rate is larger than the arrival rate is further increased. Therefore, the data arrival rate is improved as compared with the conventional method.
  • Example 1 and Example 2 are set when the traffic is high.
  • the control of Example 1 is effective when the traffic is relatively low
  • the control of Example 2 is effective when the traffic is relatively high.
  • the case where the traffic is low means that the amount of data handled in the multi-hop section is small, there is no load on each relay terminal, and so-called data can be transferred at any time.
  • the traffic is high the amount of data handled in the multi-hop section is large, and the load on each relay terminal is high. In other words, the transfer of the next relay terminal is not completed even if data transfer is desired. Therefore, it means that the data transfer is delayed in the multi-hop section when it is not in the receiving state and as an extreme case.
  • the multi-hop wireless device of the first embodiment when the channel for transmitting data is idle, the data is transmitted after waiting for the set backoff time, and other devices A transmission / reception processing unit that transmits and receives data in multihop transfer between the device and a transmission control unit that sets back-off time to be smaller as data transmission is performed to a device having a smaller number of multihop transfers among other devices. Since the same transfer procedure (relay method) is used for a plurality of multi-hop transfer flows, the data arrival rate in each multi-hop transfer flow can be improved.
  • the transmission control unit is configured to perform control, and the transmission control unit sets the back-off time to be smaller as the number of retransmissions by the retransmission control unit is smaller, so the data arrival rate in each multi-hop transfer flow Can be improved according to
  • the transmission control unit sets the back-off time to be smaller as the received signal strength of the data is larger, so that the finer back-off considering the radio wave propagation situation Time can be set.
  • the transmission control unit sets the upper limit value of the back-off time to be smaller as the data transmission to the apparatus has a smaller number of multihop transfers.
  • effective control can be realized when the traffic is relatively low.
  • the transmission control unit sets the upper limit value and the lower limit value of the back-off time to be smaller as data transmission is performed to the device having a smaller number of multi-hop transfers. Therefore, effective control can be realized when the traffic is relatively high.
  • any component of the embodiment can be modified or any component of the embodiment can be omitted within the scope of the invention.
  • the multihop radio apparatus and multihop radio system relate to a configuration for controlling the backoff time of a relay terminal in a flow of radio multihop transfer, and an apparatus that performs radio packet communication Suitable for use in.

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Abstract

A transmission/reception processing unit (100) that sends data after waiting a set back-off time, if a channel that transmits data is empty, and sends and receives during data multi-drop transfer, between other devices. A transmission control unit (400) sets shorter back-off times for data transmission to devices having fewer multi-hop transfers than other devices.

Description

マルチホップ無線装置及びマルチホップ無線システムMultihop radio apparatus and multihop radio system
　この発明は、無線マルチホップ転送のフロー内における中継端末のバックオフ時間の制御を行うマルチホップ無線装置及びマルチホップ無線システムに関するものである。 The present invention relates to a multihop radio apparatus and a multihop radio system that control a backoff time of a relay terminal in a flow of radio multihop transfer.
　無線マルチホップ転送に関する従来技術として、例えば非特許文献１に示す方法があった。非特許文献１における無線パケット通信は、無線ＬＡＮを初めとする様々なシステムで採用されている通信形態であり、無線ＬＡＮの規格については、ＩＥＥＥ８０２．１１委員会で標準化が進められている。通信モードの一つにインフラストラクチャモードがあり、ＡＰ（アクセスポイント）に無線端末が無線接続して形成される無線ネットワークを構成している。この非特許文献１に示される方法は、ＡＰ（アクセスポイント）と端末間での通信制御に関する方法である。 As a conventional technique related to wireless multi-hop transfer, for example, there is a method shown in Non-Patent Document 1. The wireless packet communication in Non-Patent Document 1 is a communication form adopted in various systems including a wireless LAN, and standardization of the wireless LAN standard is being promoted by the IEEE 802.11 committee. One of the communication modes is an infrastructure mode, which forms a wireless network formed by wirelessly connecting wireless terminals to an AP (access point). The method disclosed in Non-Patent Document 1 is a method related to communication control between an AP (access point) and a terminal.
　また、これ以外の従来技術として、例えば非特許文献２に示す方法があった。この非特許文献２に示される方法は、音声や映像のようなリアルタイムトラヒックを高い品質で伝送するために、優先制御を導入している。この優先制御では、ＡＰ（アクセスポイント）に入力されたトラヒックを音声、映像、非リアルタイムトラヒックといったカテゴリに分け、それらに対応するキューに格納する。それぞれのキューには優先順位が設定されており、音声や映像のトラヒックが優先的に送信されるように送信制御が行われる方法である。 In addition, as another conventional technique, for example, there is a method shown in Non-Patent Document 2. The method disclosed in Non-Patent Document 2 introduces priority control in order to transmit real-time traffic such as voice and video with high quality. In this priority control, traffic input to an AP (access point) is divided into categories such as voice, video, and non-real-time traffic, and stored in a queue corresponding to them. Priorities are set for each queue, and transmission control is performed so that audio and video traffic is transmitted with priority.
　さらに、無線マルチホップ転送を行う従来装置として、例えば特許文献１に示す装置があった。この特許文献１には、映像、音声等のリアルトラヒックが要求されるフローをマルチホップ転送する際に、他のマルチホップ転送のフローよりもキャリアセンスを優先して行う無線基地局及びマルチホップ制御方法が示されている。 Furthermore, as a conventional device that performs wireless multi-hop transfer, for example, there is a device disclosed in Patent Document 1. This Patent Document 1 discloses a radio base station and multi-hop control in which carrier sense is given priority over other multi-hop transfer flows when multi-hop transfer is performed for flows that require real traffic such as video and audio. The method is shown.
特開２００７－３３５９４３号公報JP 2007-335943 A
　しかしながら、非特許文献１に示された方法では、データフレームのマルチホップ転送のフロー内における転送手順（中継方法）については規定されていない。また、非特許文献２に示された方法は、データの種類に応じた優先制御に関する方法があるが、非特許文献１と同様に、ＡＰ（アクセスポイント）と端末間での通信制御に関する方法であり、データフレームのマルチホップ転送のフロー内における転送手順（中継方法）については規定されていない。 However, in the method disclosed in Non-Patent Document 1, the transfer procedure (relay method) in the flow of multihop transfer of data frames is not defined. The method disclosed in Non-Patent Document 2 is a method related to priority control according to the type of data. Like Non-Patent Document 1, it is a method related to communication control between an AP (access point) and a terminal. Yes, the transfer procedure (relay method) in the flow of multi-hop transfer of data frames is not defined.
