JP2009060179A - Communication device and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that channel release on the assumption of radio terminals in multi-carrier systems has not been conventionally considered at all. <P>SOLUTION: The communication device (100) performing communication using a time division multiple access system and an adaptive modulation system includes: a channel management part (120) which manages a plurality of communication channels; an acquisition part (130) which acquires power information and/or modulation information of the plurality of communication channels per communication channel; and a control part (140) which controls the communication channel management part so that at least one of communication channels of which the power information and/or modulation information acquired by the acquisition part don't meet a prescribed condition is selected and released. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication device and a communication method, and more particularly to a communication device and a communication method that use a session to which a plurality of communication channels are allocated, and a communication device that selects and releases a communication channel that can minimize communication efficiency as much as possible. It relates to a communication method.

  In a time division multiple access (TDMA) communication system, particularly in iBurst (registered trademark), with an increase in the amount of communication data exchanged between a base station and a terminal, A method of assigning a plurality of carriers at the same timing (see Non-Patent Document 1) is being studied. According to this, for example, a channel bandwidth of 20 MHz is divided into four and used as a carrier of 5 MHz (four carriers), and at the same timing, continuous communication channels for a maximum of four carriers are used. Can

  In such a multi-carrier environment, a situation occurs in which a plurality of communication channels assigned to the terminal must be released. For example, when a terminal to which a plurality of communication channels are assigned moves from the center of the coverage area of the base station to the edge, each communication is gradually performed as the distance between the base station and the terminal increases. The transmission power of the channel needs to be increased. However, since the terminal cannot transmit with power exceeding the “maximum transmission power per terminal” determined by the law or the performance of the terminal, when the distance between the base station and the terminal becomes long (typically Is near the edge of the cover area), and the “transmission power per communication channel” required for each communication channel is limited by the “maximum transmission power per terminal”. Therefore, the terminal cannot make maximum use of the capacity of each communication channel occupied, which also reduces the frequency utilization efficiency of the entire communication system.

However, in another conventional technique (see Patent Document 1), a channel to be released is selected as a channel for releasing a predetermined channel regardless of the communication state. Note that there is no room for channel selection when the wireless terminal handles one channel in the same time slot as in the conventional iBurst (registered trademark) system, that is, in the case of a single carrier.
Revised: Wireless broadband textbook (high-speed IP wireless), Takeshi Hattori, Masanobu Fujioka (edited), published by Impress R & D Japanese Patent Laid-Open No. 11-212946

  In the conventional method, channel release based on a multi-carrier wireless terminal is not considered at all. Therefore, when a predetermined channel is selected or randomly selected as a channel to be released, depending on the channel to be selected, there is a possibility that a demerit may occur for the wireless terminal (than when another channel is selected). . FIG. 2 shows a channel management table assigned to a session of a multicarrier wireless terminal. As shown in the figure, there are twelve channels up to channel ch0-11, and six of them (channels ch0, ch3-6, ch8, and ch9) are allocated to the radio terminals. In the upper part of each channel section in the figure, the modulation class of the channel is shown, and the lower part shows the transmission power (dBm). For example, when one channel of time slot 0 is released in the communication state as shown in FIG. 2, there are four choices of channels ch0, ch3, ch6, and ch9. There is.

In order to solve the above-described problems, the communication device according to the first invention provides:
A communication device (base station device, terminal device, etc.) that performs communication using a time division multiple access (TDMA) system,
A communication channel management unit that manages a plurality of communication channels assigned to a session between the counterpart communication device and the own device;
An acquisition unit that acquires power information and / or communication speed information (data throughput, etc.) of the plurality of communication channels for each communication channel;
A control unit that controls the communication channel management unit to select and release at least one of the communication channels in which the power information and / or communication speed information acquired by the acquisition unit does not satisfy a predetermined condition;
Have

The communication device according to the second invention is
A communication apparatus that performs communication using a time division multiple access (TDMA) scheme and an adaptive modulation scheme,
A communication channel management unit that manages a plurality of communication channels assigned to a session between the counterpart communication device and the own device;
An acquisition unit that acquires power information and / or modulation information (such as a modulation class) of the plurality of communication channels for each communication channel;
A control unit that controls the communication channel management unit so as to select and release at least one communication channel in which the power information and / or modulation information acquired by the acquisition unit does not satisfy a predetermined condition;
Have

  In addition, when the communication device described above is a communication terminal, the communication device preferably transmits a channel release request signal including the number of the selected communication channel to the base station device that is the counterpart communication device. is there.

