WO2010074248A1 - 無線通信システム、無線基地局および閾値設定方法 - Google Patents
無線通信システム、無線基地局および閾値設定方法 Download PDFInfo
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- WO2010074248A1 WO2010074248A1 PCT/JP2009/071643 JP2009071643W WO2010074248A1 WO 2010074248 A1 WO2010074248 A1 WO 2010074248A1 JP 2009071643 W JP2009071643 W JP 2009071643W WO 2010074248 A1 WO2010074248 A1 WO 2010074248A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
- H04W72/541—Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
- H04W88/08—Access point devices
Definitions
- the present invention relates to a radio communication system, a radio base station, and a threshold setting method for allocating at least one communication channel whose interference level is lower than a channel allocation threshold among a plurality of communication channels to a radio terminal.
- the radio base station measures the interference level in a plurality of communication channels, and determines a low-interference communication channel whose measured interference level is lower than the channel allocation threshold as an empty channel.
- a radio base station allocates a low interference communication channel to a radio terminal using carrier sense.
- the channel assignment threshold used for carrier sense is generally set to the same value in each radio base station and each communication channel.
- a broadband wireless communication system employing a multicarrier wireless communication scheme such as orthogonal frequency division multiple access (OFDMA) has recently attracted attention (see, for example, Patent Document 1).
- OFDMA orthogonal frequency division multiple access
- a plurality of communication channels called subchannels can be assigned to one wireless terminal.
- the wireless base station and the wireless terminal can increase the communication capacity in the wireless communication.
- a wireless base station assigns a channel to one wireless terminal using carrier sense. Many communication channels may be assigned to wireless terminals. In this case, the following problem occurs.
- the second radio base station located around the first radio base station performs carrier sense.
- the number of communication channels determined as empty channels decreases, and the number of communication channels that can be allocated to the second wireless terminal under its own station decreases. For this reason, the communication capacity and communication quality in the second radio base station are not guaranteed, and there is a problem that fairness between the first radio base station and the second radio base station is not ensured.
- the present invention guarantees the communication capacity and communication quality in each radio base station when a plurality of communication channels can be assigned to radio terminals and channel assignment is performed using carrier sense. It is an object of the present invention to provide a radio communication system, a radio base station, and a threshold setting method that can ensure fairness of data.
- the present invention has the following features.
- the first feature of the present invention is that a first low-interference communication with a first wireless terminal (for example, the wireless terminal 2A) in which the interfered level of a plurality of communication channels within a predetermined frequency band is lower than a threshold value.
- the first radio base station radio base station 1A
- the second radio terminal the interfered level among the interfered levels in the plurality of communication channels within the predetermined frequency band is lower than the threshold value.
- a wireless communication system (wireless communication system 10) comprising a second wireless base station (wireless base station 1B) to which a second low interference communication channel is assigned, and a channel assignment threshold for determining the first low interference communication channel
- the first channel allocation threshold is different from the second channel allocation threshold that is a channel allocation threshold for determining the second low-interference communication channel.
- a second feature of the present invention relates to the first feature of the present invention, wherein the first threshold setting unit (threshold setting unit 122A) for setting the first channel allocation threshold and the second channel allocation threshold are set.
- a second threshold value setting unit (threshold value setting unit 122B), wherein the first threshold value setting unit uses the first random number generated based on a value unique to the first radio base station, and uses the channel allocation threshold value. Is set for each communication channel, and the second threshold setting unit sets the channel allocation threshold for each communication channel using a second random number generated based on a value unique to the second radio base station. The gist is to set.
- the first threshold setting unit sets the first channel allocation threshold for each communication channel, thereby defining a communication channel with a high allocation priority and a communication channel with a low allocation priority. Is done.
- the second threshold setting unit sets the second channel allocation threshold for each communication channel, a communication channel with a high allocation priority and a communication channel with a low allocation priority are defined.
- the first threshold setting unit uses a first random number generated for each communication channel based on a value unique to the first radio base station, and the second threshold setting unit is unique to the second radio base station. Since the second random number generated for each communication channel based on the value is used, different priorities are assigned to the first radio base station and the second radio base station.
