JP2008211351A - Communication method and radio communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce unnecessary power consumption, especially, on a reception side by increasing the frequency efficiency of the whole system when data to be sent to a radio terminal having a channel added by channel aggregation decrease. <P>SOLUTION: A radio communication device which uses a time-division multiple access/time-division duplex operation system having a plurality of time slots for communication with the radio terminal and allocates a plurality of pairs of uplink-side and downlink-side channels set to the time slots to the radio terminal has a downlink flow rate monitoring unit which acquires data traffic amounts of the downlink-side channels included in the plurality of allocated pairs of channels, and a downlink channel state control unit which stops transmission of at least one downlink-side channel included in the plurality of pairs of channels allocated to the radio terminal according to the acquired data traffic amounts of the downlink-side channels. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication method and a wireless communication apparatus.

In a communication system using TDMA-TDD (Time Division Multiple Access / Time Division Duplex) and an adaptive array antenna, the antenna weight of the downlink signal based on the uplink signal (weighting of each antenna element constituting the antenna array) The prior art for estimating the frequency: "Downlink transmission in a wireless data communication system having a base station having a smart antenna system" (see Patent Document 1) has been developed and put into practical use. This is because the channel (slot) in the uplink direction from the radio terminal to the base station and the channel (slot) in the downlink direction from the base station to the radio terminal use the same frequency, and the channel transmission path itself This technology is based on the assumption that the propagation characteristics are continuous. Further, in this prior art, since the antenna weight of the downlink signal to be emitted is determined based on the received uplink signal, the number of downlink channels and the number of uplink channels are made the same. There is a need. Therefore, the base station assigns a channel pair (time slot pair) composed of an uplink-side channel and a downlink-side channel as one unit to one radio terminal. In order to cope with the case where the amount of data to be transmitted cannot be processed by only one channel (slot) per one direction (downlink or uplink) allocated in this way, a plurality of channels are arranged in one direction. A channel aggregation technique that bundles and assigns to one wireless terminal has been proposed. This makes it possible to use applications such as high-quality videophone and high-speed reception / transmission such as video / music data download that transmit a large amount of data that could not be transmitted in the band of one channel (slot). It became possible.
Special table 2004-510391 gazette

  In the channel set and assigned in this way, the same fixed amount of data may flow in both the downlink and uplink directions. However, in the case of a client / server communication model, the client is up. In many cases, a small amount of data (a request) is transmitted in the link direction, and the server transmits a large amount of data (response data for the request) in the downlink direction. Such request transmission by the client and response data transmission by the server do not always occur, and there are many patterns that occur intermittently. That is, the amount of data to be transmitted in the downlink direction often increases or decreases significantly.

  In addition, in applications that consume a large band such as videophones, there are cases where a communication terminal serving as a client transmits a large amount of data such as images and voices in the uplink direction. In this case, in order to cope with the channel (slot) in the uplink direction transmitting a large amount of data as described above, the channel is added by the channel aggregate. On the other hand, the channel in the downlink direction is usually allocated a band larger than the band in the uplink direction, and the band of the channel allocated first may be sufficient, and was added in the channel aggregate. The channel bandwidth in the downlink direction is rarely used and is wasted.

  For these various cases, when applying the above-mentioned channel aggregation technology, regardless of the downlink direction or uplink direction, the channel aggregation depends on the large amount of data to be transmitted, the application to be used, QoS, etc. Depending on the technology, a plurality of channels (slots) are assigned to one direction for a session with the communication terminal. However, as described above, there is an imbalance in the amount of data in the downlink direction and the uplink direction, and in particular, in a channel added in the downlink direction, which usually has a large bandwidth, all the bandwidth cannot be consumed and wasted. There is a case. Even in such a case, the base station emits radio waves using a channel added in the downlink direction, even though there is no data to be transmitted.

  On the other hand, if the channel additionally set by the channel aggregation technique is released when the data amount is reduced, there are the following problems. For example, when a channel is additionally set by the channel aggregation technique based on an increase in the flow rate, in the subsequent communication, a large amount of data often flows again and again. In a situation where resources to be allocated (ie, channels / slots) are scarce as in a wireless communication system and many wireless terminals compete for resources, a channel may be allocated when a large amount of data flows again. There is no guarantee and releasing the reserved resources is extremely inconvenient.

  Furthermore, when spatial multiplexing is performed using spatial multiplexing multiple access (SDMA), desired waves in the downlink direction for any wireless terminal share the same traffic channel and other spatial multiplexing wireless terminals of the same base station And, since it becomes an interference wave in reception of radio terminals of different base stations, the effective frequency use efficiency of the entire system is lowered. When a wireless terminal that is waiting for a radio wave receives a radio wave that is unnecessary for such a radio terminal and that is transmitted to another radio terminal, the reception of the unnecessary radio wave causes LNA (Low Noise) to be received. Amp) etc. consumes current, which consumes wasted power and causes battery saving problems. When there is a lot of data traffic from the wireless terminal to the base station (in the uplink direction), and “channel aggregate” is performed in which a plurality of channels are bundled into one and assigned to the wireless terminal, conversely, from the base station to the wireless terminal Considering only the direction from the base station to the wireless terminal when there is little data traffic, it is composed of a bidirectional channel aggregate, that is, a channel on the uplink side and a channel on the downlink side, even when channel aggregation is not originally required. It was necessary to perform channel assignment in units of channel pairs.

  By the downlink and uplink bidirectional channel aggregates as described above, unnecessary radio waves are emitted from the base station to the wireless terminal, and the wireless terminal communicating with the base station in the same spatial multiplexing and the peripheral Unwanted interference waves (interference waves) were given to wireless terminals on the same frequency communicating with other base stations. On the other hand, on the wireless terminal side, radio waves unnecessary for the wireless terminal are received, and battery power is consumed using wasted power.

  Therefore, the present invention provides a plurality of data allocated to the wireless terminal while securing the added channel when data to be flowed toward the wireless terminal having the channel added by the channel aggregate decreases. By controlling the usage state of at least one of the channels on the downlink side (typically, stopping transmission), the frequency efficiency of the entire system is increased, and in particular on the reception side. The purpose is to reduce power consumption.

