JP2009010529A - Communication device, system, and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for realizing automatic retransmission control (ARQ) when unidirectional communication channel aggregation technology is used. <P>SOLUTION: A communication device (100) for communication between the other side communication device and an own device includes a communication part (110) that communicates between the other side communication device and the own device by performing communication via a bidirectional communication channel and communication via at least a unidirectional communication channel, a feedback information acquiring part (130) for acquiring the feedback information for the signal transmitted from the other side communication device to the own device via at least the unidirectional communication channel established by the communication part and received by the communication part, and a control part (120) which controls the communication part to transmit the feedback information for at least the unidirectional communication channel acquired by the feedback information acquiring part to the other side communication device via the bidirectional communication channel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication apparatus, a communication system, and a communication method, and more particularly, to an automatic retransmission in a data communication path on the premise of missing data in a communication system that supports an asymmetric number of channels (unidirectional channel allocation) in a communication direction. The present invention relates to a communication device, a communication system, and a communication method for realizing control (ARQ; Automatic Repeat reQuest).

  Data / packet communication paths that are based on the lack of data such as packets are used in both wired and wireless communication systems. In the wireless communication system, the error rate is significantly higher than that of the wireless communication system even at a short distance, and therefore it is essential to apply automatic retransmission control. In the wireless communication scheme, the error rate increases according to the distance between the base station and the user terminal. Further, regardless of the wired communication method or the wireless communication method, when data traffic increases and data collision occurs, data is lost. On the other hand, in the wired communication system, the quality of the communication path is generally good. For example, in ADSL (Asynchronous Digital Subscriber Line), the distance between the accommodation station (base station) and the subscriber's home (user terminal) is The longer it is, the higher the error rate, and data loss will occur accordingly. That is, it is necessary to apply automatic retransmission control even in a wired communication system.

  There are various wireless communication methods, for example, there are PHS (Personal Handyphone System) and iBurst (registered trademark) systems in communication systems compliant with wireless communication standards using the TDMA-TDD communication method, Specified in “ARIB STD-28 (ARIB)” (Non-patent Document 1) and “High Capacity-Spatial Division Multiple Access (HC-SDMA) WTSC- 2005-032 (ATIS / ANSI)” (Non-patent Document 2), respectively. ing.

  In the wireless communication system, one or both of the two communication devices that perform communication may be movable. When the distance between the communication devices exceeds the wireless propagation distance due to movement, communication is performed during that period. It will be lost. Even if the communication apparatus does not move, there is a period in which communication is interrupted due to a change in the radio wave propagation path. Thus, in the wireless communication system, it is very difficult to avoid interruption in the middle of communication. As described above, in order to perform packet-based communication on a route that is interrupted during communication, the reliability of the communication route can be improved by implementing ARQ.

<About ARQ>
ARQ (Automatic Repeat reQuest) is a communication route that generally assumes that there is a packet loss. By sending feedback of information from the receiving side, the sender knows the sequence number of the lost packet and retransmits the packet with the missing sequence number. Is a mechanism for automatically performing the above, and is a known technique. Examples of ARQ in wireless communication devices include “High Capacity-Spatial Division Multiple Access (HC-SDMA) WTSC-2005-032 (ATIS / ANSI)”. A configuration example of ARQ is shown as part of L2 RLC (Layer 2 Radio Link Control) in this document. As a basic mechanism, the transmission side stores the sequence number of the last byte of data to be carried in the packet header and transmits it. The receiving side returns the sequence number of the last byte of the most recent data sequence among the data sequences that have been successfully received out of the successfully received data sequence as Ack (acknowledgment) to the transmitting side. When only the sequence number older than the sequence number of the data that should have been transmitted is obtained, the transmission side retransmits the data string following the sequence number obtained as Ack. The receiving side sets the sequence number included in Ack to the sequence number of the latest byte of the received data by filling the gap by receiving the retransmission packet.

