JP4276150B2 - Frequency channel selection method and radio packet communication apparatus for radio packet communication system - Google Patents

Description

  The present invention relates to a frequency channel selection method and a radio packet communication apparatus in a radio packet communication system for transferring a radio packet between a plurality of base stations (access points).

  The wireless packet communication is a communication form adopted in various systems including a wireless LAN. The wireless LAN standard is being standardized by the IEEE802.11 committee and established as the IEEE802.11 standard (Non-Patent Document 1). In this standard, two communication modes (infrastructure mode and ad hoc mode) are defined.

  The infrastructure mode is composed of a base station (access point) and a terminal station (station) existing within the radio wave coverage (wireless cell), and the base station and its subordinate terminal stations are connected via a wireless medium. This is a communication mode used in a wireless network formed by the above. The base station is connected to a wired network such as Ethernet (registered trademark) and has a relay function between the wireless network and the wired network. That is, when viewed from the terminal station, the base station serves as an entrance to the wired network.

  The ad hoc mode is a communication mode that is used in a closed network that includes only terminal stations and does not require a base station. Terminal stations generally do not have a function of relaying wireless packets, and directly communicate with each other by exchanging wireless packets.

  FIG. 3 shows a configuration example of a conventional wireless packet communication apparatus. In the figure, the wireless packet communication apparatus includes a modulation unit 11, a wireless transmission unit 12, an antenna 13, a wireless reception unit 14, a demodulation unit 15, a packet selection unit 16, and a carrier detection unit 17 as a transmission / reception processing unit 10, and further transmits. A buffer 21, a wireless packet generation unit 22, a transmission control unit 23, and a header removal unit 24 are provided.

  In the wireless packet communication system of IEEE802.11 standard, it is detected (carrier sense) whether the signal is output in the frequency band (frequency channel) used by the local station before transmitting the wireless packet, and the signal is not detected When the frequency channel is determined to be idle, the wireless packet transmission process is started, and when a signal is detected, the transmission process is postponed.

  A wireless signal received via the antenna 13 is input to the wireless reception unit 14. The radio reception unit 14 performs reception processing including frequency conversion, filtering, quadrature detection, and AD conversion on the input radio signal, and outputs the received baseband signal to the demodulation unit 15. When the antenna 13 is not used for transmission, the radio signal on the radio propagation path in the channel is always input, and the radio reception unit 14 uses the RSSI signal indicating the received power intensity of the radio signal as the carrier detection unit 17. Output to.

  The carrier detection unit 17 determines the state of the frequency channel using the input RSSI signal. It is determined that the frequency channel is idle when the value of the received electric field strength is equal to or less than a preset threshold value over a certain period (DIFS + CW). Otherwise, the frequency channel is busy. judge. The carrier detection unit 17 outputs the determination result to the transmission control unit 23 as a carrier sense result.

  On the other hand, the transmission buffer 21 receives data frames from a wired network when the wireless station is a base station and from an upper layer of a device (such as a personal computer) connected to the terminal station when the wireless station is a terminal station. Entered. When the data frame is input, the transmission buffer 21 notifies the transmission control unit 23 that the data frame has been input. Alternatively, the transmission buffer 21 sequentially outputs information related to the accumulated data frames (the number of data frames, the data size, the destination address of the data frame, etc.) to the transmission control unit 23.

  The transmission control unit 23 determines whether or not to start transmission processing based on the data frame accumulation information input from the transmission buffer 21 and the carrier sense result input from the carrier detection unit 17. That is, the start of transmission processing is determined when data frames are accumulated in the transmission buffer 21 and the channel is empty. In other cases, the transmission process is not started. When the transmission control unit 23 determines the start of transmission processing, the transmission control unit 23 instructs the transmission buffer 21 to output a data frame. In response to this instruction, the transmission buffer 21 outputs the data frame accumulated at the head of the buffer to the wireless packet generation unit 22.

  The radio packet generation unit 22 generates a radio packet in which a header configured with control information such as a destination radio station address and a local station address and an error detection code is added to the input data packet, and outputs the radio packet to the modulation unit 11 To do. Modulator 11 performs a predetermined modulation process on the radio packet and outputs the result to radio transmitter 12. The wireless transmission unit 12 performs transmission processing including DA conversion, frequency conversion, filtering, and power amplification on the wireless packet after modulation processing, and transmits the wireless packet from the antenna 13 as a wireless signal.