　さらに、特許文献１に示された装置では、マルチホップ転送回数の多い特定のマルチホップ転送のフローを優先するために、他のマルチホップ転送のフローとはキャリアセンス時間を差別化して優先しており、そのために他のマルチホップ転送のフローの転送効率が低下するという課題があった。また、マルチホップ転送のフロー内における転送手順（中継方法）については規定されていなかった。 Furthermore, in the apparatus disclosed in Patent Document 1, in order to prioritize a specific multi-hop transfer flow with a large number of multi-hop transfers, the carrier sense time is differentiated and prioritized from other multi-hop transfer flows. Therefore, there has been a problem that the transfer efficiency of other multi-hop transfer flows is reduced. Further, the transfer procedure (relay method) in the flow of multi-hop transfer has not been defined.
　この発明は、上記のような問題点を解決するためになされたものであり、マルチホップ転送のフロー内の転送効率を向上させることのできるマルチホップ無線装置及びマルチホップ無線システムを得ることを目的としている。 The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a multi-hop radio apparatus and a multi-hop radio system that can improve transfer efficiency in a multi-hop transfer flow. It is said.
　この発明に係るマルチホップ無線装置は、データを送信するチャネルが空き状態であった場合は設定されたバックオフ時間待機した後にデータを送信すると共に、他の装置との間でデータのマルチホップ転送における送受信を行う送受信処理部と、他の装置のうち、マルチホップ転送の回数が少ない装置へのデータ送信であるほど、バックオフ時間を少なく設定する送信制御部とを備えたものである。 The multi-hop wireless device according to the present invention transmits data after waiting for a set back-off time when a channel for transmitting data is idle, and multi-hop transfer of data with other devices A transmission / reception processing unit that performs transmission / reception in the network and a transmission control unit that sets the back-off time to be smaller as data transmission is performed to a device that has a smaller number of multi-hop transfers among other devices.
　この発明のマルチホップ無線装置は、マルチホップ転送の回数が少ない装置へのデータ送信であるほど、バックオフ時間を少なく設定するようにしたものである。これにより、それぞれのマルチホップ転送のフロー内のデータ到達率を向上させることができる。 In the multi-hop wireless device of the present invention, the back-off time is set to be smaller as the data transmission to the device having a smaller number of multi-hop transfers is performed. Thereby, the data arrival rate in the flow of each multihop transfer can be improved.
この発明の実施の形態１によるマルチホップ無線装置を示す構成図である。It is a block diagram which shows the multihop radio | wireless apparatus by Embodiment 1 of this invention. この発明の実施の形態１のマルチホップ無線システムにおける各マルチホップ無線装置のルーティングテーブルの説明図である。It is explanatory drawing of the routing table of each multihop radio | wireless apparatus in the multihop radio | wireless system of Embodiment 1 of this invention. この発明の実施の形態１によるマルチホップ無線装置のバックオフ時間の算出方法の説明図である。It is explanatory drawing of the calculation method of the back-off time of the multihop radio | wireless apparatus by Embodiment 1 of this invention. この発明の実施の形態１のマルチホップ無線システムにおける各マルチホップ無線装置のバックオフ時間の設定例を示す説明図である。It is explanatory drawing which shows the example of a setting of the back-off time of each multihop radio | wireless apparatus in the multihop radio | wireless system of Embodiment 1 of this invention.
実施の形態１．
　図１は、この発明の実施の形態１によるマルチホップ無線装置を示す構成図である。
　マルチホップ無線装置は、図示のように、送受信処理部１００、送信バッファ部２００、パケット生成部２１０、ヘッダ除去部３００、データ処理部３１０、送信制御部４００、ルーティングテーブル管理部４１０、再送制御部４２０を備えている。送受信処理部１００は、変調部１１０、送信部１２０、アンテナ１３０、受信部１４０、復調部１５０、キャリア検出部１６０を備えており、他の端末とのデータの送受信を行う処理部である。 Embodiment 1 FIG.
FIG. 1 is a block diagram showing a multihop radio apparatus according to Embodiment 1 of the present invention.
As shown in the figure, the multihop radio apparatus includes a transmission / reception processing unit 100, a transmission buffer unit 200, a packet generation unit 210, a header removal unit 300, a data processing unit 310, a transmission control unit 400, a routing table management unit 410, and a retransmission control unit. 420 is provided. The transmission / reception processing unit 100 includes a modulation unit 110, a transmission unit 120, an antenna 130, a reception unit 140, a demodulation unit 150, and a carrier detection unit 160, and is a processing unit that performs transmission / reception of data with other terminals.
　送受信処理部１００には、アンテナ１３０を介して受信された無線信号が入力される。
　受信部１４０は、入力した無線信号に対して周波数変換、フィルタリング、直交検波及びＡＤ（Ａｎａｌｏｇ　ｔｏ　Ｄｉｇｉｔａｌ）変換を含む受信処理を施している。アンテナ１３０が送信状態以外の時には、受信部１４０には常に無線伝搬路上の無線信号が入力されて、無線信号の所定の周波数チャネルにおける受信信号の強度を表すＲＳＳＩ（Ｒｅｃｅｉｖｅｄ　Ｓｉｇｎａｌ　Ｓｔｒｅｎｇｔｈ　Ｉｎｄｉｃａｔｏｒ）信号がキャリア検出部１６０へ出力される。また、受信部１４０が無線信号を受信した場合には、受信処理されたベースバンド信号が復調部１５０へ出力される。 The radio signal received via the antenna 130 is input to the transmission / reception processing unit 100.
The receiving unit 140 performs reception processing including frequency conversion, filtering, quadrature detection, and AD (Analog to Digital) conversion on the input radio signal. When the antenna 130 is not in the transmission state, a radio signal on the radio propagation path is always input to the receiving unit 140, and an RSSI (Received Signal Strength Indicator) signal representing the strength of the received signal in a predetermined frequency channel of the radio signal is a carrier. It is output to the detection unit 160. Further, when the reception unit 140 receives a radio signal, the baseband signal subjected to reception processing is output to the demodulation unit 150.