GBN type (Go Back N-Type) and SR type (Selective Repeat-Type) have been devised for ARQ. The GBN type is a method of retransmitting in order, going back to the sequence number of the missing data indicated by the reception confirmation information Ack included in the feedback information from the receiving side. On the other hand, the SR type retransmits “only the data of the sequence number that would have been lost” based on the successfully received sequence number indicated by Ack included in the feedback information from the receiving side, and thereafter Is a method for transmitting new data. In general, it is known that SR-type ARQ can obtain a better throughput in a communication path having a high frequency of missing such as a wireless communication path or satellite communication and a large round trip time RTT. However, since SR-type ARQ continues to send new data ahead of time, in the case of a transmission path with many missing data, the transmission data that has not received Ack is the number of outstanding (the maximum number of packets that can be transmitted without receiving Ack) It is easy to reach. In "High Capacity-Spatial Division Multiple Access (HC-SDMA) WTSC- 2005-032 (ATIS / ANSI)", SR type ARQ is used until the number of outstanding is reached, and when it reaches the number of outstanding, it is received by Ack. A control technique is disclosed that goes back to the sequence number of data that has not been confirmed and retransmits the data in order from the sequence number.
Standard “ARIB STD-28 (ARIB)”, Radio Industry Association “High Capacity-Spatial Division Multiple Access (HC-SDMA) WTSC- 2005-032 (ATIS / ANSI)”

  The above-described automatic retransmission technique on a transmission path premised on data loss is intended for a communication system using a bidirectional communication channel having an uplink channel and a downlink channel in wireless communication and wired communication. Various technologies have been developed in communication systems that use two-way communication channels. In such an automatic retransmission technology, for example, when data loss occurs in a downlink channel, whether it is GBN type or SR type, via an “uplink channel” paired with the downlink channel. The communication device has been configured to send some feedback information (typically an Ack that contains the sequence number of the packet that was successfully received).

  On the other hand, in the communication system that performs channel aggregation in which an additional bidirectional communication channel is allocated according to the data flow rate while basically using the bidirectional communication channel, the applicant of the present invention is classified into uplink and downlink. Depending on the data flow situation, “one side (unidirectional) channel only” constituting the bidirectional communication channel is stopped (or restarted), or “unidirectional communication channel only” is newly added ( Or a new one-way communication channel aggregation technique that is different from the conventional one (this communication technique will be described later). In such a communication system in which the number of channels is asymmetric (unidirectional channel allocation) between the uplink and the downlink, there exists a “unidirectional communication channel” that does not have a communication channel in the opposite direction. When data loss occurs in such a “unidirectional communication channel”, a “unidirectional communication channel to form a channel pair with the unidirectional communication channel used when sending feedback information (retransmission request)” "Does not exist, and feedback information (retransmission request) cannot be transmitted. Therefore, the conventional automatic retransmission technique based on the bidirectional communication channel composed of the uplink channel and the downlink channel can be applied to a communication system using the “unidirectional communication channel aggregation technique” developed by the present applicant. It was impossible.

  Accordingly, an object of the present invention is to provide a technique (communication apparatus, communication system, and communication method) that realizes automatic repeat control (ARQ) when using the unidirectional communication channel aggregation technique as described above. It is to be.

In order to solve the above-described problems, a communication device according to the present invention provides:
A communication device that performs communication between a partner communication device and its own device,
A communication unit that establishes communication in a bidirectional communication channel and communication in at least one unidirectional communication channel between the counterpart communication device and the own device; and
A feedback information acquisition unit for acquiring feedback information for a signal transmitted from the counterpart communication device to the own device via the at least one unidirectional communication channel established by the communication unit and received by the communication unit;
A control unit that controls the communication unit to transmit feedback information for the at least one unidirectional communication channel acquired by the feedback information acquisition unit to the counterpart communication device via the bidirectional communication channel; ,
With

The communication device according to the second invention is
The type field identifier (for example, bit pattern) of the signal exchanged between the counterpart communication apparatus and the own apparatus is associated with the position in the exchanged signal of the feedback information for the unidirectional communication channel. Further comprising a storage unit for storing the table,
It is characterized by that.

The communication device according to the third invention is
The control unit is
The communication unit is configured to transmit a signal in which feedback information for the at least one unidirectional communication channel is arranged at a position corresponding to the correspondence of the table to the counterpart communication device via the bidirectional communication channel. Control,
It is characterized by that.

A communication device according to a fourth invention is
A plurality of the unidirectional communication channels;
The control unit is
The feedback information in each of the plurality of unidirectional communication channels is transmitted to the counterpart communication device via the bidirectional communication channel, with the signals arranged at positions corresponding to the correspondence of the table. Control the communication part,
It is characterized by that.

A communication system according to a fifth invention is
A communication system for performing communication between a first communication device and a second communication device,
The first communication device is
A communication unit that establishes communication in a bidirectional communication channel and communication in at least one unidirectional communication channel between the second communication device and the own device; and
A feedback information acquisition unit for acquiring feedback information for a signal transmitted from the second communication device to the own device and received by the communication unit via the at least one unidirectional communication channel established by the communication unit; ,
A control unit that controls the communication unit to transmit feedback information for the at least one unidirectional communication channel acquired by the feedback information acquisition unit to the second communication device via the bidirectional communication channel. And
The second communication device is
A communication unit that establishes communication in a bidirectional communication channel and communication in at least one unidirectional communication channel between the first communication device and the own device; and
Receiving a signal transmitted from the first communication device via the bidirectional communication channel and including feedback information for the at least one unidirectional communication channel, and depending on the information included in the received signal, the at least A control unit that controls the communication unit to adaptively adjust a modulation scheme of one unidirectional communication channel;
It is characterized by that.