In order to solve the above-described problems, a method for controlling a wireless communication apparatus according to the first invention is:
Channels and downlinks on the uplink side set in the plurality of time slots (by channel aggregate) using a time division multiple access / time division duplex method having a plurality of time slots in communication with a wireless terminal A plurality of channel pairs (time slot pairs) composed of channels on the side, the communication method of the wireless communication device assigning to the wireless terminal,
An acquisition step of acquiring a data traffic amount of a channel on a downlink side (from a wireless communication device to a wireless terminal) included in the plurality of assigned channel pairs;
A control step of controlling a use state of at least one downlink side channel included in a plurality of channel pairs allocated to the wireless terminal according to the acquired data traffic amount of the downlink side channel;
Have

A control method for a wireless communication apparatus according to the second invention is as follows:
Using the calculation means (processor such as CPU), the data traffic volume of the downlink side channel acquired by the acquisition step, and the downlink side channels included in the plurality of channel pairs allocated to the wireless terminal, A comparison step that compares a threshold defined according to the number of channels on the downlink side that are in use (in operation not down) (typically the number of channels in operation and bandwidth);
The control step comprises:
When the amount of data traffic on the downlink side channel is smaller than the threshold value by the comparison step, the usage state of at least one downlink side channel included in a plurality of channel pairs assigned to the wireless terminal is controlled.
It is characterized by that.

A method for controlling a wireless communication device according to a third aspect of the invention includes:
The control step comprises:
At least a part of transmission using at least one downlink side channel included in a plurality of channel pairs assigned to the wireless terminal (for example, part of the time interval in one slot of the channel or the whole transmission is stopped) Or by intermittently stopping slots at intervals of one or more frames) to control the usage state (that is, transmission state and antenna weight) of the at least one channel.
It is characterized by that.

According to a fourth aspect of the present invention, there is provided a wireless communication device control method comprising:
A notification step of notifying the wireless terminal that the usage state of the at least one downlink side channel is controlled before executing the control step;
A reception step of receiving a response (for example, control permission or stop permission) permitting the control from the wireless terminal notified by the notification step;
The control step comprises:
Controlling usage of the at least one downlink side channel after receiving the response;
It is characterized by that.

According to a fifth aspect of the present invention, there is provided a wireless communication device control method comprising:
When the use state of the at least one channel is controlled by the control step, the use state of the at least one channel on the downlink side is returned to a normal state according to the amount of data traffic on the downlink. (I.e., resume normal transmission control)
Is further included.

According to a sixth aspect of the present invention, there is provided a wireless communication device control method comprising:
Each of the plurality of time slots is spatially multiplexed.
It is characterized by that.

  As described above, the solution of the present invention has been described as a method. However, the present invention can also be realized as a device (wireless communication device such as a base station) substantially equivalent to these, a program, and a storage medium storing the program. It should be understood that these are included within the scope of the present invention.

For example, a wireless communication device according to a seventh aspect of the present invention that realizes the present invention as a device is:
Channels and downlinks on the uplink side set in the plurality of time slots (by channel aggregate) using a time division multiple access / time division duplex method having a plurality of time slots in communication with a wireless terminal A wireless communication device that assigns a plurality of channel pairs (time slot pairs) composed of channels on the side to the wireless terminal,
(With a channel aggregate, a channel allocation management unit that allocates a plurality of channel pairs (uplink and downlink time slot pairs) consisting of an uplink channel and a downlink channel to the wireless terminal)
A downlink flow rate monitoring unit for acquiring a data traffic amount of a channel on a downlink side (from a wireless communication device to a wireless terminal) included in the plurality of assigned channel pairs;
A downlink channel transmission state control unit that controls a transmission state of at least one downlink side channel included in a plurality of channel pairs allocated to the wireless terminal according to the acquired data traffic amount of the downlink side channel When,
Have

  According to the present invention, when data to be flowed toward a wireless terminal having a channel additionally assigned by a channel aggregate decreases, a plurality of data assigned to the wireless terminal are secured while securing the added channel. By controlling the transmission state of at least a part of at least one of the channels on the downlink side (typically stopping transmission of the entire channel), the frequency efficiency of the entire system is increased, in particular, It is possible to reduce wasteful power consumption on the receiving terminal side that receives the downlink transmission.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Prior to the description of the principle and configuration of the present invention, a wireless system, a time slot configuration, and the like targeted by the present invention will be described.

<Wireless system>
Examples of communication systems compliant with the wireless communication standard using the TDMA-TDD communication method targeted by the present invention include PHS (Personal Handyphone System) and iBurst (registered trademark) systems, each of which is “ARIB STD”. -28 (ARIB) ”and“ High Capacity-Spatial Division Multiple Access (HC-SDMA) WTSC-2005-032 (ATIS / ANSI) ”.

<Adaptive antenna array>
An adaptive antenna array having a plurality of antenna elements is typically implemented in a base station. When implemented in the base station, it is possible to suppress the interference wave included in the uplink reception wave and to estimate the arrival path of the desired wave by deriving the antenna weight (weight) by reception. The adaptive antenna array also sets the transmit antenna weight so that the SINR (Signal to Noise Ratio) is maximized for radio terminals that estimate the weight, and the signal is suppressed otherwise. As a result, it is possible to dramatically increase the link capacity while ensuring the communication quality. As an example of actual operation, there is an iBurst (registered trademark) system that conforms to “High Capacity-Spatial Division Multiple Access (HC-SDMA) WTSC-2005-032 (ATIS / ANSI)”.

<TDMA-TDD and antenna array>
In the TDMA-TDD scheme, the same frequency is used for the channel in the uplink direction from the radio terminal to the base station and the channel in the downlink direction from the base station to the radio terminal. By using the same frequency in this way, it is possible to theoretically use the antenna weight obtained by reception for transmission, so that there is an advantage that it is easy to improve the performance using the antenna array. In other words, in the same frequency band in a short period, it is assumed that there is continuity between the transmission path itself and the propagation characteristics in the propagation path between an arbitrary point and other arbitrary points, and the transmission path obtained by uplink reception Assume that the antenna superposition (weight) coefficient that matches the above can be used for downlink transmission. In general, this assumption has sufficient practicality when the time difference (time interval) between the reception signal and transmission signal used for estimation is short and the moving speed of the wireless terminal is slow.