　キャリア検出部１６０は、受信部１４０から入力したＲＳＳＩ信号を用いて所定の周波数チャネルの状態を判定する。一定期間に渡ってＲＳＳＩ信号が予め定めた閾値以下の場合には周波数チャネルは空き状態と判定し、また、閾値以上の場合には周波数チャネルはビジー状態であると判定する。この判定結果は送信制御部４００へキャリアセンス結果として通知される。 The carrier detection unit 160 determines the state of a predetermined frequency channel using the RSSI signal input from the reception unit 140. When the RSSI signal is below a predetermined threshold over a certain period, it is determined that the frequency channel is idle, and when it is above the threshold, it is determined that the frequency channel is busy. This determination result is notified to the transmission control unit 400 as a carrier sense result.
　復調部１５０は、受信部１４０で受信処理を施されたベースバンド信号に対して復調処理を行い、受信パケットとしてヘッダ除去部３００へ出力する。ヘッダ除去部３００では、受信パケットのヘッダに含まれる制御情報を解析し、宛先アドレスが自端末のアドレスと一致しない場合には受信パケットを破棄し、一致する場合にはヘッダを除去してデータフレームを抽出し、データ処理部３１０へ出力する。 Demodulation section 150 performs demodulation processing on the baseband signal that has been subjected to reception processing by reception section 140, and outputs the result to header removal section 300 as a received packet. The header removal unit 300 analyzes the control information included in the header of the received packet, discards the received packet if the destination address does not match the address of the own terminal, and removes the header if the destination address matches, and removes the data frame Is extracted and output to the data processing unit 310.
　データ処理部３１０では、ヘッダ除去部３００からのデータフレームに対して、通常のデータに関しては自端末に接続されるコンピュータ等の装置へ受信データとして出力する。
　また、ハローパケットのようなネットワーク情報に関するデータに関しては、ルーティングテーブル管理部４１０へ出力する。さらに、送信データに対するＡＣＫ（ＡＣＫｎｏｗｌｅｄｇｅ）信号に関しては、再送制御部４２０へ出力する。 The data processing unit 310 outputs normal data as received data to a device such as a computer connected to the terminal with respect to the data frame from the header removal unit 300.
Further, data relating to network information such as a hello packet is output to the routing table management unit 410. Further, an ACK (ACKnowledge) signal for transmission data is output to retransmission control section 420.
　ルーティングテーブル管理部４１０では、自端末と周辺端末との無線ネットワーク関係の情報を管理しており、例えば、直接送受信可能な端末や、マルチホップ転送されて送受信可能な端末とそのマルチホップ転送回数や、ハローパケットを受信した際のＲＳＳＩ情報等をルーティングテーブルで表している。なお、ルーティングテーブルの詳細については図２を用いて後述する。 The routing table management unit 410 manages wireless network-related information between its own terminal and peripheral terminals. For example, a terminal that can be directly transmitted / received, a terminal that can be transmitted / received by multi-hop transfer, and the number of multi-hop transfers, The RSSI information and the like when the hello packet is received are represented by a routing table. Details of the routing table will be described later with reference to FIG.
　送信バッファ部２００は、自端末に接続されるコンピュータ等の装置から送信データが入力されると、送信制御部４００に対してデータフレームの入力を通知し、データフレームに関する情報（データフレーム数、データサイズ、送信元（発生端末）、送信先（目的端末）のアドレス等）を送信制御部４００へ逐次出力する。 When transmission data is input from a device such as a computer connected to its own terminal, the transmission buffer unit 200 notifies the transmission control unit 400 of the input of a data frame, and information about the data frame (number of data frames, data Size, transmission source (generating terminal), transmission destination (target terminal) address, etc.) are sequentially output to the transmission control unit 400.
　再送制御部４２０では、送信バッファ部２００からパケット生成部２１０へ出力された送信データに関する情報（データフレーム数、データサイズ、シーケンス番号、送信元（発生端末）、送信先（目的端末）のアドレス等）及び時刻と、データ処理部３１０からのＡＣＫ信号に関する情報（ＡＣＫ識別ヘッダ、送信元（発生端末）のアドレス等）及び時刻とから、送信データが受信されたかを判定し、結果を送信制御部４００へ通知する。
　既定の時間内にＡＣＫ信号が届いた場合には、送信データは受信が成功したものとして、送信制御部４００へ通知する。一方、既定の時間内にＡＣＫ信号が届かない場合には、送信データは受信が失敗したものとして、送信制御部４００へ通知する。 In retransmission control section 420, information on transmission data output from transmission buffer section 200 to packet generation section 210 (number of data frames, data size, sequence number, transmission source (generating terminal), transmission destination (target terminal) address, etc. ) And time, information on the ACK signal from the data processing unit 310 (ACK identification header, address of transmission source (generating terminal), etc.), and time, it is determined whether transmission data is received, and the result is transmitted to the transmission control unit. 400 is notified.
If the ACK signal arrives within the predetermined time, the transmission data is notified to the transmission control unit 400 as having been successfully received. On the other hand, if the ACK signal does not reach within the predetermined time, the transmission data is notified to the transmission control unit 400 as reception failure.
　送信制御部４００は、送信バッファ部２００からのデータフレームに関する情報と、キャリア検出部１６０からのキャリアセンス結果に基づいて、送信制御処理を開始可能であるか判定する。送信バッファ部２００にデータフレームが入力されて、周波数チャネルが空き状態の場合には、送信制御処理を開始する。また、それ以外の場合には、送信制御処理を開始しない。 The transmission control unit 400 determines whether the transmission control process can be started based on the information regarding the data frame from the transmission buffer unit 200 and the carrier sense result from the carrier detection unit 160. When a data frame is input to the transmission buffer unit 200 and the frequency channel is empty, transmission control processing is started. In other cases, the transmission control process is not started.