  The radio signal received via the antenna 13 is converted into a baseband signal by the radio reception unit 14 and input to the demodulation unit 15 as described above. The demodulator 15 demodulates the baseband signal and outputs it to the packet selector 16 as a received packet.

  The packet selection unit 16 analyzes the control information included in the header of the received packet, and outputs the received data packet to the header removing unit 24 if the destination wireless station address matches the own station address. Discard if they do not match. Although detailed description is omitted here, the packet selection unit 16 receives a management packet in which authentication information or the like is described, or a control packet in which delivery confirmation information or the like is described, based on the information. The packet is output to a management packet control unit (not shown) that performs authentication processing and the like, and a control packet processing unit (not shown) that performs delivery confirmation processing and the like.

  The header removing unit 24 removes the header of the received data packet and extracts a data frame. As a received data frame sequence, when the wireless station is a base station, the header is removed to a wired network, and when the wireless station is a terminal station, Output to the upper layer of the connected device.

  By using such a wireless packet communication device, each wireless station can autonomously perform channel access control by carrier sense, and transmit a wireless packet from the base station to the terminal station or from the terminal station to the base station.

By the way, the IEEE802.11 standard enables communication between base stations. A system that performs communication between base stations is called WDS (Wireless Distribution System), and wireless packets are transferred between base stations. For example, a WDS-compatible base station relays between wired networks. In general, in order to construct a wide-range wireless network, it is necessary to connect a plurality of base stations and connect each base station by wire. At this time, a method of transferring a wireless packet by combining an infrastructure mode and a WDS mode and connecting a plurality of base stations via a wireless medium is conceivable. In this method, since a plurality of installed base stations can be wirelessly connected, there is no need to lay a wired network, and a wide-range wireless network can be easily constructed.
IEEE802.11, "Wireless LAN Medium Access Control (MAC) and Physical (PHY) Layer Specifications", August 1999 802.11 high-speed wireless LAN textbook, IDG Japan

  Generally, in wireless communication, wireless packets transmitted simultaneously from a plurality of wireless stations on the same frequency channel interfere with each other and are not normally received. Therefore, a sufficient distance is required between base stations that use the same frequency channel. For example, as shown in FIG. 4, when base stations (APs) that use the same frequency channel are arranged, it is necessary to perform placement design so that radio cells of the base stations do not overlap. However, in the WDS that performs communication between base stations, as shown in FIG. 5, it is necessary for the base station of the communication partner to be included in the radio cell of each base station (AP).

  By the way, the wireless packet communication device of the IEEE802.11 system performs carrier sense for the frequency channel used by the local station when the local station is not transmitting, but does not monitor other frequency channels. It is not possible to receive signals transmitted on other frequency channels. Therefore, in order to transfer wireless packets between base stations and construct a wide-area wireless network, it is necessary to operate all base stations on the same frequency channel. As a result, as shown in FIG. 6 (1), the radio cells are arranged in the vicinity of the base station using the same frequency channel, and the radio cells overlap each other, and the throughput in each radio network is significantly reduced.

  As such a technical problem, in order to improve throughput while including the base station of the communication partner in the radio cell of each base station, it is necessary to use different frequency channels between at least adjacent base stations and A method for transferring wireless packets between stations is required. As an example, as shown in FIG. 6 (2), each base station (AP) includes a plurality of antennas (transmission / reception processing units), and each antenna performs transmission / reception processing and transfer processing corresponding to different frequency channels. There is. That is, each adjacent base station (AP) assigns different # 1 and # 2 as frequency channels used for packet transmission / reception with the terminal station (ST) under its control, and further different frequency channels are used for packet transfer between base stations. This is a method of assigning # 3.

  Alternatively, as shown in FIG. 6 (3), when a base station (AP) transfers a wireless packet to another base station (AP), it is a method of assigning a frequency channel used by the transfer destination base station. . Details of this method will be described later.