A communication system according to a sixth invention is
The first communication device is
Corresponds between an identifier (for example, a bit pattern) of a type field of a signal exchanged between the second communication device and the own device and a position of feedback information for the unidirectional communication channel in the exchanged signal. A storage unit for storing the attached table;
It is characterized by that.

A communication system according to a seventh invention is
The control unit in the first communication device is
The communication unit is configured to transmit a signal in which feedback information for the at least one unidirectional communication channel is arranged at a position corresponding to the correspondence of the table to the second communication device via the bidirectional communication channel. To control the
It is characterized by that.

A communication system according to an eighth invention is
The second communication device is
An identifier (for example, a bit pattern) of a type field of a signal exchanged between the first communication device and the second communication device, and feedback information for a unidirectional communication channel in the exchanged signal. A storage unit for storing a table in which the position is associated;
The control unit in the second communication device is
Referring to the table, feedback information for the at least one unidirectional communication channel is acquired from the received signal, and a modulation scheme of the at least one unidirectional communication channel is adaptively determined according to the acquired information To adjust,
It is characterized by that.

As described above, the solving means of the present invention has been described as an apparatus (system). However, the present invention can also be realized as a method, a program, and a storage medium recording the program. It should be understood that these are included in the scope of the invention.
For example, the communication method according to the ninth aspect of the present invention that realizes the present invention
A communication method for performing communication using an adaptive modulation method between a first communication device and a second communication device,
Communication in which the first communication device establishes communication on the bidirectional communication channel and communication on at least one unidirectional communication channel between the second communication device and the own device. Steps,
Feedback information of a signal transmitted from the second communication apparatus to the own apparatus through the at least one unidirectional communication channel established by the communication step and received by the communication unit. A feedback information acquisition step to acquire,
The first communication device transmits feedback information for the at least one unidirectional communication channel acquired in the reception signal quality acquisition step to the second communication device via the bidirectional communication channel. Control steps to control,
The second communication device receives a signal transmitted from the first communication device via the bidirectional communication channel and including feedback information for the at least one unidirectional communication channel, and responds to the received signal. A control step for controlling to adaptively adjust a modulation scheme of the at least one unidirectional communication channel;
It is characterized by having.

  According to the present invention, in a transmission system having an asymmetric number of channels in the transmission direction, there is no paired channel, and acknowledgment of transmission data in a unidirectional channel is borrowed from the reverse channel of another channel pair. Thus, ARQ can be made to function. By realizing ARQ in a transmission method having an asymmetric channel number in the transmission direction, it is possible to provide both a highly reliable transmission path and a transmission path with high frequency effective utilization efficiency. Furthermore, since it is not necessary to transmit an Ack via the unidirectional channel, the throughput of the unidirectional channel can be improved as a result.

  Prior to the description of the principle and configuration of the present invention, a communication system, a time slot configuration targeted by the present invention, a “unidirectional communication channel aggregation technique” developed by the present applicant, and the like will be described.

<Adaptive antenna array>
As an example of a communication system targeted by the present invention, an adaptive antenna array system will be described. 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 due to reception. In addition, the adaptive antenna array ensures the communication quality by setting the transmit antenna weight so that the signal to interference and noise ratio (SINR) is maximized and the signal is suppressed otherwise for the wireless terminal to be estimated. However, since the link capacity can be drastically increased, research has become active recently. 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>
The TDMA-TDD (Time Division Multiple Access-Time Division Duplex) method uses the same frequency for the uplink channel from the wireless terminal to the base station and the downlink channel from the base station to the wireless terminal. Since the antenna weight obtained by reception in theory can be used for transmission, there is an advantage that performance improvement using an antenna array can be easily obtained. In other words, in the same frequency band in a short period, it is assumed that there is continuity between the propagation path itself and the propagation characteristics in the propagation path between any point and any other point, and the uplink from the wireless terminal to the base station It is assumed that the antenna superposition coefficient obtained by receiving the direction and matching the propagation path can be used for downlink transmission. In general, this assumption is sufficiently practical when the interval between the reception signal and the transmission signal used for estimation is short and the moving speed of the wireless terminal is low.