　送信制御部４００における送信制御処理では、送信元（発生端末）から送信先（目的端末）へデータを送る際に、ルーティングテーブル管理部４１０のルーティングテーブルからマルチホップ転送回数、直接転送可能な隣接端末アドレスとＲＳＳＩ情報を取得し、バックオフのためのスロット数を割り当てる。バックオフ時間はこのスロット数とスロット時間（通常はシンボル時間）の掛け算で表される。このバックオフ時間は、マルチホップ転送回数が比較的多い送信元（発生端末）側の中継端末（送信元側の装置）ほど比較的大きな値を設定し、送信先（目的端末）側のマルチホップ転送回数が比較的少ない中継端末（送信先側の装置）ほど比較的小さな値を設定する。従って、送信先（目的端末）側の中継端末ほど、単位時間当たりのデータ転送量を大きく設定して優先する。 In the transmission control process in the transmission control unit 400, when sending data from the transmission source (generating terminal) to the transmission destination (target terminal), the number of multihop transfers and the adjacent terminals that can be directly transferred from the routing table of the routing table management unit 410 The address and RSSI information are acquired, and the number of slots for backoff is assigned. The back-off time is expressed by multiplying the number of slots and the slot time (usually symbol time). This back-off time is set to a relatively large value for a relay terminal (device on the transmission source side) on the transmission source (source terminal) side with a relatively large number of multi-hop transfers, and the multi-hop on the transmission destination (target terminal) side. A relatively small value is set for a relay terminal (device on the transmission destination side) having a relatively small number of transfers. Therefore, a relay terminal on the transmission destination (target terminal) side gives priority to a larger data transfer amount per unit time.
　また、このバックオフ時間に直接転送可能な隣接端末のＲＳＳＩ情報を追加しても良い。
　具体的には、ＲＳＳＩが比較的大きく電波伝搬状況が良い場合には比較的小さな値を設定し、ＲＳＳＩが比較的小さく電波伝搬状況が良くない場合には比較的大きな値を設定する。ＲＳＳＩが比較的小さな電波伝搬状況が良くない場合にはパケットの到達率が低下するのでこの区間の優先度を低下させ、トラヒックを軽減させて比較的強い負荷を掛けないよう配慮する。一方、ＲＳＳＩが比較的大きく電波伝搬状況が良い場合はパケットの到達率が向上することから、その区間の優先度を高くしてよりトラヒックを高くして比較的強い負荷をかけるようにする。このようにして、マルチホップ転送回数に基づくバックオフ時間とＲＳＳＩに基づくバックオフ時間を組み合わせてバックオフ時間を設定する。これにより、電波伝搬状況も考慮したよりきめ細かい設定を行うことができる。 Further, RSSI information of an adjacent terminal that can be directly transferred during the back-off time may be added.
Specifically, a relatively small value is set when the RSSI is relatively large and the radio wave propagation situation is good, and a relatively large value is set when the RSSI is relatively small and the radio wave propagation situation is not good. When the radio wave propagation situation with a relatively small RSSI is not good, the packet arrival rate is lowered. Therefore, the priority of this section is lowered, so that traffic is reduced and a relatively strong load is not applied. On the other hand, when the RSSI is relatively large and the radio wave propagation state is good, the packet arrival rate is improved. Therefore, the priority of the section is increased to increase the traffic and apply a relatively strong load. In this way, the back-off time is set by combining the back-off time based on the number of multi-hop transfers and the back-off time based on RSSI. As a result, finer settings can be made in consideration of radio wave propagation conditions.
　また、再送制御部４２０が、送受信処理部１００の送信データに対する送信先装置での受信が失敗したと判定した場合には、送信データに対して同じシーケンス番号で再送を行う。受信失敗の回数が増えて、一定時間における再送回数が増えてきた場合には、バックオフのためにスロット数を増やしてバックオフ時間全体を増やす。また、受信失敗の回数が減って、一定時間における再送回数が減ってきた場合には、バックオフのためにスロット数を減らしてバックオフ時間全体を減らす。このようにして、再送状況からバックオフ時間全体の範囲を変化させることにより、トラヒック状況に応じた最大のスループットを得ることができるようになる。 Further, when the retransmission control unit 420 determines that reception of the transmission data of the transmission / reception processing unit 100 by the transmission destination device has failed, the retransmission control unit 420 retransmits the transmission data with the same sequence number. When the number of reception failures increases and the number of retransmissions in a certain time increases, the number of slots is increased for backoff to increase the entire backoff time. In addition, when the number of reception failures decreases and the number of retransmissions in a certain time decreases, the number of slots is reduced for backoff to reduce the entire backoff time. In this way, the maximum throughput according to the traffic situation can be obtained by changing the entire range of the back-off time from the retransmission situation.
　送信制御部４００では、送信制御処理によって設定されたバックオフ時間がカウントダウンされて零となった時点で、送信バッファ部２００の先頭に蓄積されたデータフレームをパケット生成部２１０へ出力する。また、カウントダウンの途中で、キャリア検出部１６０からＲＳＳＩ情報が閾値以上となった場合には周波数チャネルはビジー状態であると判定し、カウントダウンをいったん停止する。その後、ＲＳＳＩ情報が閾値以下となった場合には周波数チャネルは空き状態と判定し、再びカウントダウンを開始する。 The transmission control unit 400 outputs the data frame accumulated at the head of the transmission buffer unit 200 to the packet generation unit 210 when the back-off time set by the transmission control process is counted down to zero. If the RSSI information is equal to or greater than the threshold value from the carrier detection unit 160 during the countdown, the frequency channel is determined to be busy, and the countdown is temporarily stopped. Thereafter, when the RSSI information becomes equal to or less than the threshold value, it is determined that the frequency channel is in an empty state, and countdown is started again.
　パケット生成部２１０は、送信バッファ部２００からのデータフレームに対して、送信制御部４００からルーティングテーブル管理部４１０のルーティングテーブルの情報を得て、送信先（目的端末）のアドレス、送信元（発生端末）アドレス、マルチホップ転送時には直接送受信可能な隣接端末のアドレス等の制御情報で構成されるヘッダ及び誤り検出符号を付加して無線パケットを生成する。生成された無線パケットは、変調部１１０で変調処理を施され、送信部１２０でＤＡ（Ｄｉｇｉｔａｌ　ｔｏ　Ａｎａｌｏｇ）変換、周波数変換、フィルタリング及び電力増幅を含む送信処理が施され、アンテナ１３０から無線信号として送信される。 For the data frame from the transmission buffer unit 200, the packet generation unit 210 obtains the routing table information of the routing table management unit 410 from the transmission control unit 400, and transmits the destination (target terminal) address and transmission source (occurrence). A wireless packet is generated by adding a header and an error detection code composed of control information such as a terminal) address and an address of an adjacent terminal that can be directly transmitted and received during multi-hop transmission. The generated wireless packet is subjected to modulation processing by the modulation unit 110, and subjected to transmission processing including DA (Digital to Analog) conversion, frequency conversion, filtering, and power amplification by the transmission unit 120. Sent.