  When each of such base stations is provided with a plurality of antennas and used separately for packet transmission / reception with a subordinate terminal station and for packet transfer with another base station, a new problem arises. That is, when transmission / reception processing is performed simultaneously on different frequency channels, power leakage occurs between the antennas.

  The number of frequency channels specified in the IEEE802.11a standard is 4, and the signal bandwidth and the center frequency interval are specified so that the power of the radio signal in each frequency channel does not leak to the adjacent frequency channel. However, it is difficult to produce a filter that ideally cuts out-of-band power, and in an actual wireless packet communication device, slight power leakage to neighboring frequency channels is inevitable. When antennas that use different frequency channels (interference antennas) are far away, the leakage power is not a problem, but when the interference antenna is close to the receiving antenna, a radio signal transmitted from a distant communication partner Is greatly affected and reception becomes difficult.

  For this reason, as shown in FIGS. 6 (2) and 6 (3), in a base station having a plurality of antennas (transmission / reception processing units) and assigning different frequency channels to each antenna, it is important to assign the frequency channel of each antenna. become. For example, when a frequency channel having a large leakage power with respect to the frequency channel for which reception processing is performed is used for transmission, there is a problem that a wireless packet being received cannot be received normally. On the other hand, if the wireless packet transfer process between base stations and the wireless packet transmission / reception process to the subordinate terminal stations are not performed simultaneously, the above problem does not occur, but depending on which process has priority There arises a problem of delay in transfer processing or reduction in efficiency of transmission / reception processing with a terminal station under its control.

  An object of the present invention is to provide a frequency channel selection method and a radio packet communication apparatus of a radio packet communication system that can avoid a decrease in throughput in each radio cell and can transfer radio packets between base stations. .

In a wireless packet communication system in which a plurality of base stations perform packet transmission / reception with subordinate terminal stations on different frequency channels and perform packet transfer between the base stations, the base station transmits packets with subordinate terminal stations. Provided with multiple antennas used for transmission / reception and packet transfer with other base stations, assign different frequency channels to multiple antennas , and send measurement signals transmitted from one antenna assigned frequency channel to others A frequency channel in which leakage power received by another antenna to which the frequency channel is assigned is equal to or less than a predetermined threshold is selected, and a combination of frequency channels to be assigned to a plurality of antennas is obtained from the selected frequency channel .

Also, the first frequency channel is assigned to the first antenna of the plurality of antennas, and the second frequency channel assigned to the second antenna is changed from the first frequency channel to a predetermined direction. While shifting by one channel, select the second frequency channel for which the leakage power for receiving the measurement signal transmitted from the first antenna by the second antenna is equal to or less than a predetermined threshold, and then select the first antenna The assigned frequency channel is replaced with the second frequency selected from the first frequency channel, and the third frequency channel assigned to the second antenna is changed from the selected second frequency channel to a predetermined direction. while shifting by one channel as the threshold leakage power is given to a measuring signal transmitted from the first antenna receives at a second antenna It selects the third frequency channel serving as or less, the first antenna and leakage power while shifting similarly a frequency channel to be allocated to the second antenna selects a frequency channel equal to or less than a predetermined threshold value, and the selected assigning three or more frequency channels in the first and second antennas obtains a combination of a frequency channel (claim 2). Also, the first frequency channel is assigned to the first antenna of the plurality of antennas, and the second frequency channel assigned to the second antenna is changed from the first frequency channel to a predetermined direction. While shifting by one channel, select the second frequency channel for which the leakage power for receiving the measurement signal transmitted from the first antenna by the second antenna is less than or equal to a predetermined threshold, and then the third and subsequent frequencies As the channel, a frequency channel in which the frequency sequentially changes in a predetermined direction from the second frequency channel selected by the frequency interval between the first frequency channel and the selected second frequency channel is selected, and the selected channel is selected. from three or more frequency channels may be obtained a combination of a frequency channel to be allocated to the first antenna and the second antenna Claim 3).

  Further, carrier sense processing may be performed for the selected frequency channel, and the frequency channel used for the operation of the own station may be determined according to the result (claim 4). Furthermore, one frequency channel of the selected frequency channels is used for transmission / reception with a subordinate terminal station, and another frequency channel is used for transmission / reception with each subordinate terminal station at another base station, and It is selected as a frequency channel to be used for packet transfer from the base station to another base station.