<How to obtain antenna weight>
The Winner solution is well known as an antenna weight, and the method for obtaining the Winner solution is to minimize the mean square error (MSE) between the training signal (reference signal) and the received signal from the receiving antenna array. It is known that sequential updating by an algorithm is often used. As this adaptive algorithm, the LMS (Least Mean Square) algorithm is often used. The LMS algorithm requires a known training signal, which is typically applied by the wireless terminal to the beginning or end of the uplink signal, or both, with a known training signal pattern shared between the base station and the wireless terminal. In a base station, a method using a known pattern as a training signal is often used.

<Radio resource allocation method>
In a communication method using TDMA-TDD, radio resources used for a traffic channel are determined by a TDMA-TDD slot and a frequency channel. In other words, when 3 times are multiplexed in time by TDMA-TDD and 4 frequency channels (carriers) can be used, 12 (= 3 spatial multiplexing × 4 carriers) traffic channels can be prepared. However, the TDMA-TDD scheme requires a channel for synchronization with the base station, and one or more radio resources are used as, for example, a broadcast information channel and cannot be used as a traffic channel in many cases. Among these traffic channels, a traffic channel that is unused can be used. As a method for determining the unused state, the radio terminal side measures the interference wave of the uplink radio channel resource, and if the measured RSSI (Received Signal Strength Indicator) is less than or equal to the threshold value, determines that the channel is not used. There is a method of firing the start request signal. It is known that the use of the slotted ALOHA algorithm as specified in ARIB STD-28 (ARIB) increases the possibility of smooth re-resource selection during a collision.

  When spatial multiplexing using an antenna array is implemented on the base station side, the traffic channel can be doubled by the number of spatial multiplexing by management on the base station side. In “High Capacity-Spatial Division Multiple Access (HC-SDMA) WTSC- 2005-032 (ATIS / ANSI)”, a signal for establishing a traffic channel and a training signal for each traffic channel with 3 spatial multiplexing of traffic channels. Spatial multiplexing is realized by dividing patterns.

<Restrictions on base station placement>
In the spatial multiplexing described above, in the case of a single base station, it is not necessary to consider the influence of radio waves emitted by other base stations and wireless terminals connected to other base stations. However, when there are a plurality of base stations, radio waves emitted by other base stations and wireless terminals connected to other base stations become interference waves on the same traffic channel, which increases frame reception errors. Cause. Therefore, when placing base stations, the base stations should be sufficiently separated from each other, the radio waves from the base stations should have horizontal directivity, the antenna should have a chilled angle to reduce the influence from adjacent base stations, etc. Generally, the following method is taken.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 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 the figure, the wireless communication device 100 includes a control unit 110 that controls the entire device, a channel assignment management unit 120, a downlink flow rate monitoring unit 130, a reception unit 140, a transmission unit 150, and a downlink channel transmission state control unit. (Downlink channel transmission stop / start control unit) 160, storage unit 170, and adaptive array antenna AA. When there is data to be transmitted to a communication partner wireless terminal having a session with the own device, control unit 110 controls transmission unit 150 to transmit the data via adaptive array antenna AA. The adaptive array antenna AA has a plurality of antenna elements, and each antenna element is a radio wave corresponding to the antenna weight (weighting) calculated for each antenna element based on the received signal for each antenna element received by the receiving unit 140. (This antenna weight will be described in detail later). The channel allocation management unit 120 adds a channel aggregation technique to a wireless terminal when any element such as flow rate or QoS satisfies a channel addition criterion in a session between the own apparatus and a wireless terminal of a communication partner using a channel aggregation technique. Channels are allocated, and the channel allocation status is stored in the channel allocation table TB1 in the storage unit 170. The storage unit 170 further includes a reference flow rate table TB2, in which the maximum transmission flow rate and the reference flow rate (threshold value) corresponding to the number of downlink side channels are stored. For example, the following table.

  The downlink flow rate monitoring unit 130 acquires the data traffic volume of the downlink side channel included in the assigned plurality of channel pairs. The downlink channel transmission state control unit 160, when the acquired data traffic volume of the downlink side channel becomes less than the reference flow rate of the corresponding number of channels in Table 1 (TB2), The transmission state of at least one downlink side channel included in the channel pair is controlled (typically, transmission is stopped). For example, when 4 downlink channels are allocated in the channel aggregate, when the downlink flow rate of the session is less than the reference flow rate 900 kbps for 4 channels, one channel is stopped, Downlink data is transmitted using only three channels. Then, the transmission of the channel stopped when the downlink flow rate becomes equal to or higher than the reference flow rate 900 kbps is resumed. In addition, when four downlink channels are allocated in the channel aggregate, when one channel is stopped and transmission is performed with three channels as described above, the downlink flow rate of the session is When the reference flow rate is less than 600 kbps for three channels, another channel (two in total) may be stopped and downlink data may be transmitted using only two channels. In this way, the power consumption of the wireless terminal that receives the downlink signal can be reduced by stopping or restarting the transmission on the downlink side channel allocated by the channel aggregate according to the downlink flow rate. Further, it is possible to reduce interference with another channel (slot) that is a slot having the same timing as the channel and that is spatially multiplexed using the same carrier. Furthermore, the wireless terminal can keep a channel allocated additionally based on the channel aggregation technique, and can cope with the fluctuation of the downlink flow rate in the subsequent communication. That is, according to this method, since the channel is not released, the channel is re-established only when the downlink data exceeds the threshold (reference flow rate) defined according to the number of transmission state channels at that time. There is an advantage that the transmission of the channel on the downlink side can be resumed immediately without the need for assignment. The threshold value (reference flow rate) can be determined arbitrarily according to the maximum transmission flow rate / speed of the channel (slot), and a hysteresis width is provided between the transmission stop threshold value and the transmission restart threshold value, and the determination operation chatters. May be prevented.

  Next, the present invention will be described by specifically applying the present invention to a base station (apparatus) that is a typical example of a radio communication apparatus having an adaptive array antenna and a radio terminal that is a communication partner of the base station. FIG. 2 is a diagram illustrating a configuration example of a wireless communication system according to an embodiment of the present invention. The base stations BS1 and BS2 have an adaptive array antenna (not shown) composed of six antenna elements, and establish a digital radio path with the radio terminals TM1 and TM2. As a channel model, it is assumed that a large number of scatterers are distributed between the base station and the wireless terminal, and a frequency non-selective multiple propagation path is formed. Since the wireless terminal is movable, the multiple propagation paths between the wireless terminal and the base station have different Doppler frequencies. The wireless terminal and the base station communicate with each other by TDMA-TDD digital wireless communication.