　図２は本発明の実施の形態１のマルチホップ無線システムにおける各マルチホップ無線装置のルーティングテーブルの説明図である。一例として、端末１から端末６までの６台の端末を直線状に配置して、マルチホップ転送する場合について説明する。また、各端末は隣の端末とのみ通信が可能であることとする。 FIG. 2 is an explanatory diagram of a routing table of each multi-hop wireless device in the multi-hop wireless system according to the first embodiment of the present invention. As an example, a case will be described in which six terminals from the terminal 1 to the terminal 6 are arranged in a straight line to perform multihop transfer. In addition, each terminal can communicate only with an adjacent terminal.
　各端末のルーティングテーブルには、自端末を示すｏｒｉｇｉｎａｌ（ｏｒｇ）、隣接端末を示すｇａｔｅｗａｙ（ｇｗ）、送信元（発生端末）や送信先（目的端末）を示すｄｅｓｔｉｎａｔｉｏｎ（ｄｓｔ）、その際のマルチホップ数を示すｈｏｐ、隣接端末からのハローパケット受信時のＲＳＳＩ情報（ｒｓｓｉ）が管理されている。また、データフレーム（図示省略）には、データの発生元である送信元（発生端末）を示すｓｏｕｒｃｅ、送信先（目的端末）を示すｄｅｓｔｉｎａｔｉｏｎの情報が収納されている。従って、送信元（発生端末）で発生したデータは、各端末が自己のルーティングテーブルにより、隣接端末を中継して送信先端末（目的端末）までマルチホップ転送される。 The routing table of each terminal includes an original (org) indicating its own terminal, a gateway (gw) indicating an adjacent terminal, a destination (dst) indicating a transmission source (generating terminal) and a transmission destination (target terminal), and a multipoint at that time A hop indicating the number of hops and RSSI information (rssi) when a hello packet is received from an adjacent terminal are managed. In addition, a data frame (not shown) stores information indicating a source (source terminal) that is a source of data and destination indicating a destination (target terminal). Therefore, the data generated at the transmission source (generation terminal) is multi-hop transferred by each terminal to the transmission destination terminal (target terminal) by relaying the adjacent terminal according to its own routing table.
　具体的には、送信元端末１から送信先端末６へデータをマルチホップ転送する場合には、まず、端末１は自己のルーティングテーブルにより隣接端末２へデータを転送すれば、５ホップで送信先端末６へデータを届けることができる。次に、端末２は自己のルーティングテーブルにより隣接端末３へデータを転送すれば、４ホップで送信先端末６へデータを届けることができる。同じく、端末３は自己のルーティングテーブルにより隣接端末４へデータを転送すれば、３ホップで送信先端末６へデータを届けることができる。同様に、端末４は自己のルーティングテーブルにより隣接端末５へデータを転送すれば、２ホップで送信先端末６へデータを届けることができる。最後に、端末５は自己のルーティングテーブルにより送信先端末６が隣接端末であり１ホップでデータを届けることができる。このような一連の関係から、送信元端末１は送信先端末６へ中継端末を経由してマルチホップ転送によりデータを届けることができる。 Specifically, when data is transferred from the source terminal 1 to the destination terminal 6 in a multi-hop manner, first, if the terminal 1 transfers data to the adjacent terminal 2 using its own routing table, the destination is transmitted in five hops. Data can be delivered to the terminal 6. Next, if the terminal 2 transfers the data to the adjacent terminal 3 by using its own routing table, the data can be delivered to the destination terminal 6 in 4 hops. Similarly, if the terminal 3 transfers the data to the adjacent terminal 4 by using its own routing table, the data can be delivered to the destination terminal 6 with three hops. Similarly, if the terminal 4 transfers data to the adjacent terminal 5 using its own routing table, it can deliver the data to the destination terminal 6 in two hops. Finally, the terminal 5 can deliver data in one hop because the destination terminal 6 is an adjacent terminal according to its own routing table. From such a series of relationships, the transmission source terminal 1 can deliver data to the transmission destination terminal 6 by multihop transfer via the relay terminal.
　図３は本発明の実施の形態１によるバックオフ時間の算出方法を示す説明図である。
　バックオフ時間はホップ数を考慮した値とＲＳＳＩを考慮した値の合計として算出される。バックオフのスロット数の最大値：ＣＷ（Ｃｏｎｔｅｎｔｉｏｎ　Ｗｉｎｄｏｗ）ｍａｘは、従来技術の非特許文献１と同じく１０２３としても良い。また、周辺端末の台数に較べて十分余裕のある値を設定しても良い。 FIG. 3 is an explanatory diagram showing a backoff time calculation method according to Embodiment 1 of the present invention.
The back-off time is calculated as the sum of a value considering the number of hops and a value considering RSSI. The maximum value of the number of back-off slots: CW (Contention Window) max may be set to 1023 as in the non-patent document 1 of the prior art. Further, a value having a sufficient margin as compared with the number of peripheral terminals may be set.
　また、再送制御部４２０からの受信失敗通知の回数が増えて、一定時間における再送回数が増えてきた場合には、トラヒックが高い状態であると判断して低い状態にするために、バックオフのスロット数の最大値：ＣＷｍａｘ値を１０２３よりも大きな値とする。また、再送制御部４２０からの受信失敗通知の回数が減って、一定時間における再送回数が減ってきた場合には、トラヒックが低い状態であると判断して高い状態にするために、バックオフのスロット数の最大値：ＣＷｍａｘ値を１０２３よりも小さな値とする。 In addition, when the number of reception failure notifications from the retransmission control unit 420 increases and the number of retransmissions in a certain time increases, it is determined that the traffic is in a high state and the back-off state is set. Maximum value of the number of slots: The CWmax value is set to a value larger than 1023. In addition, when the number of reception failure notifications from the retransmission control unit 420 decreases and the number of retransmissions in a certain time decreases, it is determined that the traffic is in a low state and the backoff state is increased. Maximum number of slots: CWmax value is set to a value smaller than 1023.
　まず、ホップ数を考慮したバックオフ時間を説明する。各中継端末は、送信元（発生端末）で発生したデータについて、自己のルーティングテーブルにより、送信元（発生端末）までのホップ数と送信先（目的端末）までのホップ数の情報を取得し、マルチホップ転送における全ホップ数を把握する。 First, the back-off time considering the number of hops will be explained. Each relay terminal obtains information on the number of hops to the transmission source (generating terminal) and the number of hops to the transmission destination (target terminal) by using its own routing table for the data generated at the transmission source (generating terminal), Know the total number of hops in a multi-hop transfer.