A sixth aspect of the present invention relates to a wireless packet communication apparatus in which a plurality of base stations perform packet transmission / reception with a subordinate terminal station on different frequency channels and perform packet transfer between the base stations. Provided with multiple antennas used for transmission / reception and packet transfer with other base stations, assign different frequency channels to multiple antennas, and send measurement signals transmitted from one antenna assigned frequency channel to others Means for selecting a frequency channel in which leakage power received by other antennas to which the frequency channel is assigned is equal to or less than a predetermined threshold value , and obtaining a combination of frequency channels to be assigned to the plurality of antennas from the selected frequency channel .

Also, the first frequency channel is assigned to the first antenna of the plurality of antennas, and the second frequency channel assigned to the second antenna is changed from the first frequency channel to a predetermined direction. While shifting by one channel, select the second frequency channel for which the leakage power for receiving the measurement signal transmitted from the first antenna by the second antenna is equal to or less than a predetermined threshold, and then select the first antenna The assigned frequency channel is replaced with the second frequency selected from the first frequency channel, and the third frequency channel assigned to the second antenna is changed from the selected second frequency channel to a predetermined direction. while shifting by one channel as the threshold leakage power is given to a measuring signal transmitted from the first antenna receives at a second antenna It selects the third frequency channel serving as or less, the first antenna and leakage power while shifting similarly a frequency channel to be allocated to the second antenna selects a frequency channel equal to or less than a predetermined threshold value, and the selected Means for obtaining a combination of frequency channels to be assigned to the first antenna and the second antenna from three or more frequency channels is provided. Also, the first frequency channel is assigned to the first antenna of the plurality of antennas, and the second frequency channel assigned to the second antenna is changed from the first frequency channel to a predetermined direction. While shifting by one channel, select the second frequency channel for which the leakage power for receiving the measurement signal transmitted from the first antenna by the second antenna is less than or equal to a predetermined threshold, and then the third and subsequent frequencies As the channel, a frequency channel in which the frequency sequentially changes in a predetermined direction from the second frequency channel selected by the frequency interval between the first frequency channel and the selected second frequency channel is selected, and the selected channel is selected. It is provided with means for determining a combination of a frequency channel allocated from 3 or more frequency channels in the first and second antennas (Claim 8).

  Further, there may be provided means for performing carrier sense processing on the selected frequency channel and determining a frequency channel to be used for the operation of the own station according to the result (claim 9). In addition, one of the selected frequency channels is used for transmission / reception with a subordinate terminal station, and the other frequency channel is used for transmission / reception with each subordinate terminal station at another base station, and A configuration may be adopted in which the frequency channel is used for packet transfer from the base station to another base station (claim 10).

  In the present invention, the combination of frequency channels that are less affected by power leakage (leakage power value is less than or equal to the threshold value) can be grasped, and channel assignment can be performed to each antenna using the combination. Wireless packets can be transferred without being affected by leakage power between a plurality of base stations performing packet transmission / reception with other terminal stations. Thereby, it is possible to realize a radio packet communication system that transfers radio packets between base stations without reducing the throughput of each radio network.

  FIG. 1 shows a configuration example of a radio packet communication apparatus used in a frequency channel selection method of a radio packet communication system according to the present invention. Here, in addition to one transmission / reception processing unit used for packet transmission / reception with a terminal station under its own station, a configuration example as a base station including one transmission / reception processing unit used for packet transfer to another base station Indicates. FIG. 6 (3) shows an example of the usage state of this base station.

  In the figure, the wireless packet communication device includes transmission / reception processing units 10-1 and 10-2, transmission buffers 21-1 and 21-2, wireless packet generation units 22-1 and 22-2, a transmission control unit 23, and a header removal unit. 24, a transfer control unit 25, a frequency selection control unit 31, and a measurement signal generation unit 32. The transmission / reception processing units 10-1 and 10-2 include a modulation unit 11, a radio transmission unit 12, an antenna 13, a radio reception unit 14, a demodulation unit 15, a packet selection unit 16, and a carrier detection unit 17, respectively. However, the transmission / reception processing unit 10-1 is used for packet transmission / reception with a terminal station under its own station, and frequency channels set in the wireless transmission unit 12 and the wireless reception unit 14 are assigned to at least adjacent base stations. Unlike the frequency channel, it is fixed. On the other hand, the transmission / reception processing unit 10-2 is used for packet transfer to other base stations, and the frequency channels set in the wireless transmission unit 12 and the wireless reception unit 14 are unused and transferred by the transmission / reception processing unit 10-1. Switching is set according to the frequency channel used by the destination base station.