<How to obtain antenna weight>
The Wiener solution is well known as an antenna weight, and the mean square error (MSE) between the training signal (known reference signal) and the received signal from the receiving antenna array is minimized as a method to obtain the Wiener solution. It is known that sequential updating by an adaptive 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 commonly 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, if 3 times are multiplexed in time by TDMA-TDD and 4 frequency channels are available, 12 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. The unused state is determined by measuring the interference of uplink radio channel resources on the wireless terminal side. If the measured RSSI (Received Signal Strength Indicator) is less than or equal to the threshold value, it is determined that the channel is unused. There is a way to fire a start request signal. It is known that the use of the ALOHA algorithm with SLOT, 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 the pattern.

<Link adaptation>
In wireless communication systems, the transmission status of each other's transmission is known by feedback from the receiving side, and based on this information, for example, the transmission output and the modulation system to be selected when multiple modulation systems are supported are adaptively changed. However, there is a link adaptation technology that maintains optimal wireless communication. For example, “High Capacity-Spatial Division Multiple Access (HC-SDMA) WTSC-2005-032 (ATIS / ANSI)” discloses a specific method. Yes.

<Unidirectional communication channel aggregation technique>
The communication system that supports SDMA is characterized in that the same frequency is spatially divided by the operation of the adaptive antenna array. However, radio waves used for communication between certain communication devices can also share the same frequency. It becomes an interference wave in the communication of this communication device. In order to reduce this interference wave and increase the effective utilization efficiency of radio waves (frequency), the present applicant has developed a unidirectional communication channel aggregation technique.

  In this “unidirectional communication channel aggregation technique”, in a communication system using SDMA, paying attention to the asymmetry of the uplink and downlink traffic flow in the server client model, for example, two or more channels are provided for each direction. In a situation where the traffic flow requires two or more channels in one direction and the traffic flow in the opposite direction is sufficient with a smaller number of channels, only one channel can be used. Reducing technology. Alternatively, the unidirectional communication channel aggregation technique relates to a technique of adding only a channel in a direction in which the bandwidth is insufficient in a situation where the bandwidth of one channel is insufficient. In other words, by eliminating unnecessary emission of radio waves, it is possible to reduce the interference wave to other communication devices using the same frequency, and to improve the effective radio wave utilization rate of the entire system. Become. As a secondary effect, when the wireless terminal is battery-powered, there is an effect of reducing the radio terminal's radio wave emission or radio wave reception opportunity when the traffic flow rate in one direction is low, which is useful for battery saving. There is a contributing effect.

  In conventional ARQ, a channel pair transmits an acknowledgment (Ack) as feedback information for data transmission via one channel of the channel pair using the other channel of the channel pair. Unidirectional communication that does not constitute a channel pair and does not have a path for transmitting feedback information, even if the conventional ARQ is applied to the "unidirectional communication channel aggregation technique" developed by the present applicant with an asymmetric channel number. A channel may exist and ARQ will not work. Even when there is no channel to be paired and there is no path for transmitting feedback information, it is possible to make ARQ, that is, automatic retransmission control function by applying the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention can be applied regardless of whether it is wireless communication or wired communication. However, in general, the present invention is applied to a wireless communication system having a high error rate and a large merit for applying the present invention. This will be described in detail. 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 apparatus 100 includes a communication unit 110 (reception unit 110R, transmission unit 110T), a control unit 120 that controls the entire apparatus, a feedback information acquisition unit 130, a storage unit 140, and a channel assignment management unit 150. A channel flow rate monitoring unit 160, a channel transmission state control unit 170, and an adaptive array antenna AA. When there is data to be transmitted to a communication partner wireless terminal having a session with the own device, the control unit 120 controls the transmission unit 110T to transmit the data via the adaptive array antenna AA. The adaptive array antenna AA has a plurality of antenna elements, and each antenna element corresponds to the antenna weight calculated for each antenna element based on the received signal for each antenna element received by the receiving unit 110R of the communication unit 110. A radio wave is emitted (this antenna weight will be described in detail later). The channel allocation management unit 150 manages channel allocation in a session between the own apparatus and a communication partner wireless terminal, and stores the channel allocation status in the channel allocation table TB2 in the storage unit 140. The storage unit 140 is further provided with a reference flow rate table TB3, which stores the maximum transmission flow rate and the reference flow rate (threshold value) corresponding to the number of channels for each direction. For example, the uplink is as shown in the table below.