　例１の中継端末は、ＣＷ（Ｃｏｎｔｅｎｔｉｏｎ　Ｗｉｎｄｏｗ）ｍａｘに、０から｛（送信先（目的端末）までのホップ（ｈｏｐ）数）／（全ホップ（ｈｏｐ）数）｝を乗算した範囲からランダムな値を選択する。 The relay terminal of Example 1 is random from a range obtained by multiplying CW (Contention Window) max by 0 to {(the number of hops to the destination (target terminal)) / (the number of all hops)}. Select a value.
　例２の中継端末は、ＣＷ（Ｃｏｎｔｅｎｔｉｏｎ　Ｗｉｎｄｏｗ）ｍａｘに、｛（送信先（目的端末）までのホップ数－１）／全ホップ数｝から｛送信先（目的端末）までのホップ数／全ホップ数｝を乗算した範囲からランダムな値を選択する。 The relay terminal of Example 2 sets the CW (Contention Window) max to {number of hops to the destination (target terminal) −1) / number of all hops} to {number of hops from the destination (target terminal) / all hops] A random value is selected from the range multiplied by the number}.
　そして、ＲＳＳＩを考慮したバックオッフのスロット数との重み付け具合から、任意の係数：Ｓで除算される。ホップ数によるバックオフ値のスロット数を優先する場合にはＳの値を小さくし、逆の場合にはＳの値を大きくする。 Then, it is divided by an arbitrary coefficient: S from the weighting degree with the number of back-off slots in consideration of RSSI. When priority is given to the number of slots of the back-off value based on the number of hops, the value of S is decreased, and in the opposite case, the value of S is increased.
　次に、ＲＳＳＩを考慮したバックオフ時間を説明する。各中継端末は、自己のルーティングテーブルにより、隣接端末とのＲＳＳＩ情報を取得し、任意の係数：－ｋを乗算する。
　ＲＳＳＩが比較的大きく電波伝搬状況が良い場合、例えばＲＳＳＩ＝－３０ｄＢｍの場合には３０ｋの値が設定され、ＲＳＳＩが比較的小さく電波伝搬状況が悪い場合、例えばＲＳＳＩ＝－９０ｄＢｍの場合には９０ｋの値が設定される。これにより、電波伝搬状況が良い場合にはバックオフ時間が比較的小さな値が選択されて優先度を高くする。 Next, the back-off time considering RSSI will be described. Each relay terminal acquires RSSI information with an adjacent terminal from its own routing table and multiplies an arbitrary coefficient: -k.
When the RSSI is relatively large and the radio wave propagation situation is good, for example, a value of 30k is set when the RSSI = −30 dBm, and when the RSSI is relatively small and the radio wave propagation situation is bad, for example, when the RSSI = −90 dBm, it is 90k. The value of is set. Thereby, when the radio wave propagation state is good, a value with a relatively small back-off time is selected to increase the priority.
　そして、ホップ数を考慮したバックオッフのスロット数との重み付け具合から、任意の係数：ｋで乗算される。ＲＳＳＩによるバックオフ値のスロット数を優先する場合にはｋの値を大きくし、逆の場合にはｋの値を小さくする。 Then, it is multiplied by an arbitrary coefficient: k from the weighting degree with the number of back-off slots in consideration of the number of hops. The value of k is increased when priority is given to the number of slots of the back-off value by RSSI, and the value of k is decreased in the opposite case.
　図４は本発明の実施の形態１のマルチホップ無線システムにおける各マルチホップ無線装置のバックオフ時間の設定例を示す説明図である。図４では、図２と同じく、端末１から端末６までの６台の端末を直線状に配置して、マルチホップ転送する場合について説明し、各端末は隣の端末とのみ通信が可能であることとする。 FIG. 4 is an explanatory diagram showing a setting example of the back-off time of each multi-hop wireless device in the multi-hop wireless system according to the first embodiment of the present invention. In FIG. 4, as in FIG. 2, a case will be described in which six terminals from terminal 1 to terminal 6 are arranged in a straight line to perform multi-hop transfer, and each terminal can communicate only with an adjacent terminal. I will do it.
　マルチホップ転送を行うフロー内において、中継端末はデータ転送中には、次に転送するデータを受け取ることができない。従って、中継端末はデータ転送を早く完了させて、次のデータを到着させる必要がある。そこで、データの転送率を到着率よりも大きくすることが望ましい。ここで、転送率とは次の中継端末へデータを渡す割合であり、到着率とは前の中継端末からデータを受け取る割合である。すなわち、到着率は、前の中継端末から自身の中継端末へデータを渡す割合と同じで、前の中継端末の転送率に相当する。従って、転送率は自中継端末で決定し、到着率は前の中継端末によって決定されることになる。
　なお、転送率も到着率も同一中継端末における事象として定義する。 In the flow for performing multi-hop transfer, the relay terminal cannot receive data to be transferred next during data transfer. Therefore, it is necessary for the relay terminal to complete the data transfer early and arrive at the next data. Therefore, it is desirable to make the data transfer rate larger than the arrival rate. Here, the transfer rate is a rate of passing data to the next relay terminal, and the arrival rate is a rate of receiving data from the previous relay terminal. That is, the arrival rate is the same as the rate at which data is transferred from the previous relay terminal to its own relay terminal, and corresponds to the transfer rate of the previous relay terminal. Therefore, the transfer rate is determined by the own relay terminal, and the arrival rate is determined by the previous relay terminal.
The transfer rate and arrival rate are defined as events at the same relay terminal.
　１回のデータフレームで転送できるデータ量は固定なので、それに掛かるデータフレーム全体の時間を制御して転送率や到着率を変化させる。データフレームは、キャリアセンス、バックオフ、データ転送の時間で構成され、図１における送信制御部４００では、バックオフ時間を制御して転送率や到着率を変化させる。キャリアセンスの時間は固定時間が必要であり変化の対象としない。転送率を大きくするためにはバックオフ時間を小さくし、到着率を小さくするためにはバックオフ時間を大きくする。従って、送信元（発生端末）側の中継端末は比較的バックオフ時間を大きくし、送信先（目的端末）側の中継端末は比較的バックオフ時間を小さく設定する。 Since the amount of data that can be transferred in one data frame is fixed, the transfer rate and arrival rate are changed by controlling the time of the entire data frame. The data frame is composed of carrier sense, back-off, and data transfer times, and the transmission control unit 400 in FIG. 1 controls the back-off time to change the transfer rate and arrival rate. Carrier sense time requires a fixed time and is not subject to change. In order to increase the transfer rate, the back-off time is reduced. To reduce the arrival rate, the back-off time is increased. Therefore, the relay terminal on the transmission source (generating terminal) side sets the back-off time relatively large, and the relay terminal on the transmission destination (target terminal) side sets the back-off time relatively small.