- a third feature of the present invention relates to the second feature of the present invention, wherein the first threshold value setting unit includes a difference between the first random number generated for each communication channel and the first channel allocation threshold value. Is multiplied by a predetermined coefficient (coefficient ⁇ ) for adjusting the result, and the result obtained by multiplying the multiplication result of the first random number and the predetermined coefficient and a reference value serving as a reference for the channel allocation threshold is obtained as the communication channel. And the second threshold value setting unit multiplies the second random number generated for each communication channel by the predetermined coefficient to obtain the second random number and the predetermined threshold value.
- the gist of the present invention is to set a result of adding a multiplication result with a coefficient and the reference value as the second channel allocation threshold value corresponding to the communication channel.
- a fourth feature of the present invention relates to the second or third feature of the present invention, wherein the first threshold value setting unit is provided in the first radio base station, and the second threshold value setting unit is The gist is that it is provided in two radio base stations.
- a fifth feature of the present invention relates to the second or third feature of the present invention, and further comprises a server device (server 4) for managing the first radio base station and the second radio base station,
- server 4 for managing the first radio base station and the second radio base station
- the gist is that the first threshold value setting unit and the second threshold value setting unit are provided in the server device.
- a sixth feature of the present invention is according to any one of the first to fifth features of the present invention, and is characterized in that the communication channel is configured according to an orthogonal frequency division multiple access scheme and a time division multiple access scheme. To do.
- a seventh feature of the present invention relates to the sixth feature of the present invention, wherein the first threshold value setting unit is responsive to the orthogonal frequency division multiple access scheme in addition to a value unique to the first radio base station.
- the first channel allocation threshold is set for each communication channel using the first random number generated for each communication channel based on a subchannel number and a time slot number corresponding to the time division multiple access method.
- the second threshold value setting unit uses the second random number generated for each communication channel based on the subchannel number and the time slot number in addition to a value unique to the second radio base station.
- the second channel allocation threshold is set for each communication channel.
- the eighth feature of the present invention is that at least one interference level in a plurality of communication channels is measured, and at least one low interference communication channel whose measured interference level is lower than a channel allocation threshold is set to a wireless terminal (for example, wireless terminal 2A).
- a threshold setting unit (threshold setting unit 122A) that sets the channel allocation threshold for each of the communication channels, and the threshold setting unit is connected to the radio base station. The gist is to set the channel allocation threshold for each communication channel using a random number generated for each communication channel based on a unique value.
- the ninth feature of the present invention is that the first radio base station communicates with the first radio terminal the first low-interference communication in which the interfered level of a plurality of communication channels within a predetermined frequency band is lower than the channel allocation threshold. Allocating a channel, and second low-interference communication in which a second radio base station has a level of interference among a plurality of communication channels within the predetermined frequency band lower than the channel allocation threshold for a second radio terminal.
- a threshold setting method for setting the channel allocation threshold, the channel allocation threshold being a channel allocation threshold for determining the first low interference communication channel, and the second low allocation The gist is that it is different from the second channel allocation threshold value, which is a channel allocation threshold value for determining the interference communication channel.
- a plurality of communication channels can be allocated to radio terminals and channel allocation is performed using carrier sense, communication capacity and communication quality in each radio base station are guaranteed, and between radio base stations Wireless communication system, wireless base station, and threshold setting method can be provided.
- FIG. 1 is an overall schematic configuration diagram of a wireless communication system according to an embodiment of the present invention. It is a functional block diagram which shows the structure of the wireless base station which concerns on embodiment of this invention. It is a figure which shows a channel allocation state in case the channel allocation threshold value is set to the fixed value as a comparative example of embodiment of this invention. It is a figure which shows an example of the channel allocation state in the radio
- FIG. 1 is an overall schematic configuration diagram of a radio communication system 10 according to the present embodiment.
- the wireless communication system 10 has a configuration based on the next generation PHS (Personal Handyphone System).
- the radio communication system 10 employs an orthogonal frequency division multiple access (OFDMA) system and a time division multiple access (TDMA) system as multiplexing systems, and a time division duplex (TDD) system as duplex systems.