The communication device according to the third invention is
When there are a plurality of communication channels having power information that does not satisfy the predetermined condition, the control unit
Based on the communication speed information or the modulation information, the communication channel management unit is controlled to select and release at least one of a plurality of communication channels having the less-than-less power information.
It is characterized by that.

The communication device
A communication type acquisition unit that acquires (understands) the communication type of the session;
The communication channel management unit
It is preferable to control the communication channel management unit so as to determine whether or not to make a selection based on the communication speed information or the modulation information according to the communication type acquired by the communication type acquisition unit.

In addition, the control unit
When the communication type is voice communication, it is preferable to control the communication channel management unit so as not to perform selection based on the communication speed information or the modulation information.

  As described above, the solution of the present invention has been described as an apparatus. However, the present invention can be realized as a method, a program, and a storage medium storing the program, which are substantially equivalent to these. It should be understood that these are also included.

For example, according to another embodiment in which the present invention is implemented as a method, the communication method according to the fourth invention is:
A communication method for performing communication between communication devices using a time division multiple access (TDMA) method,
Managing a plurality of communication channels assigned to a session between communication devices;
Obtaining power information and / or communication speed information (such as data throughput) of the plurality of communication channels for each communication channel; and
Controlling to select and release at least one of the communication channels in which the power information and / or communication speed information acquired by the acquiring step does not satisfy a predetermined condition;
Have

A communication method according to the fifth invention is
A communication method for performing communication between communication devices using a time division multiple access (TDMA) method and an adaptive modulation method,
Managing a plurality of communication channels assigned to a session between communication devices;
Obtaining power information and / or modulation information (such as modulation class) of the plurality of communication channels for each communication channel; and
Controlling to select and release at least one communication channel in which the power information and / or modulation information acquired by the acquiring step does not satisfy a predetermined condition;
Have

  In each step described above, a processor (CPU, DSP, MPU, etc.) mounted on each communication device, communication means (transmitter, receiver) such as an RF circuit, and a storage device are used as necessary.

  According to the present invention, when a part of communication channels is released from a plurality of communication channels, the optimum communication according to the communication environment of the communication devices (that is, the distance between devices, radio wave interference status, frequency diversity). It becomes possible to select a channel. Therefore, it is possible to provide an optimal communication channel assignment environment for both the terminal and the entire communication system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the present invention can be realized regardless of a base station or a terminal. Several communication systems using a plurality of communication channels are conceivable. In this embodiment, a communication system using a time division multiple access (TDMA) system and an adaptive modulation system is used. FIG. 1 is a block diagram showing a basic configuration of a wireless communication apparatus according to an embodiment of the present invention. As shown in FIG. 1, the wireless communication apparatus 100 includes a communication unit 110, a channel management unit 120, a channel information acquisition unit 130, a control unit 140, a storage unit 150, and an antenna ANT.

  The control unit 140 controls the entire apparatus and controls other units. The communication unit 110 performs transmission / reception with the counterpart communication device via the antenna ANT. The channel management unit 120 manages a plurality of communication channels assigned to a session established between the counterpart communication device and the own device. The channel management unit 120 records the modulation class and the transmission power for each communication channel in the channel management table as shown in FIG. 2, for example, at least while establishing a session with the counterpart communication device. When the wireless communication device 100 is a base station device, the channel management unit 120, upon receiving a connection request from a communication terminal that is a counterpart communication device, the requesting communication terminal (that is, the requesting communication terminal and its own device) Function as a channel allocation unit that allocates a plurality of communication channels to a session established between The channel information acquisition unit 130 acquires and acquires power information and modulation information (such as a modulation class) of a plurality of communication channels for each communication channel and stores them in the channel management table of the storage unit 150. Since wireless communication apparatus 100 uses an adaptive modulation scheme, modulation information and transmission power may vary from frame to frame and from channel to channel. Therefore, the channel information acquisition unit 130 acquires power information and modulation information (modulation class) for each frame and each channel, and updates (maintenance) the channel management table. The control unit 140 refers to the channel management table in the storage unit 150, and selects the channel management unit 120 so as to select and release at least one communication channel whose power information and / or modulation information does not satisfy a predetermined condition. Control.