  FIG. 3 shows a frame format example of TDMA-TDD. As shown in the figure, a TDMA-TDD frame has a slot of asymmetric length in uplink and downlink in TDMA 3 multiplexing. One frame is multiplexed three times and is divided into three slots for both uplink and downlink. In the uplink slot, one time distribution is 545 μsec, and three uplink slots are continuous. A guard time of 10 μsec between uplink and downlink is provided behind the uplink slot, and a group of downlink slots follows.

  In the downlink slot, one time distribution is 1090 μsec, which is twice the time distribution of the uplink slot. Similarly to the uplink slot, the downlink slot has a configuration in which three are continuous. The first uplink slot and the first downlink slot are paired to form one bidirectional channel. The same goes for the second and third uplink / downlink slot pairs. FIG. 4 shows the arrangement of carriers (frequencies) used in this embodiment. As shown in the figure, a continuous frequency of 625 KHz is taken as one unit, which is 4 units.

  Next, radio resources will be described. The TDMA-TDD frame has 5 msec as 1 frame and is multiplexed 3 times. The frequency channel has a width of 625 KHz and can use a frequency channel for four carriers and occupies 2.5 MHz. Carriers 0 to 3 are set in ascending order of frequency, and 12 channels are formed by combining time slots 1 to 3. Here, the combination of carrier 0 and slot 1 is 1ch (channel), and channel numbers are assigned as shown in Table 2. 1ch is reserved for the broadcast information channel. 5ch is reserved for a traffic channel establishment request.

  As shown in Table 2, the base station manages 10 channel resources from 2ch to 4ch and 6ch to 12ch, monitors traffic channel establishment requests from wireless terminals with 5ch, and allocates channel resources to traffic channels Table 3 shows the types of channel signals exchanged between the wireless terminal and the wireless terminal.

  The wireless terminal has a wireless terminal ID uniquely assigned by the system, and stores the wireless terminal ID in the information symbols of all uplink channels. The base station manages the wireless terminal based on the wireless terminal ID. If the wireless terminal includes the wireless terminal ID in the downlink channel (signal) from the wireless base station, whether or not the wireless terminal is the wireless ID addressed to the wireless terminal. Judging. FIG. 5 shows a signal format used in the downlink and uplink. FIG. 5A shows a signal format used in the downlink, and FIG. 5B shows a signal format used in the uplink.

  As shown in FIG. 5A, the broadcast information channel (signal) has a known training sequence pattern, a known information symbol that is unique for each base station ID, and transmits the broadcast information channel every other frame. Do. The wireless terminal monitors the carrier 0, which is the frequency to which the broadcast information channel (signal) is allocated, and captures the received signal from the point of steep increase in energy, and knows a plurality of possible base station IDs. The correlation with the information symbol is checked, it is determined that it is the broadcast information channel of the base station having the highest base station ID, and the base station ID and timing are stored. After receiving the broadcast information channel, the reception slot position is adjusted, and synchronization with the base station is attempted. The base station and the wireless terminal determine that the frame transmitting the broadcast information channel is an even frame and the frame not transmitting the broadcast information channel is an odd frame. The start of the traffic channel is started when the wireless terminal transmits a traffic channel start request channel signal.

  In the uplink direction, both the traffic channel start request signal and the traffic channel signal have the signal format shown in FIG. The training sequence pattern is unique for each base station ID. There are three types for each base station, which are T0, T1, and T2, respectively. As the traffic channel start channel signal, T0 is fixedly used, and either T1 or T2 is used for the traffic channel. T1 relates to the spatial multiplexing number SP1 managed by the base station, and T2 relates to the spatial multiplexing number SP2. The wireless terminal performs transmission using 5ch including the ID of the wireless terminal in the information symbol of the traffic channel start channel signal. When there is a free channel resource, the base station reserves a free channel resource for the wireless terminal having the ID, and transmits a traffic channel permission signal including the channel number of the wireless resource in the information symbol. When the base station transmits a traffic channel permission signal and the wireless terminal receives the signal, in the next frame, the traffic channel is established using the radio resource of the channel number included in the traffic channel permission signal.

  The wireless terminal checks the uplink data flow rate when the traffic channel is open, and transmits a traffic channel addition request when the flow rate exceeds the traffic channel capacity. When the base station opens the traffic channel, the base station investigates the diversion of the downlink user data, and when the flow rate is larger than the currently open traffic channel, or when the traffic channel addition request is received from the wireless terminal, It is investigated whether a traffic channel of a traffic channel number to which a time slot that is not currently used with the wireless terminal belongs is free. If the traffic channel is free, the base station reserves the free channel for the wireless terminal, and the base station assigns the traffic channel number to the wireless terminal and transmits the traffic channel addition permission channel.

  FIG. 6 is a block diagram showing an outline of the internal configuration of the base station. As shown in the figure, the timing processor 210 generates frame timing shown in the TDMA-TDD frame configuration example, generation of transmission timing shown in the downlink signal format, and generation of uplink reception timing. The base station is responsible for each of the four carriers IF (intermediate frequency) signal synthesis / separation units 220, 221, 222, 223, carrier 0 channel control unit 230, carrier 1 channel control unit 231, carrier 2 channel It has a control unit 232 and a carrier 3 channel control unit 233. One IF signal synthesis / separation unit and one channel control unit control six channels that are products of three time slots on the same carrier number and two spatial multiplexing numbers.

  Hereinafter, the carrier 0 block will be described as an example, but other carrier blocks also have the same function. For example, the signal from the carrier 0 IF signal synthesis / separation unit 220 is superimposed for each antenna by the mixers MX1, MX2, MX3, MX4, MX5, MX6, and the six antennas ANT1, 1 constituting the adaptive array antenna AAA. Fired from ANT2, ANT3, ANT4, ANT5, and ANT6. At the time of uplink reception, the signal from each antenna is divided for each carrier frequency by the mixer and then distributed to the carrier 0 IF signal synthesis / separation unit 220. The signal from the carrier 0 IF signal synthesis / separation unit 220 is passed to the carrier 0 channel control unit 230 and separated into a spatial multiplexing number, and then subjected to baseband processing. In this way, the received signal that is separated and demodulated for each slot timing, carrier number, and spatial multiplexing number is passed to the main control unit 240.