- OFDMA orthogonal frequency division multiple access
- TDMA time division multiple access
- TDD time division duplex
- the radio communication system 10 includes a radio base station 1A, a radio base station 1B, a radio terminal 2A, a radio terminal 2B, and a radio terminal 2C.
- the wireless base station 1A assigns a communication channel to the wireless terminal 2A in response to an assignment request from the wireless terminal 2A located in its own cell (microcell) 3A, and wirelessly communicates with the wireless terminal 2A using the assigned communication channel. Execute communication. Similarly, the radio base station 1A allocates a communication channel to the radio terminal 2C, and executes radio communication with the radio terminal 2C using the assigned communication channel.
- the radio base station 1B allocates a communication channel to the radio terminal 2B located in its own cell (microcell) 3B, and executes radio communication with the radio terminal 2B using the assigned communication channel.
- the radio base station 1A can assign a plurality of communication channels to the radio terminal 2A and the radio terminal 2C, respectively, and dynamically change the assigned communication channel.
- the radio base station 1B can allocate a plurality of communication channels to the radio terminal 2B and dynamically change the assigned communication channels.
- the entire frequency band in the radio communication system 10 is frequency-divided into a subchannels according to the OFDMA scheme, and b times each of uplink and downlink in one frame period of the radio communication system 10 according to the TDMA scheme. Time is divided into slots.
- a ⁇ b communication channels are configured in each uplink and downlink.
- Each communication channel configured in this way is configured using one time slot and one subchannel, and is called a physical resource unit (PRU) in the next generation PHS.
- PRU physical resource unit
- the radio base station 1A and the radio base station 1B perform autonomous distributed channel assignment. That is, the radio base station 1A detects a radio signal transmitted / received by the radio base station 1B, determines a communication channel to which the radio base station 1B is assigned, and sets a communication channel to which the radio base station 1B has not been assigned to the radio terminal 2A. Alternatively, it is assigned to the wireless terminal 2C. Similarly, the radio base station 1B detects a radio signal transmitted / received by the radio base station 1A, determines a communication channel to which the radio base station 1A is assigned, and assigns a communication channel to which the radio base station 1A has not been assigned to the radio terminal. Assign to 2B. Such processing is called carrier sense as described above, and interference between the radio base station 1A and the radio base station 1B is autonomously avoided.
- the radio base station 1A allocates to the radio terminal 2A a communication channel whose interference level from an interference source (for example, the radio base station 1B and the radio terminal 2B) is lower than the channel allocation threshold among the a ⁇ b communication channels. That is, in the present embodiment, the radio base station 1A measures the interfered level in a plurality of communication channels, and designates the first low-interference communication channel whose measured interfered level is lower than the first channel allocation threshold as the first radio terminal ( A first radio base station assigned to at least one radio terminal 2A or 2C) is configured.
- the radio base station 1B wirelessly transmits a communication channel whose interference level from an interference source (for example, the radio base station 1A, the radio terminal 2A, and the radio terminal 2C) is lower than the channel allocation threshold among the a ⁇ b communication channels. Assign to terminal 2A.
- the radio base station 1B measures the interfered level in a plurality of communication channels, and designates the second low-interference communication channel whose measured interfered level is lower than the second channel allocation threshold as the second radio terminal (wireless terminal).
- 2B) constitutes a second radio base station to be assigned at least one.
- the plurality of communication channels have a predetermined frequency band (see FIGS. 3 and 4).
- the radio base station 1B allocates and allocates the communication channel to the radio terminal 2B. Voice communication or data communication is performed using the communication channel.
- the radio base station 1B performs carrier sense even when other radio terminals communicate, but the carrier sense result in the communication channel to which the radio base station 1A is assigned exceeds the channel assignment threshold. For this reason, the radio base station 1B allocates communication channels specified by other subchannels and time slots that have a carrier sense result equal to or less than the channel allocation threshold.
- the radio base station 1A occupies the frequency band and the communication time zone the radio base station 1B cannot communicate.
- the radio base station 1B occupies the frequency band and the communication time zone the radio base station 1A cannot communicate.
- the channel allocation threshold value is optimally set for each of the radio base station 1A and the radio base station 1B, thereby guaranteeing the lower limit of the communication capacity in each radio base station / radio terminal, and each radio base station / radio terminal.