  The configuration and operation of the transmission / reception processing unit 10-1, the transmission buffer 21-1, the wireless packet generation unit 22-1, the transmission control unit 23, and the header removal unit 24 are the same as those of the conventional wireless packet communication device shown in FIG. The wireless packet is transmitted / received to / from the subordinate terminal station. The configuration and operation of the transmission / reception processing unit 10-2 are the same as those of the transmission / reception processing unit 10-1.

  In this configuration example, a transmission packet is generated by the transmission buffer 21-2, the wireless packet generation unit 22-2, and the transfer control unit 25, and is transmitted to the transfer destination base station via the transmission / reception processing unit 10-2.

  Only a data frame (transfer frame) to be transferred to another base station is input to the transmission buffer 21-2, and information on the transfer frame (number of data frames, data size, destination address of the data frame, etc.) is transfer controlled. The unit 25 is notified. In addition, when the reception packet input from the demodulation unit 15 includes a transfer frame, the packet selection unit 16 of the transmission / reception processing unit 10-1 outputs the transfer frame to the transmission buffer 21-2.

  Based on the transfer frame storage information input from the transmission buffer 21-2, the transfer control unit 25 uses one frame of the transfer frames stored in the transmission buffer 21-2, for example, the destination wireless station address of the frame located at the head. Based on the above, the address of the transfer destination base station is identified. Here, the method for associating the transfer frame with the transfer destination base station will not be described in detail. For example, the transfer control unit 25 is realized by providing a list for associating the destination radio station address of the transfer frame with the transfer destination base station. It is possible and other methods may be used. In addition, the transfer control unit 25 includes a list in which the transfer destination base station and the frequency channel used by the transfer destination base station are associated with each other, and the wireless transmission unit 12 and the wireless reception unit 14 of the transmission / reception processing unit 10-2 use the frequency channel. Instruct to send and receive. The wireless transmission unit 12 and the wireless reception unit 14 of the transmission / reception processing unit 10-2 switch the frequency channel for transmission / reception according to the instruction (transfer destination base station) of the transfer control unit 25.

  The carrier detection unit 17 of the transmission / reception processing unit 10-2 outputs the carrier sense result of the frequency channel used by the transfer destination base station to the transfer control unit 25. The transfer control unit 25 determines whether or not to start the transmission process based on the accumulated information of the transfer frame input from the transmission buffer 21-2 and the carrier sense result input from the carrier detection unit 17. That is, when the transfer frame is accumulated in the transmission buffer 21-2 and the frequency channel is empty, the start of the transfer process is determined. When the transfer control unit 25 determines to start the transfer process, the transfer control unit 25 instructs the transmission buffer 21-2 to output a transfer frame. In response to this instruction, the transmission buffer 21-2 outputs the transfer frame stored at the head of the buffer to the wireless packet generation unit 22-2. Thereafter, the transfer frame is similarly transmitted as a wireless packet from the transmission / reception processing unit 10-2.

  Thus, when a base station transmits a radio packet to a transfer destination base station, the transfer destination base station uses the frequency channel used for packet transmission / reception with the subordinate terminal station, thereby the terminal station The transmission right can be acquired by the carrier sense in the same column as the above, and packet transfer between base stations can be realized. Also, in the transfer destination base station, in the frequency channel used by the own station, in the same way as the reception process of the radio packet transmitted from the subordinate terminal station, the radio packet transferred from the other base station to the own station is transmitted. Reception processing can be performed. The ACK packet by this reception process is transmitted on the same frequency channel, received by the wireless reception unit 14 of the transmission / reception processing unit 10-2 of the transfer source base station, and transferred via the demodulation unit 15 and the packet selection unit 16 to the transfer control unit 25. Is notified of ACK information.