  For example, the channel flow rate monitoring unit 160 acquires the data traffic volume of the allocated uplink channel. The amount of data traffic may be received from the wireless terminal as the uplink data amount staying on the wireless terminal side, or may be obtained from the data amount of the uplink signal received on the base station side. For example, when the data traffic volume of the acquired uplink-side channel exceeds the reference flow rate (threshold value) of the corresponding number of channels in Table 1 (TB3), the channel allocation management unit 150 Instead of a channel pair (slot pair or two-way communication channel) composed of an uplink-side channel and a downlink-side channel, “only an additional uplink-side channel” is newly allocated. The channel assignment management unit 150 stores and manages the situation such as channel assignment / release / stop on the additional uplink side in the channel assignment table TB2. For example, when one uplink channel is allocated and the uplink flow rate of the session exceeds the reference flow rate of 100 kbps when there is one channel, only the additional uplink channel is newly allocated. . When the uplink flow rate becomes less than the reference flow rate of 100 kbps, the transmission state of the newly allocated additional uplink channel is controlled. For example, stop at least a part of transmission (for example, stop a part of the time interval in one slot of the channel or the entire transmission, or stop a slot intermittently at intervals of one or more frames). To control the use state (that is, transmission state and antenna weight) of the additional uplink channel. Thus, by controlling the transmission state, it becomes possible to reduce power consumption without releasing resources (additional uplink side channels). If the uplink flow rate increases again and exceeds the reference flow rate, the resource (additional uplink side channel) can be immediately reused because the resource allocation has been completed. .

  Also, as described above, when a total of two uplink channels are allocated by newly allocating additional uplink channels, the uplink flow rate of the session exceeds the reference flow rate of 200 kbps when there are two channels. In this case, it is also possible to newly allocate one additional uplink channel (a total of three) and transmit uplink data using a total of three channels. In this way, depending on the uplink flow rate, by assigning only the uplink channel on an ad hoc basis, or by stopping or restarting the transmission state, unnecessary downlink side (base station side) radio waves Can be suppressed. In addition, the power consumption of the wireless terminal that transmits the uplink signal is reduced by stopping the transmission of the uplink side channel, and further, another channel that is a slot having the same timing as the channel and that uses the same carrier and is spatially multiplexed. Interference with (slot) can also be reduced. Furthermore, the wireless terminal can keep up with the additionally allocated channel and cope with the fluctuation of the uplink flow rate in the subsequent communication. That is, according to this method, since the channel is not released, the uplink data can be used without changing the reference flow rate / threshold value (or the maximum transmission flow rate) as defined according to the number of transmission state channels at that time. Only when this is the case, there is an advantage that transmission of the channel on the uplink side can be resumed immediately without requiring channel reassignment. 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.

  Further, when the uplink flow rate becomes less than the reference flow rate of 100 kbps, the newly allocated additional uplink channel itself can be released (deallocation). There is an advantage that the use efficiency of the radio resource is increased by opening the channel flexibly according to the flow rate. On the other hand, for a wireless terminal that has released a channel, it cannot continue to secure resources, and it is unclear whether or not the bandwidth (that is, reacquisition of released resources) can be secured when the flow rate increases again. There are disadvantages. Considering this merit, demerit, and radio resource consumption status, whether the additional uplink side channel is released or the transmission is temporarily stopped while the channel is secured. Can be determined. Note that the base station needs to negotiate with the wireless terminal for new allocation, stop and release of the “additional uplink side channel”, which will be described later.

  As described above, the mode in which only the uplink side channel is added, stopped, or released has been described, but the downlink side channel is also added, stopped, or released in the same manner. It is possible to Furthermore, it is also possible to stop or release only one communication channel among the bidirectional communication channels that have been allocated once, regardless of the uplink side or the downlink side. That is, the present invention can be applied to a communication apparatus that operates with an asymmetric channel number in the communication direction regardless of the uplink side or the downlink side.

  As described above, the communication unit 110 establishes communication on the bidirectional communication channel and communication on the unidirectional communication channel between the counterpart communication device and the own device. The feedback information acquisition unit 130 acquires feedback information for a signal transmitted from the counterpart communication device to the local device via the unidirectional communication channel established by the communication unit 110 and received by the reception unit 110R of the communication unit 110. . The control unit 120 controls the transmission unit 110T of the communication unit 110 to transmit the feedback information for the unidirectional communication channel acquired by the feedback information acquisition unit 130 to the counterpart communication device via the bidirectional communication channel. .