- FIG. 2A is a functional block diagram showing the configuration of the radio base station 1A.
- the radio base station 1A includes an antenna unit 101A, a radio communication unit 110A, a control unit 120A, a wired communication unit 130A, and a storage unit 140A.
- the wireless communication unit 110A transmits / receives a wireless signal to / from the wireless terminal 2A or the wireless terminal 2C via the antenna unit 101A.
- the antenna unit 101A may be an adaptive array antenna configured using a plurality of antennas.
- 120 A of control parts are comprised by CPU, for example, and control the various functions which 1 A of radio base stations comprise.
- the storage unit 140A is configured by a memory, for example, and stores various information used for control and the like in the radio base station 1A.
- the wired communication unit 130A functions as an interface with a wired communication network.
- the radio communication unit 110A includes a radio signal transmission unit 111A, a radio signal reception unit 112A, a signal processing unit 113A, and an interference level measurement unit 114A.
- the signal processing unit 113A encodes data to be transmitted to the wireless terminal 2A or the wireless terminal 2C, and modulates the encoded data.
- the signal processing unit 113A performs serial / parallel conversion and inverse fast Fourier transform (IFFT) on the modulated data.
- IFFT inverse fast Fourier transform
- the OFDM signal generated in this way is input to the radio signal transmission unit 111A.
- the radio signal transmission unit 111A includes a power amplifier, an up-converter, and the like, converts the input OFDM signal into a radio signal, and transmits the radio signal to the radio terminal 2A or the radio terminal 2C.
- the radio signal reception unit 112A includes a low noise amplifier, a down converter, and the like, converts the radio signal received from the radio terminal 2A into an OFDM signal, and inputs the OFDM signal to the signal processing unit 113A.
- the signal processing unit 113A performs demodulation and decoding after fast Fourier transform (FFT) and parallel / serial conversion of the OFDM signal.
- FFT fast Fourier transform
- the interference level measurement unit 114A measures the received power of the radio signal received from the interference source (for example, the radio base station 1B and the radio terminal 2B) as the interfered level. Specifically, the interference level measurement unit 114A measures the interfered level for each of the a ⁇ b communication channels.
- the control unit 120A includes an information acquisition unit 121A, a threshold setting unit 122A, and a channel allocation unit 123A.
- the information acquisition unit 121A acquires various types of information used for setting the first channel allocation threshold from the storage unit 140A.
- the information acquisition unit 121A acquires a value unique to the radio base station 1A, a subchannel number that identifies a subchannel, and a time slot number that identifies a time slot.
- a base station identifier BSID
- a serial number of the radio base station 1A or the like can be used as the value unique to the radio base station 1A.
- BSID base station identifier
- the threshold setting unit 122A constitutes a first threshold setting unit that sets the first channel allocation threshold for each of the a ⁇ b communication channels based on the information acquired by the information acquisition unit 121A.
- the threshold setting unit 122A generates a random number for each communication channel (hereinafter referred to as a first random number) based on the BSID, and sets a first channel allocation threshold for each communication channel.
- the threshold setting unit 122A uses the BSID / subchannel number / slot number as an initial value of a random code (PN code), and obtains an individual first channel allocation threshold for each BSID / subchannel number / slot number. Details of the method for setting the first channel allocation threshold will be described later.
- the first channel allocation threshold set by the threshold setting unit 122A is stored in the storage unit 140A. Note that the setting of the first channel allocation threshold is executed, for example, when the radio base station 1A is installed.
- the channel allocation unit 123A has a function of allocating a communication channel to the radio terminal 2A or the radio terminal 2C, a function of managing information of an allocated communication channel (hereinafter, allocation information), and a function of releasing the allocated communication channel. .
- the channel assignment unit 123A compares the interfered level measured for each communication channel by the interference level measurement unit 114A with the first channel assignment threshold, and the first low interference communication channel whose interference level is lower than the first channel assignment threshold. Is identified. At that time, the channel allocation unit 123A acquires the corresponding first channel allocation threshold value from the storage unit 140A for each communication channel, and uses the acquired first channel allocation threshold value for comparison with the interfered level. Then, the channel assignment unit 123A assigns the specified first low interference communication channel to the wireless terminal 2A or the wireless terminal 2C.