  The main control unit 240 manages a plurality of user sessions, manages channel numbers and numbers used by the user sessions, and distributes user session data to each channel. The main control unit 240 passes transmission data to the channel control unit prepared for each carrier number in synchronization with the downlink transmission slot timing generated by the timing processor for each channel. For example, the carrier 0 channel control unit 230 modulates the transmission data from the main control unit 240 at the time of downlink transmission by modulating data for the number of spatial multiplexing for each slot timing by the timing processor. The signal is passed to the IF signal synthesis / separation unit 220. The carrier 0 IF signal synthesis / separation unit 220 synthesizes channel data for the number of spatial multiplexing, using the antenna weight at the time of reception of the corresponding uplink channel, and creates a transmission signal for each antenna. The mixer MX1-6 synthesizes the transmission signals from the IF signal synthesis / separation units for each carrier and emits them from the antenna ANT1-6.

  The configuration of the base station 200 will be described in further detail. FIG. 7 is a block diagram illustrating an internal configuration of the carrier 0 IF signal synthesis / separation unit 220. The block of carrier 0 will be described as an example, but the configuration and function of other carrier blocks are the same. As shown in the figure, the carrier 0 IF signal synthesis / separation unit 220 includes an RF array 220RF, SP1_TX-FPGA 220SP1, and SP2_TX-FPGA 220SP2. The RF array 220RF includes an RF unit RF1-6 for each antenna, an analog / digital converter ADC1-6, and a digital / analog converter DAC1-6.

  The timing processor 210 instructs the timing for each slot of transmission and reception. At each reception slot timing, the reception signal for each antenna from the mixer MX1-6 is demodulated by the RF unit RF1-6 prepared for each antenna constituting the RF array 220RF, and then AD-converted to IF (intermediate frequency). ) Is converted to a signal. In this way, the received signal for each antenna is separated for each carrier number, and in this case, transmitted to the carrier 0 channel control unit 230. At each transmission slot timing, downlink transmission signals and antenna weights from the carrier 0 channel control unit 230 are received for the number of spatial multiplexing. The number of spatial multiplexing is 2, and the IF signal synthesizer / separator 220 for carrier 0 has two spatial multiplexing arithmetic units (SP1_TX-FPGA) 220SP1 and SP2 spatial multiplexing arithmetic. Part (SP2_TX-FPGA) 220SP2. The SP1 spatial multiplexing operation unit 220SP1 includes a TX signal generator SG and a wait register WR. The TX signal generator SG and the wait register WR receive the SP1 transmission signal and the calculated / determined weight from the carrier 0 channel controller (DSP) 230 via the DSP-TXFPGA interface bus B2. The SP1 spatial multiplexing operation unit 220SP1 includes an antenna weight control unit (SP1_Ant1-6) W1-6 for each antenna for SP1, and each of the antenna weight control units W1-6 is a weight stored in the weight register WR. Based on the above, the antenna weight for each antenna is calculated. Then, the transmission data generated based on the signal for transmission by the TX signal generator SG is multiplied by the antenna weight for each antenna calculated by the antenna weight control unit W1-6 using a multiplier, and Create transmission data. The transmission data for each antenna created by the two TX-FPGAs are added by an adder and combined with the transmission data for each antenna. The transmission data for each antenna created in this way is AD converted, then modulated by the RF unit RF1-6, and passed to the mixer MX1-6.

  Next, the configuration of the channel control unit will be described in detail. FIG. 8 is a block diagram showing the internal configuration of the carrier 0 channel control unit 230. The block of carrier 0 will be described as an example, but the configuration and function of other carrier blocks are the same. As shown in the figure, the carrier 0 channel controller 230 is connected to the carrier 0 IF signal synthesizer / separator 220 via the DSP-TXFPGA interface bus B2 and the RXANTENNA-DSP interface bus B1. The carrier 0 channel control unit 230 is connected to the main control unit 240 via the channel control unit-main control unit interface bus B3. During uplink reception, the received IF (intermediate frequency) signal that the carrier 0 channel control unit 230 receives from the channel 0 IF signal synthesis / separation unit 220 via the RXANTENNA-DSP interface bus B1 is the traffic channel reception time. The desired wave and the interference wave included in each antenna element are superimposed. The channel control unit 230 for channel 0 applies the received IF (intermediate frequency) signal to the matched filter MF1-6 and passes the signal to the Rzz diagonal term calculation processing unit RZ. The Rzz diagonal term calculation processing unit RZ prepares for calculating the correlation with the known training by calculating the covariance matrix for each of the six received signals. The SP1 and SP2 training sequence generation units TS1 and TS2 generate the same signals as the signals given by the wireless terminal as an uplink training sequence. This is prepared for each wireless terminal for the number of spatial multiplexing. The SP1 and SP2 weight calculation units WC1 and WC2 derive the optimum antenna weight (that is, the estimated signal arrival direction) by examining the correlation between the Rzz diagonal term and the known training sequence signal. The received antenna weight and the six received IF signals are separated as received IF signals for each traffic channel of each wireless terminal. The reception IF signal for each traffic channel of each wireless terminal is processed by the SP1 and SP2 reception baseband processing units RxB1 and RxB2, and is sent as user data to the main control unit 240 via the channel control unit-main control unit interface bus B3. Forward.

  At the time of transmission of the traffic channel in the downlink, the optimal antenna weight derived at the time of reception of the corresponding uplink channel is notified to the carrier 0 IF signal combining / separating unit 220 and each radio terminal from the main control unit 240 is notified. User data for each traffic channel is converted into IF signals by the SP1 and SP2 transmission baseband processing units RxB1 and TxB2, and transferred to the carrier 0 IF signal combining / separating unit 220. In the example of this figure, the reception multiplex number and the transmission multiplex number are both 2, which matches the transmission multiplex number supported by the IF signal synthesis / separation unit.