  The storage unit 140 associates the bit pattern of the type field of the signal exchanged between the partner communication apparatus and the own apparatus with the position of the feedback information for the unidirectional communication channel in the exchanged signal. Store table TB1. Control unit 120 transmits communication unit 110 so as to transmit a signal in which feedback information for the unidirectional communication channel is arranged at a position corresponding to the correspondence in table TB1 to the counterpart communication device via the bidirectional communication channel. The unit 110T is controlled.

  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 slots of symmetric 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 and the downlink slot, one time distribution is 817 μsec, and three uplink slots are continuous. A guard time between the uplink and the downlink is provided behind the uplink slot, and a group of downlink slots follows.

  The first uplink slot and the first downlink slot are paired to form one bidirectional communication 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 the table below. 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 logical channel resources from 2ch to 4ch and 6ch to 12ch, monitors traffic channel establishment requests from wireless terminals in 5ch, and allocates channel resources to traffic channels The types of channel signals exchanged between the station and the wireless terminal are as shown in the table below.

  The wireless terminal has a wireless terminal ID uniquely assigned by the system, and puts the wireless terminal ID on information symbols of all uplink channels. The base station manages the wireless terminal based on the wireless terminal ID. When the wireless terminal includes the wireless terminal ID in the downlink channel from the wireless base station, the wireless terminal determines whether the wireless terminal ID is addressed to the wireless terminal. To do.

  The broadcast information channel (signal) has a known training sequence pattern and a known information symbol that is unique for each base station ID, and transmits the broadcast information channel every other frame. The wireless terminal monitors logical channel 1 and starts capturing received signals from the point of steep increase in energy, and examines the correlation with known information symbols of multiple possible base station IDs. The base station ID is determined to be the broadcast information channel (signal) of the base station, and the base station ID and timing are stored. After receiving the broadcast information channel signal, the wireless terminal adjusts the reception slot position and tries to synchronize with the base station. 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 begins with the wireless terminal transmitting a traffic channel start request channel signal. The pattern of the training sequence is unique for each base station ID. Also, there are three types of training sequence patterns 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 opened 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 an uplink slot addition request signal when the flow rate exceeds the capacity of the traffic channel. When the traffic channel is open, the base station checks the flow rate of the downlink user data, and if the flow rate is larger than the currently open traffic channel and receives an uplink slot addition request signal from the wireless terminal, It is checked whether or not 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. When the downlink user data flow rate is large and the traffic channel is free, the free channel is reserved as a bidirectional traffic channel for addition to the wireless terminal, and the base station transmits the traffic channel to the wireless terminal. A traffic channel addition permission channel (signal) is transmitted with a number assigned.

  When the downlink user data flow rate is low, the uplink slot addition request signal is received, and the traffic channel is empty, the empty channel is used as an uplink direction traffic channel for addition with the wireless terminal. In addition to making a reservation, the base station assigns a traffic channel number to the wireless terminal and transmits an uplink slot addition permission channel (signal). Alternatively, if there is no available traffic channel, the addition of the traffic channel is abandoned.

  When receiving the uplink slot addition permission channel (signal), the wireless terminal recognizes that the unidirectional traffic channel only in the uplink direction has been established, and does not turn on the LNA switch when receiving the traffic channel next time. Take control. When the traffic channel is open, the base station examines the flow rate of the downlink user data and estimates whether the flow rate is greater than the currently open traffic channel. When it is estimated that it is large, or when a traffic channel addition request signal is received from a wireless terminal, it is determined whether or not a traffic channel of a traffic channel number to which a time slot not currently used with the wireless terminal belongs is free. inspect.

  If the traffic channel is free and a traffic channel addition request signal is received from the wireless terminal, the free channel is reserved for the wireless terminal, and the base station gives the traffic channel number to the wireless terminal. Then, a traffic channel addition permission channel (signal) is transmitted. If there is a free traffic channel number with the same carrier number as the traffic channel that is currently open with the wireless terminal in the free traffic investigation, the traffic channel with the carrier number is used preferentially. Take control.

  If the traffic channel is free and no traffic channel addition request signal has been received from the wireless terminal, the free channel is reserved for the wireless terminal, and the base station gives the traffic channel number to the wireless terminal. Then, a downlink slot addition instruction channel (signal) is transmitted. If there is a free traffic channel number with the same carrier number as the traffic channel currently open with the wireless terminal in the inspection of the empty traffic, the traffic channel with the carrier number is preferentially used. Take control. If the traffic channel is not empty, the addition of the traffic channel is abandoned.

  When receiving the downlink slot addition instruction channel (signal), the wireless terminal transmits a downlink slot addition confirmation channel (signal) to the base station. After that, it recognizes that the unidirectional traffic channel only in the downlink direction has been established, and performs control not to turn on the switch of the transmission power amplifier at the traffic channel transmission from the next time.