- FIG. 2B is a functional block diagram showing the configuration of the radio base station 1B. Here, the description overlapping with that of the radio base station 1B is omitted.
- the radio base station 1B includes an antenna unit 101B, a radio communication unit 110B, a control unit 120B, a wired communication unit 130B, and a storage unit 140B.
- the radio communication unit 110B includes a radio signal transmission unit 111B, a radio signal reception unit 112B, a signal processing unit 113B, and an interference level measurement unit 114B.
- the control unit 120B includes an information acquisition unit 121B, a threshold setting unit 122B, and a channel allocation unit 123B.
- the interference level measurement unit 114B measures the received power of the radio signal received from the interference source (for example, the radio base station 1A, the radio terminal 2A, and the radio terminal 2C) as the interfered level. Specifically, the interference level measurement unit 114B measures the interfered level for each of the a ⁇ b communication channels.
- the information acquisition unit 121B acquires a value specific to the radio base station 1B (here, BSID), a subchannel number that identifies a subchannel, and a time slot number that identifies a time slot. .
- BSID a value specific to the radio base station 1B
- subchannel number that identifies a subchannel
- time slot number that identifies a time slot.
- the threshold setting unit 122B configures a second threshold setting unit that sets the second channel allocation threshold for each of the a ⁇ b communication channels based on the information acquired by the information acquisition unit 121B.
- the threshold setting unit 122B generates a random number (hereinafter referred to as a second random number) for each communication channel based on the BSID, and sets a second channel allocation threshold for each communication channel.
- the second channel allocation threshold set by the threshold setting unit 122B is stored in the storage unit 140B. Note that the setting of the second channel assignment threshold is executed, for example, when the radio base station 1B is installed.
- the channel assignment unit 123B has a function of assigning a communication channel to the wireless terminal 2B, a function of managing assignment information of the assigned communication channel, and a function of releasing the assigned communication channel.
- the channel assignment unit 123B compares the interfered level measured for each communication channel by the interference level measurement unit 114B with the second channel assignment threshold, and identifies a low-interference communication channel whose interference level is lower than the second channel assignment threshold. To do.
- the channel allocation unit 123B acquires the corresponding second channel allocation threshold value from the storage unit 140B for each communication channel, and uses the acquired second channel allocation threshold value for comparison with the interfered level. Then, the channel assignment unit 123B assigns the specified second low interference communication channel to the radio terminal 2B.
- FIG. 3 is a diagram showing a relationship between the channel assignment threshold and the interfered level when the channel assignment threshold is set to a constant value as a comparative example of the present embodiment.
- the channel allocation threshold is set to ⁇ 80 dBm for all the communication channels that can be specified by the radio base station 1A and the communication channels that can be specified by the radio base station 1B. It is assumed that all communication channels are assigned to the terminal 2A and the wireless terminal 2C. That is, the radio base station 1A occupies a frequency band and a communication time band. In such a situation, since the interfered level exceeds the channel allocation threshold in all communication channels, the radio base station 1B cannot allocate a communication channel to the radio terminal 2B.
- FIG. 4 is a diagram showing a channel allocation situation when channel allocation thresholds are set unevenly in the radio base station 1A and the radio base station 1B according to the present embodiment.
- a communication channel that is not allocated is indicated by shading.
- a different first channel assignment threshold is set for each communication channel and a different channel assignment threshold is set for each second communication channel within a range of minimum -120 dBm to maximum -45 dBm.
- a communication channel having a high first channel assignment threshold and a communication channel having a high second channel assignment threshold are being assigned.
- the first channel allocation threshold of the communication channel of the subchannel number 1 and the time slot number 1 is ⁇ 55 dBm, which is high, and is being allocated.
- the second channel allocation threshold value of the communication channel of subchannel number 1 and time slot number 1 is ⁇ 105 dBm, which is low, and is not being allocated.
- the first channel allocation threshold of the communication channels of the subchannel number 1 and the time slot number 2 is ⁇ 100 dBm, which is low, and is not being allocated.