  The SP1 and SP2 transmission stop information storage units TSM1 and TSM2 store the transmission stop information in the downlink direction instructed and transmitted from the main control unit 240. The SP1 and SP2 weight determination units WD1 and WD2 set the antenna weight in the channel to zero according to the transmission stop information read from the SP1 and SP2 transmission stop information storage units TSM1 and TSM2. As a result, the IF signal transmitted from the carrier 0 channel control unit 230 to the carrier 0 IF signal synthesis / separation unit 220 has zero weight at all antennas, and thus emission of radio waves is suppressed. That is, it becomes possible to control the channel usage state (transmission state). The merit of using the antenna array in the TDMA-TDD system is that the antenna weight estimated by the uplink reception is used as the downlink antenna weight as it is, and the appropriate downlink radio wave is emitted to the same radio wave propagation path. It can be done. That is, uplink reception is necessary for downlink transmission in the base station, but there is no problem in not performing downlink.

  Next, the configuration of the main control unit 240 will be described in detail. FIG. 9 is a block diagram showing an internal configuration of the main control unit 240. As shown in the figure, the main control unit 240 includes a flow management unit 241, a channel allocation management unit 242, a downlink flow rate monitoring unit 243, and a transmission stop / start management unit 244. The flow management unit 241 associates a user session with a traffic channel. The channel allocation management unit 242 stores the usage status of 20 ((3 slots × 4 carriers) −2) × 2 spatial multiplexing) spatially multiplexed traffic channels in a storage unit (not shown), and creates a new Performs control to allocate an available traffic channel when adding traffic. Transmission data from an upper layer UL1, UL2,... UL8 of an arbitrary user session is distributed to the traffic channel used by the user session. For each time slot timing of the traffic channel, the flow management unit 241 stores data corresponding to the carrier and the spatial multiplexing number among the downlink flow rate monitoring units DF1-8 separated by the carrier and the spatial multiplexing number. Send. The downlink flow rate monitoring unit 243 (DF1-8) investigates the traffic channel flow rate for each user session and notifies the transmission stop / start management unit 244 and the flow management unit 241. When the flow management unit 241 compares the capacity corresponding to the number of aggregates of the traffic channel with the total flow rate of the downlink of the user session for each user session, and determines that fewer traffic channels are required, A downlink slot stop instruction channel is transmitted. When the wireless terminal receives the downlink slot stop instruction channel, the wireless terminal transmits a downlink slot stop response instruction channel and performs control not to turn on the LNA switch when the traffic channel is received next time.

  Next, the configuration of a wireless terminal that is a communication partner of the base station described above will be described. FIG. 10 is a block diagram illustrating a configuration of the wireless terminal 300. As shown in the figure, the wireless terminal 300 has only one antenna ANT10. The wireless terminal 300 includes a timing processor (scheduler) 310, a circulator 320, and an upper layer UL. The wireless terminal 300 includes a plurality of mixers, a digital analog converter DAC, an analog digital converter ADC, a power amplifier PA, a low noise amplifier LNA, a temperature compensated voltage control crystal oscillator VCTCXO, an RF phase lock loop RF-PLL, and an IF phase lock loop IF. A PLL, a channel allocation management unit 340, a flow management unit 350, an uplink flow rate monitoring unit 360, and a reception stop / start management unit 370 are further included. Since the downlink reception signal in the radio terminal 300 is received as a transmission radio wave using an antenna weight adjusted to be suitable for the propagation path by the base station, the interference wave from the same base station is suppressed. Therefore, the wireless terminal 300 does not need to be aware of spatial multiplexing for each traffic channel. Therefore, as shown in FIG. 10, it is simpler than the internal configuration of the base station.

  The timing processor 310 generates transmission and reception timing according to the TDMA-TDD frame. At the downlink reception timing in an arbitrary time slot number, the reception signal received from the antenna ANT10 is amplified by the low noise amplifier LNA. Prior to reception, the baseband processing unit 330 changes the frequency setting according to the carrier number of the traffic channel received for the VCTCXO. The received signal amplified by the LNA is converted into an IF (intermediate frequency) signal by a two-stage mixer, sampled by an analog-digital converter ADC, and converted into digital data. The received IF signal is demodulated by the baseband processing unit 330. The flow management unit 350 combines received data from a plurality of traffic channels and converts the received data into received user data.

  At the uplink transmission timing at an arbitrary time slot number, the user data is transferred from the flow management unit 350 to the baseband processing unit 330 as the traffic channel of the time slot. This user data is divided when a plurality of traffic channels are used. Prior to transmission, the baseband processing unit 330 changes the frequency setting to correspond to the carrier number of the traffic channel transmitted to the VCTCXO. The baseband processing unit 330 modulates transmission user data and converts it into a transmission IF signal. The transmission IF signal is modulated to a transmission frequency corresponding to the carrier number by a two-stage mixer, amplified by a power amplifier PA, and then emitted from the antenna end of the antenna ANT10.

  Here, it is assumed that, for example, a maximum of three traffic channels can be provided for one user session. A separate traffic channel is used for each time slot. It is assumed that two traffic channels are established between the base station and the wireless terminal. The uplink data traffic volume is large and two traffic channels are required, but if the base station determines that one traffic channel is sufficient for the downlink data stream, the downlink traffic channel is Since there is no data to be transported, dummy data will be transmitted. The traffic channel is shared between other spatial terminals connected to the same base station and users connected to other base stations. Since meaningless radio wave emission becomes an interference wave in communication with other wireless terminals sharing the traffic channel, it is preferable not to emit the radio wave.

  In order to solve the above-described problem, processing based on the flowchart shown in FIG. 11 is performed, and control for stopping transmission in the downlink direction is performed. FIG. 11 is a flowchart illustrating a process of stopping transmission in the downlink direction according to the present invention. As shown in the figure, in step ST1, the determination result of the downlink flow rate monitoring unit is acquired. If the result of determination in step ST2 is that the slot can be thinned (stopped), the process proceeds to step ST3, and a downlink slot stop instruction signal is transmitted to the wireless terminal. Thereafter, in step ST4, it is determined whether or not a “stop response” that is a response to the downlink slot stop instruction signal is received. If the stop response is not received, the process ends. If it is received, the process proceeds to step ST5, and the data to be sent to the stopped slot (channel) is sent to the remaining “in-use / in-use slots (channel)” that are not stopped. In addition, the retransmission control data for the uplink slot corresponding to the stopped downlink slot is integrated into the retransmission control data of the “active slot (channel)”. Finally, the process proceeds to step ST6, the transmission management unit is notified of the stop of the downlink slot, and the process ends.