As described above, the control unit 140 determines to release the communication channel for some reason. For example, when a wireless terminal communicates with a base station under the rated transmission power, the transmission power must be increased by releasing some communication channels due to the movement of the terminal and the deterioration of the propagation environment. In some cases, it is decided to release the communication channel. By applying the present invention, the following advantages can be obtained.
・ Improvement of data throughput (communication speed) ・ Reduction of power consumption (that is, longer battery life by reducing transmission power)
・ Improved noise resistance ・ Improved frequency usage efficiency

The wireless communication apparatus 100 evaluates the channel under communication for the following three points according to an algorithm for determining a preset release channel, and determines a communication channel to be released.
・ Data throughput (communication speed)
・ Radio terminal side (uplink) transmission power ・ Used carrier (frequency band)

  The table below is a correspondence table showing the relationship between the modulation class (mod class) used by the wireless communication apparatus 100 and the throughput (communication speed). The storage unit 150 further stores this correspondence table.

  The channel ch0 of the carrier A in FIG. 2 is the modulation class 7, and it can be seen that the throughput of the modulation class 7 is 427.2 kbps by referring to Table 1. Similarly, it can be seen that channel 3 of carrier B and channel ch9 of carrier D are modulation class 6 and their throughput is 345.6 kbps. Assume that it is necessary to release one channel of time slot 0 in the communication environment of each communication channel of FIG. In such a case, for example, when channel ch0 of carrier A (class 7: 427.2 kbps) is released by random selection, channel ch3 of carrier B or channel ch9 of carrier D (class 6: 345.6 kbps) is used. Inconveniences such as lowering the throughput than in the case of being released occur. The present invention eliminates the disadvantages of the release channel selection as described above by using the following release channel selection algorithm.

  An outline of the release channel selection algorithm will be described. In the time slot to be released or when it should be released regardless of the time slot, the information is compared in the following order with respect to the channel during communication in all the time slots. However, this order is an example, and it should be noted that the order can be changed as long as there is no logical contradiction, such as selection based on transmission power first.

<Selection based on data throughput (communication speed)>
The one having the smallest modulation class (data throughput) is selected. When the modulation class is the same, the wireless terminal transmission power is compared. In this way, by selecting a data throughput that is low (that is, a frequency use efficiency is low), it is possible to suppress a decrease in data throughput and simultaneously suppress interference waves to other communication apparatuses.

<Selection based on transmission power>
The wireless terminal transmission power (power) having the highest power is selected. If there is the same thing, check the information about the carrier. By selecting one having a large transmission power, power consumption can be suppressed and a communication channel with high power efficiency, that is, a communication channel with a small interference wave can be left.

<Selection based on carrier information>
When a plurality of channels are release candidates by the above selection, it is checked whether the release candidate channels are used in other time slots, and carriers used in other time slots are also checked. If so, make it a candidate for the release channel. By leaving a plurality of carriers as much as possible, noise resistance when interference with a specific carrier occurs is increased. For example, if the used carrier is biased, it will be affected in all time slots if strong interference occurs with that carrier, but it will be affected by dispersing the carriers as much as possible (ie, by increasing the frequency diversity). Can be minimized.

<Connection time>
If a plurality of channels are still release candidates due to the selection described above, the communication channel with the longest connection time is selected from the release candidate channels. When a base station is congested, a channel with a long connection time may be subject to release (such as Fairness Mac of iBurst (registered trademark) system). It is beneficial for wireless terminals to keep them.

  The release channel selection algorithm described above is specifically shown with reference to a flowchart. FIG. 3 is a flowchart of a communication method (release channel selection algorithm) according to an embodiment of the present invention. As shown in the figure, when a situation requiring channel release occurs, the data throughput (or modulation class) is lowest in step S11 by referring to the management table of FIG. 2 and the table of Table 1. Ask for a channel. Next, in step S12, it is determined whether or not there are two or more target channels obtained in step S11. When the condition of step S12 is not satisfied (only one channel), the process proceeds to step S17, the corresponding channel is set as a release target, and the process ends. When the condition of step S12 is satisfied (the number of channels is two or more), the management table of FIG. 2 is referred to, and the channel having the highest transmission power (power) is obtained from the two or more channels.