- the second channel allocation threshold of the communication channels of subchannel number 1 and time slot number 2 is -50 dBm, which is high, and is being allocated.
- a communication channel is defined.
- each wireless base station is assigned in order from the communication channel with the highest priority, and conversely, the communication channel with the lower priority is difficult to use. Therefore, the possibility that each radio base station occupies the frequency band and communication time zone can be reduced, and even when there is a bias in the number of radio terminals accommodated between radio base stations, communication channel allocation between radio base stations is Evenly close.
- FIG. 5 is a flowchart showing the detailed operation of the radio base station 1A, specifically, the details of the first channel allocation threshold setting method. The processing flow of FIG. 5 is also executed in the radio base station 1B.
- a first channel allocation threshold is set for one communication channel that is a threshold setting target.
- step S1 the information acquisition unit 121A acquires each information of the BSID lower x bits of the radio base station 1A, the subchannel number of the communication channel targeted for threshold setting, and the time slot number.
- the threshold setting unit 122A sets the information acquired by the information acquisition unit 121A in step S1 as the initial value of the random code. Note that the threshold setting unit 122A incorporates an encoder (or an arithmetic algorithm) that generates a random code.
- step S3 the threshold setting unit 122A extracts a random number (first random number) y bits from the encoder and converts it into a decimal (decimal number) display.
- step S4 the threshold value setting unit 122A multiplies the first random number converted into the decimal display in step S3 by a coefficient ⁇ .
- the coefficient ⁇ is used to adjust the difference between the first channel allocation thresholds assigned to the communication channels.
- the coefficient ⁇ is determined empirically from simulation or the like. In the example of FIG. 4, the difference in the first channel allocation threshold is set to 5 dB by the coefficient ⁇ .
- step S5 the threshold value setting unit 122A adds the multiplication result of the first random number and the coefficient ⁇ obtained in step S4 and the reference value serving as a reference for the first channel allocation threshold value.
- step S6 the threshold setting unit 122A sets the addition result obtained in step S5 as the first channel allocation threshold of the communication channel targeted for threshold setting.
- step S7 the threshold setting unit 122A determines whether or not the setting of the first channel allocation threshold has been completed for all communication channels. If there is a communication channel for which the first channel allocation threshold is not set, the process returns to step S1, and the threshold setting process for the next communication channel targeted for threshold setting is executed.
- the threshold setting unit 122A sets the first channel allocation threshold for each communication channel, so that the communication channel with the higher allocation priority is allocated.
- a communication channel with a low priority is defined.
- the threshold setting unit 122B sets the second channel allocation threshold for each communication channel, thereby defining a communication channel with a high allocation priority and a communication channel with a low allocation priority.
- the threshold setting unit 122A uses a first random number generated for each communication channel based on a value unique to the radio base station 1A, and the threshold setting unit 122B is based on a value unique to the radio base station 1B. Since the second random number generated for each communication channel is used, different priorities are assigned to the radio base station 1A and the radio base station 1B.
- the threshold setting unit 122A multiplies the first random number generated for each communication channel by the coefficient ⁇ for adjusting the difference between the channel assignment thresholds, and multiplies the first random number and the coefficient ⁇ .
- a result obtained by adding the result and a reference value serving as a reference for the channel assignment threshold is set as a channel assignment threshold corresponding to the first communication channel.
- the coefficient ⁇ the difference between channel assignment thresholds can be adjusted, and the degree of prioritization can be determined. Further, by using the reference value, the channel allocation threshold can be set to a practically appropriate value.
- the threshold setting unit 122A uses the first random number generated for each communication channel based on the value unique to the radio base station 1A, the subchannel number, and the time slot number, An allocation threshold is set for each communication channel.
- the threshold setting unit 122B uses the second random number generated for each communication channel based on the value unique to the radio base station 1B, the subchannel number, and the time slot number to set the second channel allocation threshold to the communication channel. Set every time. By using the subchannel number and the time slot number for generation of random numbers, the channel allocation threshold value for each communication channel can be made different more reliably.
- the threshold setting unit 122A is provided in the radio base station 1A and the threshold setting unit 122B is provided in the radio base station 1B.