  When the condition in step ST2 is not satisfied, the process proceeds to step ST7, and it is determined whether the stopped slot is necessary as an additional slot based on the determination result acquired in step ST1. If the stopped slot is not necessary as an additional slot, the process ends. If necessary, the process proceeds to step ST8, and a downlink slot restart instruction signal is transmitted to the wireless terminal. Next, in step ST9, it is determined whether or not a “resume response signal” that is a response to the downlink slot restart instruction signal is received from the wireless terminal. If the "restart response signal" is not received, the process ends. If it is received, the process proceeds to step ST10, and the data integrated as data to be sent to the remaining "in-operation slot (channel)" is restarted. The retransmission control data for the stopped slot that has been integrated into the “active slot (channel)” is further separated. Finally, proceeding to step ST11, the transmission management unit is notified of the resumption of the downlink slot, and the process ends.

  Through the above processing, the radio terminal can stop radio wave emission in the downlink direction when there is much uplink traffic but there is little downlink traffic. As a result, unnecessary radio wave emission can be reduced, and interference in the downlink direction between the wireless terminal and the base station using the same traffic channel can be reduced. As a result, the frequency of the entire system can be reduced. It becomes possible to improve utilization efficiency. Moreover, the effect of battery saving can be obtained by preventing the wireless terminal from receiving unnecessary radio waves. In a wireless terminal, the consumption current of the reception amplifier often occupies a considerable portion with respect to the entire consumption current, and reducing the time during which the reception amplifier switch is on as much as possible contributes to battery saving. When reception of radio waves in the downlink direction of one traffic channel is omitted in the state where two traffic channels are used, the current consumption in the receiving amplifier and a circuit subsequent to the receiving amplifier can be halved.

  FIG. 12 is a sequence diagram illustrating a process of stopping a downlink slot by the control method according to the present invention. As shown in the figure, there are two uplink channels (slots) from the wireless terminal side to the base station side, and two uplink messages (signals) U11 and U12 are transmitted within one frame. On the other hand, there are two downlink channels (slots) from the base station side to the wireless terminal side, and two downlink messages (signals) D11 and D12 are transmitted in one frame. In the present invention, the slot on the uplink side is not stopped and controlled, so that two slots are always in operation, two uplink messages, two pairs of uplink messages (signals) U13 and U14, uplink messages (signals). It is transmitted in the form of a pair of U15 and U16 and a pair of uplink messages (signals) U17 and U18.

  On the base station side, in process P1, the downlink flow rate monitoring unit determines that one downlink slot may be stopped, and a downlink message D13 including a downlink slot stop instruction signal using the slot to be stopped. Is sent to the terminal. In another slot, a downlink message D14 storing traffic data in which data to be transmitted for the downlink of the slot to be stopped and retransmission control data for two uplink slots is stored is transmitted. The terminal side that has received the downlink message D13 including the downlink slot stop instruction signal transmits an uplink message U15 including a downlink slot stop response signal and a normal uplink message U16 using the same slot. Upon receiving the uplink message U15 including the downlink slot stop response signal, the base station stops the corresponding slot (channel), and thereafter transmits one downlink message D15 using one active slot. To do. One downlink message D16 is also transmitted at the subsequent frame timing.

  FIG. 13 is a sequence diagram illustrating a process of resuming a downlink slot that has been stopped by the control method according to the present invention. As in FIG. 12, there are two uplink channels (slots) from the wireless terminal side to the base station side, and two uplink messages (signals) U21 and U22 are transmitted in one frame. After that, two pairs of uplink messages (signals) U23 and U24 and a pair of U25 and U26 are transmitted one by one in one frame. On the other hand, there are two downlink channels (slots) from the base station side to the wireless terminal side, but one slot (channel) is stopped by the control of the present invention, so one downlink message (signal) D21. Are transmitted within one frame. After transmitting the downlink message (signal) D21, in Step P2, it is determined that the downlink slot that has been stopped by the downlink flow rate monitoring unit on the base station side needs to be restarted. Thereafter, using one active slot, a downlink message D22 including a downlink slot restart instruction signal is transmitted to the terminal side. Receiving this, the terminal side transmits an uplink message U25 including a downlink slot restart response signal. Upon receiving the uplink message U25 including this downlink slot restart response signal, the base station side restarts the stopped slot (channel) and transmits the downlink messages D23 and D24 using the two slots. Also in subsequent frames, two downlink messages D23 and D24 are transmitted per frame. In this way, depending on the downlink flow rate, it is possible to reduce or reduce the power consumption on the receiving side and to reduce the radio interference on the receiving side by stopping and restarting the slot (channel) as needed. Become.

  The advantages of the present invention will be described again. When there is a large amount of data traffic from the wireless terminal to the base station and channel aggregation is performed to cope with this, conversely, there is little data traffic from the base station to the wireless terminal, and only the direction from the base station to the wireless terminal is considered. Thus, channel aggregation in the direction from the base station to the wireless terminal does not have to be performed in a state where channel aggregation is not originally required. This prevents unnecessary radio waves from being emitted from the base station to the wireless terminal, and is unnecessary for wireless terminals communicating with the base station in the same spatial multiplexing and wireless terminals on the same frequency communicating with other neighboring base stations. So that you do n’t have to be disturbed. In addition, unnecessary radio waves are not received at the wireless terminal, unnecessary battery consumption can be prevented, and standby time and communication time can be extended. Alternatively, since battery consumption can be suppressed, standby time and communication time can be achieved even if the battery is downsized. After stopping unnecessary radio wave emission, it is possible to allocate the resource to another wireless terminal, leading to improvement in frequency utilization efficiency. Alternatively, in the traffic channel formed second, it is possible to independently increase or decrease the number of aggregates from the base station to the radio terminal without being affected by the radio terminal to the base station.

  Thus, according to the present invention, in a system for establishing a digital communication path between a base station and a wireless terminal using the TDMA-TDD scheme, for example, there is a lot of data traffic from the wireless terminal to the base station, and By determining when the data traffic from the base station to the wireless terminal is low and increasing or decreasing the number of channel aggregates from the base station to the wireless terminal, it is possible to prevent unnecessary radio waves from being emitted from the base station to the wireless terminal. In addition to improving the frequency utilization efficiency of the system, it is possible to extend the battery communication time by preventing unnecessary reception of radio waves on the wireless terminal side.