  Next, channel signals exchanged between the base station and the wireless terminal will be described in detail. FIG. 5 shows an example of the signal format. As shown in the figure, there is one type of signal format. The header format in the information symbol is common to both the downlink and uplink directions, and includes the fields shown in the following table.

  The header format in an information symbol always includes a type field. The type field is confirmed by checking until 1 appears, with the upper limit being 3 from the first bit. The following table shows the correlation between the bit pattern (identifier) of the type field, the header size, and the subsequent field and its position. This table corresponds to the table TB1 in the storage unit 140 of FIG. The wireless communication apparatus 100 according to the present invention refers to such a correlation table, determines whether or not a proxy Ack serving as feedback information of another unidirectional communication channel is stored, and a position where the proxy Ack is to be stored. Based on this, the proxy Ack is inserted into the packet of another bidirectional communication channel, or the proxy Ack included in the packet received from the communication partner is extracted and used for ARQ.

  FIG. 6 shows four types of formats depending on combinations (bit patterns) of bits in the type field. (A), (b), (c), and (d) in the figure indicate formats 1, 2, 3, and 4, respectively.

  The packet header is followed by a payload. The payload consists of a padding bit string and an octet data string. The padding bit string is a bit string for indicating the start position of octet data, and refers to the first 1 that appears. The MSB (Most Significant Bit) of the first octet data starts immediately after the padding bit string, and the last bit of the entire packet becomes the LSB (Least Significant Bit) of the last octet. The padding bit string changes according to the number of octets to be carried, and the maximum number of octets that can be carried changes according to the header length. Any header can be used without octet data. This is specially called an empty data packet.

  In the sequence number field, the sequence number of the last data is stored as a whole 13 bits. The data to be transported is arranged from the LSB of the subsequent data based on the 119th bit, and the vacant bits are filled with padding bits. The padding bit is a bit string for indicating the head of data, and the next to 1 that appears first after the header is the MSB of the head data. If there is no data to carry, everything is padded with padding bits.

  FIG. 7 shows an information string structure of information symbols for each header format type. (A), (b), (c), and (d) in the figure indicate formats 1, 2, 3, and 4, respectively. As shown, the type field TF1 having the bit pattern “1” is format 1, the type field TF2 having the bit pattern “01” is format 2, the type field TF3 having the bit pattern “001” is format 3, and the bit pattern. Type field TF4 having “000” indicates format 4 respectively. Further, the sequence number is managed independently for each channel, and when the initial communication path is established from the state where the channel is not established, both the transmitting side and the receiving side recognize the initial value of the sequence number as 0. The sequence number of the first data octet is 1.

The transmission side manages the following variables for each channel.
LastSendNum: Sequence number of the last octet of the last packet sent
LastAckPeer: Sequence number returned by the communication partner side Ack The transmission side holds the contents of each transmitted payload from the next sequence number of LastAckPeer to the packet of the sequence number from LastSendNum in correspondence with the transmitted logical frame number. Aside, prepare for retransmission. Since the sequence number is 13 bits, it can represent from 0 to 8191, but the sequence after 8191 is circulated so as to return to 0.

  FIG. 8 shows the sequence number space. In the figure, (a) is a sequence number space on the transmission side, and (b) is a sequence number space on the reception side. Therefore, the sequence number space can be represented by a circle as shown in FIG. Since Ack is 12 bits long, the sequence number (so-called outstanding number) of data that can be transmitted in advance without receiving Ack on the transmitting side is 4096. However, this is an octet data unit.

  The transmitting side complements the MSB so that the 12-bit Ack information from the receiving side is between LastAckPeer and LastSendNum, and reconstructs 13-bit Ack information. Update LastAckPeer with the reconstructed Ack information.

The receiving side manages the following variables.
LastSendAckNum: Sequence number indicating the last octet of data received continuously and without omission
LastReceiveNum: Sequence number indicating the last octet data of the received data The receiving side always stores the lower 12 bits of the current LastSendAckNum as Ack in the Ack field in the header format and returns it to the transmitting side.

  On the data transmission side, it is confirmed whether or not an Ack matching the sequence number of the transmitted data has been returned in the corresponding frame immediately after the elapse of a predetermined round trip time including the decoding time. If the decoding fails or the Ack value of the burst signal received immediately before matches the sequence number of the data transmitted before the round trip time, new data is transmitted in the next frame. Conversely, if the decoding succeeds and the Ack value of the burst received immediately before does not match the sequence number of the data transmitted before the round trip time, it is assumed that the transmission packet is missing, and the sequence indicated by the Ack Resend the data after the number. In this way, a so-called SR type ARQ (Selective Repeat-type ARQ) is realized. This sequence of data transmission and Ack reception is performed for each channel.