- the threshold setting unit 122A and the threshold setting unit 122B are included in other devices. It is also possible to provide it.
- a threshold setting unit 122A and a threshold setting unit 122B may be provided in the server 4 (server device) as shown in FIG.
- the server 4 is connected to the radio base station 1A and the radio base station 1B via a wired communication network, and manages the radio base station 1A and the radio base station 1B.
- step S3 an example of setting the channel allocation threshold value by the processing flow of FIG. 5 has been described.
- step S3 when a favorable result is obtained in step S3, the processes in steps S4 and S5 are omitted. Also good.
- the channel assignment threshold value may be set by switching.
- the wireless communication system 10 has a configuration based on the next generation PHS.
- the wireless communication system 10 is not limited to the next generation PHS.
- a CSMA / CA Carrier Sense Multiple Access / Collision Avoidance
- the present invention is applicable.
- the present invention may be applied to a wireless LAN (IEEE802.11) system or a conventional PHS.
- the present invention can be similarly applied to a wireless communication system that employs LTE (Long Term Evolution), which is a standard established by 3GPP (Third Generation Partnership Project).
- LTE Long Term Evolution
- 3GPP Third Generation Partnership Project
- the wireless communication system, the wireless base station, and the threshold setting method according to the present invention can assign a plurality of communication channels to wireless terminals, and perform channel assignment using carrier sense.
- the communication capacity and the communication quality in the base station are guaranteed, and the fairness between the radio base stations can be ensured, which is useful as a communication system.
Abstract
Description
このような無線通信システムによれば、第1閾値設定部が第1チャネル割当閾値を通信チャネル毎に設定することにより、割り当て優先順位の高い通信チャネルと、割り当て優先順位の低い通信チャネルとが定義される。
図1は、本実施形態に係る無線通信システム10の全体概略構成図である。
次に、(2.1)無線基地局1Aの構成、(2.2)無線基地局1Bの構成について説明する。
図2(a)は、無線基地局1Aの構成を示す機能ブロック図である。図2(a)に示すように、無線基地局1Aは、アンテナ部101A、無線通信部110A、制御部120A、有線通信部130Aおよび記憶部140Aを有する。
図2(b)は、無線基地局1Bの構成を示す機能ブロック図である。ここでは、無線基地局1Bと重複する説明については省略する。
次に、図3および図4を用いて、無線基地局1Aおよび無線基地局1Bの概略動作について説明する。