  Now, a frequency channel selection method for independently operating the frequency channel used by the transmission / reception processing unit 10-1 and the frequency channel used by the transmission / reception processing unit 10-2 in such a wireless packet communication apparatus will be described. .

  The basic procedure is to assign different frequency channels to two antennas, and obtain a combination of frequency channels whose received power is less than or equal to a predetermined threshold when a radio signal transmitted from one antenna is received by the other antenna. , And select as a set of frequency channels to be assigned to each transmission / reception processing unit. When there are three or more antennas and transmission / reception processing units, the same processing is performed between the respective antennas, and a combination of frequency channels with which leakage power is less than or equal to an allowable value is determined. Hereinafter, a specific description will be given with reference to FIGS. 1 and 2.

  First, a reference frequency channel is selected (FIG. 2, S11). As the selection criterion, for example, carrier sensing is performed for each frequency channel, and the lowest frequency channel is selected from the idle frequency channels. The reference frequency channel number is L. Next, N is the total number of selectable channels, L is given to the variable K, and L + 1 is given to the variable M (S12). That is, the variable K and the variable M correspond to adjacent frequency channel numbers. Next, frequency channel K is assigned to antenna 1 included in the wireless packet communication device, frequency channel M is assigned to antenna 2, a measurement signal is transmitted from antenna 1 (frequency channel K), and antenna 2 (frequency channel M) is assigned. The leakage power is measured (S13).

  The processing so far is performed under the control of the frequency selection control unit 31 shown in FIG. First, the measurement signal generator 32 generates a measurement signal for the frequency channel K and transmits the measurement signal from the antenna 13 of the transmission / reception processor 10-1, and the wireless transmission of the transmission / reception processor 10-2 via the transfer controller 25. The frequency channel M is set in the unit 12 and the wireless receiving unit 14. Then, the leakage power of the measurement signal for the frequency channel M is measured by the antenna 13, the radio reception unit 14, and the carrier detection unit 17 of the transmission / reception processing unit 10-2. The value of the leakage power is notified to the transfer control unit 25, and the following processing is performed.

  The leakage power from the frequency channel K to the frequency channel M is compared with a predetermined threshold value (S14). Here, when the leakage power is larger than the threshold value, it is determined that the frequency channel M cannot be used due to power leakage from the frequency channel K, and the value of the variable M is updated to M + 1 (S15). The transfer control unit 25 switches the frequency channel from M to M + 1 for the wireless transmission unit 12 and the wireless reception unit 14 of the transmission / reception processing unit 10-2. At this time, if the variable M is larger than the total number of channels N, the process is terminated, and if it is less than N, the process returns to step S13 (S17).

  On the other hand, when the leakage power is smaller than the threshold value, the frequency channel M is less affected by the power leakage from the frequency channel K, and is registered as a frequency channel to be used, and the value of the variable K is updated to M. The value is updated to M + 1 (S16). The transfer control unit 25 instructs the frequency selection control unit 31 to switch the frequency channel from K to M, and switches the frequency channel from M to the wireless transmission unit 12 and the wireless reception unit 14 of the transmission / reception processing unit 10-2. Switch to M + 1. At this time, if the variable M is larger than the total number of channels N, the process is terminated, and if it is N or less, the process returns to step S13 (S17). That is, the same frequency channel selection process is continued with the frequency channel M registered as usable as a reference. As a result, frequency channels (for example, L + 3, L + 6,...) With appropriate frequency intervals with small power leakage are registered as usable with the frequency channel L as a reference.

  Each wireless packet communication device performs carrier sense processing only for the frequency channels registered in advance by the above processing at the time of startup, and determines the frequency channel to be operated according to the result. For example, the frequency channel with the smallest received power is selected and the operation is started. As a result, it is possible to perform transmission / reception or transfer processing of wireless packets independently without being affected by leakage power in each frequency channel.

  By assigning the frequency channel selected in this way to each base station, the base station uses the frequency channel used in the transfer destination base station while performing packet transmission / reception with the terminal station under its control. Packet transfer can be performed. Further, when there are a plurality of transmission / reception processing units for packet transfer, packet transfer can be performed simultaneously to a plurality of transfer destination base stations.