  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.

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 structural example of the radio | wireless communications system by one embodiment of this invention. It is a figure which shows the frame format example of TDMA-TDD. It is a figure which shows arrangement | positioning of the carrier (frequency) used by this embodiment. It is a figure which shows the signal format used by a downlink and an uplink. It is a block diagram which shows the outline of an internal structure of a base station. 3 is a block diagram showing an internal configuration of a carrier 0 IF signal synthesis / separation unit 220. FIG. 3 is a block diagram showing an internal configuration of a carrier 0 channel control unit 230. FIG. 3 is a block diagram showing an internal configuration of a main control unit 240. FIG. 2 is a block diagram showing a configuration of a wireless terminal 300. FIG. It is a flowchart which shows the process which stops transmission of the downlink direction by this invention. It is a sequence diagram explaining the process which stops a downlink slot with the control method by this invention. It is a sequence diagram explaining the process which restarts the downlink slot which was stopped with the control method by this invention.

Explanation of symbols

100 wireless communication apparatus 110 control unit 120 channel allocation management unit 130 downlink flow rate monitoring unit 140 reception unit 150 transmission unit 160 downlink channel transmission state control unit 170 storage unit TB1 channel allocation table TB2 reference flow rate table AA, AAA adaptive array Antenna ADC, ADC1 Analog to digital converter ANT1, ANT2, ANT3, ANT4, ANT5, ANT6, ANT10 Antenna B1 RXANTENNA-DSP interface bus B2 DSP-TXFPGA interface bus B3 Channel control unit-main control unit interface bus BS1, BS2 Base station DAC, DAC1 Digital / analog converter DF1-8 Downlink flow rate monitor IF-PLL IF phase lock loop LNA Low noise amplifier MX1, MX2, MX3, MX , MX5, MX6 Mixer PA Power amplifier RF-PLL RF phase lock loop RF1-6 RF unit RxB1, RxB2 SP1, SP2 reception baseband processing unit RxB1, TxB2 SP1, SP2 transmission baseband processing unit RZ Rzz diagonal term for each antenna Calculation processor SG Signal generator TM1, TM2 Wireless terminal TS1, TS2 Training sequence generator TSM1, TSM2 Transmission stop information storage UL, UL1, UL2, UL8 Upper layer VCTCXO Temperature compensated voltage control crystal oscillator W1-6 Antenna weight controller WC1, WC2 SP1, SP2 weight calculation unit WD1, WD2 SP1, SP2 weight determination unit WR wait register 200 base station 210 timing processor 220 carrier 0 IF signal synthesis / separation unit 221 carrier 1 IF signal combination Generator / separator 222 IF signal synthesis / separation unit 223 for carrier 2 IF signal synthesis / separation unit 220RF for carrier 3 spatial multiplexing operation unit 230 for RF array 220SP1, SP2 SP1, SP2, channel control unit 231 for carrier 0 channel for carrier 1 Control unit 232 Channel control unit for carrier 2 Channel control unit for carrier 2 240 Main control unit 241 Flow management unit 242 Channel allocation management unit 243 Downlink flow rate monitoring unit 244 Transmission stop / start management unit 300 Wireless terminal 310 Timing processor 320 Circulator 330 Baseband processing unit 340 Channel allocation management unit 350 Flow management unit 360 Uplink flow rate monitoring unit 370 Reception stop / start management unit

Claims (7)

A channel composed of an uplink-side channel and a downlink-side channel set in the plurality of time slots using a time division multiple access / time division duplex method having a plurality of time slots in communication with a wireless terminal A method of controlling a wireless communication device that assigns a plurality of pairs to the wireless terminal,
An acquisition step of acquiring a data traffic amount of a downlink side channel included in the plurality of allocated channel pairs;
A control step of controlling a use state of at least one downlink side channel included in a plurality of channel pairs allocated to the wireless terminal according to the acquired data traffic amount of the downlink side channel;
A control method for a wireless communication apparatus, comprising: The method of controlling a wireless communication apparatus according to claim 1,
Defined according to the data traffic volume of the downlink side channel acquired in the acquisition step and the downlink side channel in use among the downlink side channels included in the plurality of channel pairs allocated to the wireless terminal A comparison step for comparing with a threshold to be performed;
The control step comprises:
When the amount of data traffic on the downlink side channel is smaller than the threshold value by the comparison step, the usage state of at least one downlink side channel included in a plurality of channel pairs assigned to the wireless terminal is controlled.
A method for controlling a wireless communication apparatus. In the control method of the radio | wireless communication apparatus of Claim 1 or 2,
The control step comprises:
Controlling the use state of the at least one channel by stopping at least a part of transmission using at least one downlink side channel included in the plurality of channel pairs allocated to the wireless terminal;
A method for controlling a wireless communication apparatus. In the control method of the radio | wireless communication apparatus of any one of Claims 1-3,
A notification step of notifying the wireless terminal that the usage state of the at least one downlink side channel is controlled before executing the control step;
A reception step of receiving a response permitting the control from the wireless terminal notified by the notification step;
The control step comprises:
Controlling usage of the at least one downlink side channel after receiving the response;
A method for controlling a wireless communication apparatus. In the control method of the radio | wireless communication apparatus of any one of Claims 1-4,
When the use state of the at least one channel is controlled by the control step, the use state of the at least one channel on the downlink side is returned to a normal state according to the amount of data traffic on the downlink. Step to control,
A method for controlling a wireless communication apparatus, further comprising: In the control method of the radio | wireless communication apparatus of any one of Claims 1-5,
Each of the plurality of time slots is spatially multiplexed.
A method for controlling a wireless communication apparatus. A channel composed of an uplink-side channel and a downlink-side channel set in the plurality of time slots using a time division multiple access / time division duplex method having a plurality of time slots in communication with a wireless terminal A wireless communication device for assigning a plurality of pairs to the wireless terminal,
A downlink flow rate monitoring unit for acquiring a data traffic volume of a downlink side channel included in the plurality of allocated channel pairs;
A downlink channel transmission state control unit that controls a transmission state of at least one downlink side channel included in a plurality of channel pairs allocated to the wireless terminal according to the acquired data traffic amount of the downlink side channel When,
A wireless communication apparatus comprising:

Images