このように、図4の例では、同一サブチャネル且つ同一時間スロットである通信チャネルおよび通信チャネルにおいて、一方の通信チャネルのチャネル割当閾値が高く設定され、他方の通信チャネルのチャネル割当閾値が低く設定されている。チャネル割当閾値が高いほど、被干渉レベルがチャネル割当閾値を下回る可能性が高くなるため、割り当て優先順位が高くなる。
図5は、無線基地局1Aの詳細動作、具体的には、第1チャネル割当閾値の設定方法の詳細を示すフローチャートである。無線基地局1Bにおいても図5の処理フローが実行される。
以上説明したように、無線通信システム10によれば、閾値設定部122Aが第1チャネル割当閾値を通信チャネル毎に設定することにより、割り当て優先順位の高い通信チャネルと、割り当て優先順位の低い通信チャネルとが定義される。同様に、閾値設定部122Bが第2チャネル割当閾値を通信チャネル毎に設定することにより、割り当て優先順位の高い通信チャネルと、割り当て優先順位の低い通信チャネルとが定義される。
上記のように、本発明は実施形態によって記載したが、この開示の一部をなす論述及び図面はこの発明を限定するものであると理解すべきではない。この開示から当業者には様々な代替実施形態、実施例及び運用技術が明らかとなる。
Claims (9)
- 第1無線端末に対し、所定周波数帯域内にある複数の通信チャネルのうちの被干渉レベルがチャネル割当閾値よりも低い第1低干渉通信チャネルを割り当てる第1無線基地局と、
第2無線端末に対し、前記所定周波数帯域内にある複数の前記通信チャネルのうちの被干渉レベルがチャネル割当閾値よりも低い第2低干渉通信チャネルを割り当てる第2無線基地局と
を備える無線通信システムであって、
前記第1低干渉通信チャネルを決定するためのチャネル割当閾値である第1チャネル割当閾値と、前記第2低干渉通信チャネルを決定するためのチャネル割当閾値である第2チャネル割当閾値とは、異なることを特徴とする無線通信システム。 - 前記第1チャネル割当閾値を設定する第1閾値設定部と、
前記第2チャネル割当閾値を設定する第2閾値設定部と
を備え、
前記第1閾値設定部は、前記第1無線基地局に固有の値を基に発生させた第1乱数を用いて、前記第1チャネル割当閾値を前記通信チャネル毎に設定し、
前記第2閾値設定部は、前記第2無線基地局に固有の値を基に発生させた第2乱数を用いて、前記第2チャネル割当閾値を前記通信チャネル毎に設定する請求項1に記載の無線通信システム。 - 前記第1閾値設定部は、
前記通信チャネル毎に発生させた前記第1乱数と、前記第1チャネル割当閾値間の差分を調整するための所定係数とを乗算し、
前記第1乱数と前記所定係数との乗算結果と、前記チャネル割当閾値の基準となる基準値とを加算した結果を、前記通信チャネルに対応する前記第1チャネル割当閾値として設定し、
前記第2閾値設定部は、
前記通信チャネル毎に発生させた前記第2乱数と、前記所定係数とを乗算し、
前記第2乱数と前記所定係数との乗算結果と、前記基準値とを加算した結果を、前記通信チャネルに対応する前記第2チャネル割当閾値として設定する請求項2に記載の無線通信システム。 - 前記第1閾値設定部は、前記第1無線基地局に設けられ、
前記第2閾値設定部は、前記第2無線基地局に設けられる請求項2または3に記載の無線通信システム。 - 前記第1無線基地局および前記第2無線基地局を管理するサーバ装置をさらに備え、
前記第1閾値設定部および前記第2閾値設定部は、前記サーバ装置に設けられる請求項2または3に記載の無線通信システム。 - 前記通信チャネルは、直交周波数分割多元接続方式および時分割多元接続方式に従って構成される請求項1に記載の無線通信システム。
- 前記第1閾値設定部は、前記第1無線基地局に固有の値に加え、前記直交周波数分割多元接続方式に応じたサブチャネル番号と、前記時分割多元接続方式に応じた時間スロット番号とを基に前記通信チャネル毎に発生させた前記第1乱数を用いて、前記第1チャネル割当閾値を前記通信チャネル毎に設定し、
前記第2閾値設定部は、前記第2無線基地局に固有の値に加え、前記サブチャネル番号と前記時間スロット番号とを基に前記通信チャネル毎に発生させた前記第2乱数を用いて、前記第2チャネル割当閾値を前記通信チャネル毎に設定する請求項6に記載の無線通信システム。 - 複数の通信チャネルにおける被干渉レベルを測定し、測定した被干渉レベルがチャネル割当閾値よりも低い低干渉通信チャネルを無線端末に対し少なくとも1つ割り当てる無線基地局であって、
前記チャネル割当閾値を前記通信チャネルそれぞれについて設定する閾値設定部を備え、
前記閾値設定部は、前記無線基地局に固有の値を基に、前記チャネル割当閾値を前記通信チャネル毎に設定する無線基地局。 - 第1無線基地局が第1無線端末に対し、所定周波数帯域内にある複数の通信チャネルのうちの被干渉レベルがチャネル割当閾値よりも低い第1低干渉通信チャネルを割り当てるステップと、
第2無線基地局が第2無線端末に対し、前記所定周波数帯域内にある複数の前記通信チャネルのうちの被干渉レベルがチャネル割当閾値よりも低い第2低干渉通信チャネルを割り当てるステップと
を含み、前記チャネル割当閾値を設定する閾値設定方法であって、
前記第1低干渉通信チャネルを決定するためのチャネル割当閾値である第1チャネル割当閾値と、前記第2低干渉通信チャネルを決定するためのチャネル割当閾値である第2チャネル割当閾値とは、異なることを特徴とする閾値設定方法。
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