  In the present embodiment, a method for selecting a usable frequency channel by actually measuring the leakage power of each frequency channel is shown. However, after determining a set of frequency channels whose leakage power is less than or equal to the threshold value in step S16 of FIG. 2, the processing is terminated, and frequency channels having a higher center frequency are sequentially selected by the same frequency interval as the center frequency interval. May be.

  In addition, assuming a wireless packet communication system that actually connects a plurality of wireless networks with a wireless medium, a wireless packet communication device (master base station) connected to the wired network and other wireless packet communication via only the wireless medium There are two types of devices, a wireless packet communication device (slave base station) connected to the device. Both of these devices can be realized by the configuration of the wireless packet communication device shown in FIG. However, a function for managing the route of the transfer packet is added to the master base station. Further, the transfer data frame sequence input to the transmission buffer 21-2 of the slave base station is only the one output from the packet selection unit 16 of the transmission / reception processing unit 10-1.

  In this embodiment, the transmission buffer 21-1 to which the transmission data frame sequence is input and the transmission buffer 21-2 to which the transfer data frame sequence is input are individually configured. It can be a buffer. In this case, the function of the transfer control unit 25 may be performed by the transmission control unit 23 to manage the transmission buffer.

The figure which shows the structural example of the radio | wireless packet communication apparatus used for the frequency channel selection method of the radio | wireless packet communication system of this invention. The flowchart which shows the process sequence of the frequency channel selection method of this invention. The figure which shows the structural example of the conventional radio | wireless packet communication apparatus. The figure which shows the example of arrangement | positioning of a radio cell. The figure which shows the example of arrangement | positioning of a radio cell. The figure explaining the example of a setting of the frequency channel for the packet transfer between base stations.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transmission / reception processing part 11 Modulation part 12 Radio transmission part 13 Antenna 14 Radio reception part 15 Demodulation part 16 Packet selection part 17 Carrier detection part 21 Transmission buffer 22 Radio packet generation part 23 Transmission control part 24 Header removal part 25 Transfer control part 31 Frequency Selection control unit 32 Measurement signal generator

Claims (10)