　従来技術の非特許文献１による方法では、マルチホップ転送のフロー内の各中継端末は、０からＣＷｍａｘの中から選択されたランダムな値をバックオフ値としている。従って、中継端末では、転送率が到着率よりも大きい場合や小さい場合が同程度の確率で発生する。
　転送率が到着率よりも小さい時には、到着を試みるデータが再送や破棄されるため、データ到着率が低下してしまう。 In the method according to Non-Patent Document 1 of the prior art, each relay terminal in the multi-hop transfer flow uses a random value selected from 0 to CWmax as a back-off value. Therefore, in the relay terminal, a case where the transfer rate is larger or smaller than the arrival rate occurs with a similar probability.
When the transfer rate is smaller than the arrival rate, data that attempts to arrive is retransmitted or discarded, so that the data arrival rate decreases.
　例１では、マルチホップ転送のフロー内の中継端末は、送信元（発生端末）から送信先（目的端末）に向かうほどバックオフ値の上限値が下がり比較的小さな幅からランダムな値が選択される。従って、中継端末においては、転送率が到着率よりも大きくなる確率が従来技術の方法よりも比較的高くなる。よって、従来技術による方法よりもデータ到達率が向上する。 In Example 1, the relay terminal in the flow of multi-hop transfer has a lower back-off value as it goes from the transmission source (generating terminal) to the transmission destination (target terminal), and a random value is selected from a relatively small range. The Therefore, in the relay terminal, the probability that the transfer rate is higher than the arrival rate is relatively higher than that of the prior art method. Therefore, the data arrival rate is improved as compared with the conventional method.
　例２では、マルチホップ転送のフロー内の中継端末は、送信元（発生端末）から送信先（目的端末）に向かうほどバックオフ値の上限値及び下限値が下がった選択幅からランダムな値が選択される。従って、中継端末においては、転送率が到着率よりも大きくなる確率がさらに高くなる。よって、従来技術による方法よりもデータ到達率が向上する。 In Example 2, the relay terminal in the flow of multi-hop transfer has a random value from the selection range in which the upper limit value and the lower limit value of the back-off value are decreased from the transmission source (generation terminal) toward the transmission destination (target terminal). Selected. Therefore, in the relay terminal, the probability that the transfer rate is larger than the arrival rate is further increased. Therefore, the data arrival rate is improved as compared with the conventional method.
　なお、例１及び例２は、トラヒックが高い場合に設定する方式としている。そのなかでも、比較的トラヒックが低い場合には例１の制御を、比較的トラヒックが高い場合には例２の制御が効果的である。ここで、トラヒックが低い場合とは、マルチホップ区間内で扱うデータ量が少ない場合で、各中継端末に負荷が無く、届いたデータを、謂わば、何時でも転送可能な状態を意味する。一方、トラヒックが高い場合とは、マルチホップ区間内で扱うデータ量が多い場合で、各中継端末の負荷が高く、謂わば、データを転送したくとも次の中継端末の転送が完了していないために、受け取る状態になっていない場合で、極端な場合としてはマルチホップ区間内でデータ転送が滞ってしまっているような状態を意味している。 Note that Example 1 and Example 2 are set when the traffic is high. Among them, the control of Example 1 is effective when the traffic is relatively low, and the control of Example 2 is effective when the traffic is relatively high. Here, the case where the traffic is low means that the amount of data handled in the multi-hop section is small, there is no load on each relay terminal, and so-called data can be transferred at any time. On the other hand, when the traffic is high, the amount of data handled in the multi-hop section is large, and the load on each relay terminal is high. In other words, the transfer of the next relay terminal is not completed even if data transfer is desired. Therefore, it means that the data transfer is delayed in the multi-hop section when it is not in the receiving state and as an extreme case.
　以上説明したように、実施の形態１のマルチホップ無線装置によれば、データを送信するチャネルが空き状態であった場合は設定されたバックオフ時間待機した後にデータを送信すると共に、他の装置との間でデータのマルチホップ転送における送受信を行う送受信処理部と、他の装置のうち、マルチホップ転送の回数が少ない装置へのデータ送信であるほど、バックオフ時間を少なく設定する送信制御部とを備えたので、マルチホップ転送の複数のフローに対して同じ転送手順（中継方法）を用い、それぞれのマルチホップ転送のフロー内のデータ到達率を向上させることができる。 As described above, according to the multi-hop wireless device of the first embodiment, when the channel for transmitting data is idle, the data is transmitted after waiting for the set backoff time, and other devices A transmission / reception processing unit that transmits and receives data in multihop transfer between the device and a transmission control unit that sets back-off time to be smaller as data transmission is performed to a device having a smaller number of multihop transfers among other devices. Since the same transfer procedure (relay method) is used for a plurality of multi-hop transfer flows, the data arrival rate in each multi-hop transfer flow can be improved.
　また、実施の形態１のマルチホップ無線装置によれば、送受信処理部が送信するデータを送信先装置が受信に成功したか否かを判定し、受信に失敗したと判定した場合はデータの再送制御を行う再送制御部を備え、送信制御部は、再送制御部による再送回数が少ないほどバックオフ時間を少なく設定するようにしたので、それぞれのマルチホップ転送のフロー内のデータ到達率をトラヒック状況に応じて向上させることができる。 Further, according to the multi-hop wireless device of the first embodiment, it is determined whether the transmission destination device has successfully received the data transmitted by the transmission / reception processing unit. The transmission control unit is configured to perform control, and the transmission control unit sets the back-off time to be smaller as the number of retransmissions by the retransmission control unit is smaller, so the data arrival rate in each multi-hop transfer flow Can be improved according to
　また、実施の形態１のマルチホップ無線装置によれば、送信制御部は、データの受信信号強度が大きいほどバックオフ時間を少なく設定するようにしたので、電波伝搬状況も考慮したよりきめ細かいバックオフ時間の設定を行うことができる。 Also, according to the multi-hop radio apparatus of Embodiment 1, the transmission control unit sets the back-off time to be smaller as the received signal strength of the data is larger, so that the finer back-off considering the radio wave propagation situation Time can be set.