  Next, in step S14, it is determined whether there are two or more target channels obtained in step S13. When the condition of step S14 is not satisfied (only one channel), the process proceeds to step S17, the corresponding channel is set as a release target, and the process ends. If the condition of step S14 is satisfied (the number of channels is 2 or more), it is checked whether or not the obtained 2 or more channels (that is, release candidate channels) are also used in other time slots. If there is a carrier that is also used in the time slot, find it. In step S16, it is determined whether or not there are two or more target channels obtained in step S15. When the condition of step S16 is not satisfied (only one channel), the process proceeds to step S17, the corresponding channel is set as a release target, and the process ends. If the condition of step S16 is satisfied (two or more channels), the channel having the longest connection time (duration from the time of allocation) is set as the release target among the two or more channels obtained. Finish the process.

For example, when releasing the channel of time slot 0 in the communication situation as shown in FIG.
1. Carriers B and D are selected from the viewpoint of data throughput, and since both transmission powers are the same, carrier information is checked.
2. When the carrier information is checked, carrier B is also used in time slot 1, but carrier D is not used in all time slots, so carrier B is selected as the target for the release channel.
In this way, it is possible to release an optimal communication channel.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each unit, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined or divided into one. It is.

  The above-described embodiment can be applied not only to the iBurst (registered trademark) system but also to many multi-carrier wireless systems, and can be extended by software, so that it can be applied to conventional systems, communication terminals, and base stations. It can be easily implemented.

It is a block diagram which shows the basic composition of the radio | wireless communication apparatus by one embodiment of this invention. It is a figure which shows the channel management table allocated to the session of the radio | wireless terminal of a multicarrier system. , Is a flowchart of a communication method (release channel selection algorithm) according to an embodiment of the present invention;

Explanation of symbols

100 wireless communication apparatus 110 communication unit 120 channel management unit 130 channel information acquisition unit 140 control unit 150 storage unit ANT antenna
ch0-11 channel

Claims (5)

In a communication device that performs communication using a time division multiple access method,
A communication channel management unit that manages a plurality of communication channels assigned to a session between the counterpart communication device and the own device;
An acquisition unit that acquires power information and / or communication speed information of the plurality of communication channels for each communication channel;
A control unit that controls the communication channel management unit to select and release at least one of the communication channels in which the power information and / or communication speed information acquired by the acquisition unit does not satisfy a predetermined condition;
A communication device. In a communication apparatus that performs communication using a time division multiple access method and an adaptive modulation method,
A communication channel management unit that manages a plurality of communication channels assigned to a session between the partner communication device and the own device;
An acquisition unit that acquires power information and / or modulation information of the plurality of communication channels for each communication channel;
A control unit that controls the communication channel management unit to select and release at least one of the communication channels in which the power information and / or modulation information acquired by the acquisition unit does not satisfy a predetermined condition;
A communication device. The communication device according to claim 1 or 2,
When there are a plurality of communication channels having power information that does not satisfy the predetermined condition, the control unit
Based on the communication speed information or the modulation information, the communication channel management unit is controlled to select and release at least one of a plurality of communication channels having the less-than-less power information.
A communication device. In a communication method for performing communication between communication devices using a time division multiple access method,
Managing a plurality of communication channels assigned to a session between communication devices;
Obtaining power information and / or communication speed information of the plurality of communication channels for each communication channel; and
Controlling to select and release at least one of the communication channels in which the power information and / or communication speed information acquired by the acquiring step does not satisfy a predetermined condition;
A communication method. In a communication method of performing communication between communication devices using a time division multiple access method and an adaptive modulation method,
Managing a plurality of communication channels assigned to a session between communication devices;
Obtaining power information and / or modulation information of the plurality of communication channels for each communication channel; and
Controlling to select and release at least one communication channel in which the power information and / or modulation information acquired by the acquiring step does not satisfy a predetermined condition;
A communication method.

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