In a wireless packet communication system in which a plurality of base stations perform packet transmission / reception with a subordinate terminal station on different frequency channels and perform packet transfer between base stations,
The base station comprises a plurality of antennas used for packet transmission / reception with a subordinate terminal station and packet transfer with other base stations ,
Different frequency channels are allocated to the plurality of antennas , and a measurement signal transmitted from one antenna to which a frequency channel is allocated is received by another antenna to which another frequency channel is allocated . A frequency channel selection method for a radio packet communication system, comprising: selecting a frequency channel that is equal to or less than a threshold value ; and obtaining a combination of frequency channels to be assigned to the plurality of antennas from the selected frequency channel. The frequency channel selection method of the wireless packet communication system according to claim 1,
A first frequency channel is assigned to a first antenna of the plurality of antennas, and a second frequency channel to be assigned to a second antenna is changed from the first frequency channel to a predetermined direction. While shifting by one channel, select the second frequency channel for which the leakage power for receiving the measurement signal transmitted from the first antenna by the second antenna is equal to or less than a predetermined threshold, and then select the first antenna A frequency channel to be allocated is replaced with the selected second frequency from the first frequency channel, and a third frequency channel to be allocated to a second antenna is changed from the selected second frequency channel to the predetermined one. Receive while shifting by one channel so as to change the direction, the measuring signal transmitted from the first antenna at a second antenna Mode power selects the third frequency channel equal to or less than a predetermined threshold value, the first antenna and the frequency channel leakage power while shifting similarly a frequency channel to be allocated to the second antenna is equal to or lower than a predetermined threshold value or less selected, frequency channel selection method for a radio packet communication system, wherein from said selected three or more frequency channels to obtain the combination of the frequency channels allocated to the first and second antennas. The frequency channel selection method of the wireless packet communication system according to claim 1,
A first frequency channel is assigned to a first antenna of the plurality of antennas, and a second frequency channel to be assigned to a second antenna is changed from the first frequency channel to a predetermined direction. While shifting by one channel, select the second frequency channel for which the leakage power for receiving the measurement signal transmitted from the first antenna by the second antenna is less than or equal to a predetermined threshold, and then the third and subsequent frequencies as the channel, select the second frequency channel in frequency from the second frequency channel is sequentially changed to the predetermined direction that is the selected one frequency interval between the frequency channels that are the selection and first frequency channel, seeking a combination of a frequency channel to be allocated to the first antenna and the second antenna from the selected three or more frequency channels Frequency channel selection method for a radio packet communication system, characterized in that. In the frequency channel selection method of the radio | wireless packet communication system in any one of Claims 1-3,
A frequency channel selection method for a radio packet communication system, wherein carrier sense processing is performed on the selected frequency channel, and a frequency channel used for operation of the local station is determined according to the result. In the frequency channel selection method of the wireless packet communication system according to any one of claims 1 to 4,
One frequency channel of the selected frequency channels is used for transmission / reception with the subordinate terminal station, and the other frequency channel is used for transmission / reception with each subordinate terminal station at another base station, and A frequency channel selection method for a wireless packet communication system, wherein the frequency channel is selected as a frequency channel used for packet transfer from a base station to another base station. In a wireless packet communication apparatus in which a plurality of base stations perform packet transmission / reception with subordinate terminal stations on different frequency channels and perform packet transfer between base stations,
The base station comprises a plurality of antennas used for packet transmission / reception with a subordinate terminal station and packet transfer with other base stations,
Different frequency channels are allocated to the plurality of antennas, and a measurement signal transmitted from one antenna to which a frequency channel is allocated is received by another antenna to which another frequency channel is allocated . A radio packet communication apparatus comprising: means for selecting a frequency channel that is equal to or less than a threshold value and obtaining a combination of frequency channels to be assigned to the plurality of antennas from the selected frequency channel . The wireless packet communication device according to claim 6, wherein
A first frequency channel is assigned to a first antenna of the plurality of antennas, and a second frequency channel to be assigned to a second antenna is changed from the first frequency channel to a predetermined direction. While shifting by one channel, select the second frequency channel for which the leakage power at which the measurement signal transmitted from the first antenna is received by the second antenna is less than or equal to a predetermined threshold, and then select the first antenna A frequency channel to be allocated is replaced with the selected second frequency from the first frequency channel, and a third frequency channel to be allocated to a second antenna is changed from the selected second frequency channel to the predetermined one. Receive while shifting by one channel so as to change the direction, the measuring signal transmitted from the first antenna at a second antenna Mode power selects the third frequency channel equal to or less than a predetermined threshold value, the first antenna and the frequency channel leakage power while shifting similarly a frequency channel to be allocated to the second antenna is equal to or lower than a predetermined threshold value or less A wireless packet communication apparatus comprising: means for selecting and obtaining a combination of frequency channels to be allocated to the first antenna and the second antenna from the selected three or more frequency channels . The wireless packet communication device according to claim 6, wherein
A first frequency channel is assigned to a first antenna of the plurality of antennas, and a second frequency channel to be assigned to a second antenna is changed from the first frequency channel to a predetermined direction. While shifting by one channel, the second frequency channel for which the leakage power for receiving the measurement signal transmitted from the first antenna by the second antenna is less than a predetermined threshold is selected, and then the third and subsequent frequencies are selected. as the channel, select the second frequency channel in frequency from the second frequency channel is sequentially changed to the predetermined direction that is the selected one frequency interval between the frequency channels that are the selection and first frequency channel, seeking a combination of a frequency channel to be allocated to the first antenna and the second antenna from the selected three or more frequency channels Wireless packet communication apparatus characterized by comprising means. In the wireless packet communication apparatus according to any one of claims 6 to 8,
A radio packet communication apparatus comprising: means for performing carrier sense processing on the selected frequency channel, and determining a frequency channel to be used for operation of the local station according to the result. In the radio | wireless packet communication apparatus in any one of Claims 6-9,
One frequency channel of the selected frequency channels is used for transmission / reception with the subordinate terminal station, and another frequency channel is used for transmission / reception with each subordinate terminal station at another base station, and A radio packet communication apparatus, characterized in that it is configured as a frequency channel used for packet transfer from a base station to another base station.

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