　また、実施の形態１のマルチホップ無線装置によれば、送信制御部は、マルチホップ転送の回数が少ない装置へのデータ送信であるほど、バックオフ時間の上限値を小さく設定するようにしたので、比較的トラヒックが低い場合に有効な制御を実現することができる。 In addition, according to the multihop radio apparatus of the first embodiment, the transmission control unit sets the upper limit value of the back-off time to be smaller as the data transmission to the apparatus has a smaller number of multihop transfers. Thus, effective control can be realized when the traffic is relatively low.
　また、実施の形態１のマルチホップ無線装置によれば、送信制御部は、マルチホップ転送の回数が少ない装置へのデータ送信であるほど、バックオフ時間の上限値及び下限値を小さく設定するようにしたので、比較的トラヒックが高い場合に有効な制御を実現することができる。 In addition, according to the multi-hop wireless device of the first embodiment, the transmission control unit sets the upper limit value and the lower limit value of the back-off time to be smaller as data transmission is performed to the device having a smaller number of multi-hop transfers. Therefore, effective control can be realized when the traffic is relatively high.
　なお、本願発明はその発明の範囲内において、実施の形態の任意の構成要素の変形、もしくは実施の形態の任意の構成要素の省略が可能である。 In the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted within the scope of the invention.
　以上のように、この発明に係るマルチホップ無線装置及びマルチホップ無線システムは、無線マルチホップ転送のフロー内における中継端末のバックオフ時間の制御を行う構成に関するものであり、無線パケット通信を行う装置に用いるのに適している。 As described above, the multihop radio apparatus and multihop radio system according to the present invention relate to a configuration for controlling the backoff time of a relay terminal in a flow of radio multihop transfer, and an apparatus that performs radio packet communication Suitable for use in.
　１００　送受信処理部、１１０　変調部、１２０　送信部、１３０　アンテナ、１４０　受信部、１５０　復調部、１６０　キャリア検出部、２００　送信バッファ部、２１０　パケット生成部、３００　ヘッダ除去部、３１０　データ処理部、４００　送信制御部、４１０　ルーティングテーブル管理部、４２０　再送制御部。 100 transmission / reception processing unit, 110 modulation unit, 120 transmission unit, 130 antenna, 140 reception unit, 150 demodulation unit, 160 carrier detection unit, 200 transmission buffer unit, 210 packet generation unit, 300 header removal unit, 310 data processing unit, 400 Transmission control unit, 410 routing table management unit, 420 retransmission control unit.

Claims (6)

  1. 　データを送信するチャネルが空き状態であった場合は設定されたバックオフ時間待機した後に当該データを送信すると共に、他の装置との間で前記データのマルチホップ転送における送受信を行う送受信処理部と、
    　前記他の装置のうち、前記マルチホップ転送の回数が少ない装置へのデータ送信であるほど、前記バックオフ時間を少なく設定する送信制御部とを備えたマルチホップ無線装置。     A transmission / reception processing unit for transmitting and receiving data in a multi-hop transfer with other devices after waiting for a set backoff time when a channel for transmitting data is idle; ,
    A multi-hop wireless device comprising: a transmission control unit configured to set the back-off time to be smaller as data transmission is performed to a device having a smaller number of multi-hop transfers among the other devices.
  2. 　前記送受信処理部が送信するデータを送信先装置が受信に成功したか否かを判定し、受信に失敗したと判定した場合は前記データの再送制御を行う再送制御部を備え、
    　前記送信制御部は、前記再送制御部による再送回数が少ないほど前記バックオフ時間を少なく設定することを特徴とする請求項１記載のマルチホップ無線装置。     It is determined whether or not the transmission destination device has successfully received the data transmitted by the transmission / reception processing unit, and includes a retransmission control unit that performs retransmission control of the data when it is determined that reception has failed,
    The multi-hop radio apparatus according to claim 1, wherein the transmission control unit sets the back-off time to be smaller as the number of retransmissions by the retransmission control unit is smaller.
  3. 　前記送信制御部は、データの受信信号強度が大きいほど前記バックオフ時間を少なく設定することを特徴とする請求項１記載のマルチホップ無線装置。 The multi-hop wireless device according to claim 1, wherein the transmission control unit sets the back-off time to be smaller as the received signal strength of data is larger.
  4. 　前記送信制御部は、前記マルチホップ転送の回数が少ない装置へのデータ送信であるほど、前記バックオフ時間の上限値を小さく設定することを特徴とする請求項１記載のマルチホップ無線装置。 The multi-hop wireless device according to claim 1, wherein the transmission control unit sets the upper limit value of the back-off time to be smaller as data transmission is performed to a device having a smaller number of multi-hop transfers.
  5. 　前記送信制御部は、前記マルチホップ転送の回数が少ない装置へのデータ送信であるほど、前記バックオフ時間の上限値及び下限値を小さく設定することを特徴とする請求項１記載のマルチホップ無線装置。 2. The multihop radio according to claim 1, wherein the transmission control unit sets an upper limit value and a lower limit value of the back-off time to be smaller as data transmission is performed to a device having a smaller number of multihop transfers. apparatus.
  6. 　複数のマルチホップ無線装置を備えたマルチホップ無線システムであって、
    　前記マルチホップ無線装置は、
    　データを送信するチャネルが空き状態であった場合は設定されたバックオフ時間待機した後に当該データを送信すると共に、他の装置との間で前記データのマルチホップ転送における送受信を行う送受信処理部と、
    　前記他の装置のうち、前記マルチホップ転送の回数が少ない装置へのデータ送信であるほど、前記バックオフ時間を少なく設定する送信制御部とを備え、
    　データ送信先となる装置までの前記マルチホップ転送の回数が少ない装置ほど、前記バックオフ時間が少なく設定されることを特徴とするマルチホップ無線システム。     A multi-hop wireless system comprising a plurality of multi-hop wireless devices,
    The multi-hop wireless device is
    A transmission / reception processing unit for transmitting and receiving data in a multi-hop transfer with other devices after waiting for a set backoff time when a channel for transmitting data is idle; ,
    A transmission control unit that sets the back-off time to be smaller as the data transmission to the device with a smaller number of multi-hop transfers among the other devices,
    A multi-hop wireless system, wherein a device with a smaller number of multi-hop transfers to a device serving as a data transmission destination is set with a smaller back-off time.
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