  If all channels are only bi-directional channels, both uplink and downlink channels communicate using header format 1. This is the same whether only one bidirectional communication channel is established (that is, a pair consisting of an uplink channel and a downlink channel) or a plurality of bidirectional communication channels are established. FIG. 9 shows a sequence diagram when only “one bidirectional communication channel” is established. As shown in the figure, the wireless terminal TM1 that has received a packet transmitted from the base station BS1 via the downlink channel uses the format 1 and uses the sequence number (seqNum) of the packet itself and LastSendAckNum as feedback information. The packet including the Ack and the data including the data is transmitted to the base station BS1 via the uplink channel paired with the downlink channel. Similarly, the base station BS1 that has received this packet uses the format 1 to transmit the packet including the sequence number (seqNum) of the packet itself, the Ack including LastSendAckNum as feedback information, and the packet including data via the downlink channel. To the wireless terminal TM1.

  FIG. 10 shows a sequence diagram when three bidirectional communication channels exist. As shown in the figure, there are three bidirectional communication channels, ch0, ch1, and ch2. Ack information is transmitted and received independently for each bidirectional communication channel using format 1. For example, feedback information of a packet received via the ch0 uplink communication channel is transmitted from the base station BS1 to the radio terminal TM1 via the same ch0 downlink communication channel. Similarly, feedback information of packets received via the ch1 and ch2 uplink communication channels is also transmitted from the base station BS1 to the radio terminal TM1 via the ch1 and ch2 downlink communication channels.

  When one unidirectional channel is included, header format 2 is used for the unidirectional channel, and header format 1 is used for the unidirectional channel in the bidirectional channel. Also, the header format 3 is used for the channel in the opposite direction to the unidirectional channel in the bidirectional channel. FIG. 11 shows a sequence diagram in the case where one bidirectional channel and one unidirectional channel from the wireless terminal to the wireless base station are established between the base station and the wireless terminal. As shown in the figure, ch0 is a bidirectional channel, and ch1 is a unidirectional (uplink direction) channel from the wireless terminal to the base station. The Ack in the ARQ sequence from the radio terminal to the radio base station in ch1 cannot use ch1. Ack in the ARQ sequence from the radio terminal to the radio base station in ch1 is transmitted by proxy in the header format 3 using a signal from the base station to the radio terminal in ch0. Hereinafter, a proxy Ack for a channel other than the self-paired channel is referred to as a “proxy Ack”. Here, a bidirectional channel in charge of transmission of proxy Ack is a main channel, and a unidirectional channel is a sub channel.

  In this embodiment, it is assumed that there can be up to two subchannels. When two unidirectional channels are included, the header format 2 is used for the unidirectional channel, and the header format 1 is used for the unidirectional channel in the bidirectional channel. In addition, the header format 4 is used for the channel in the opposite direction to the unidirectional channel in the bidirectional channel.

  FIG. 12 shows a sequence diagram when one bidirectional channel and two unidirectional channels from the wireless terminal to the wireless base station are established between the base station and the wireless terminal. As shown in the figure, ch0 is a bidirectional channel, and ch1 and ch2 are unidirectional channels from the wireless terminal to the base station. Ack in the ARQ sequence from the radio terminal to the radio base station in ch1 and ch2 cannot use ch1 or ch2. Ack in the ARQ sequence from the radio terminal to the radio base station in ch1 and ch2 is transmitted by proxy using a signal from the base station to the radio terminal in ch0. That is, the feedback information of the packets received via the ch1 and ch2 uplink communication channels is the header format 4 from the base station BS1 to the radio terminal TM1 via the ch0 downlink communication channel as proxy Ack1 and proxy Ack2. Sent by. The ch0 task (or hardware or circuit) that processes ch0 that is the main channel of the wireless terminal TM1 and the base station BS1 is not the Ack to be processed by the proxy Ack1 or Ack2. Proxy Ack1 and Ack2 are internally transferred to the tasks for ch1 and Ch2 (or hardware and circuits) in charge. In this way, it is possible to make ARQ function normally by transferring the proxy Ack, which is feedback information, between the primary channel task and the secondary channel task using a technique called proxy Ack. .

  There may be two bidirectional channels and one unidirectional channel. In this case, among the bidirectional channels, the channel with the lower number is set as the main channel, and the other bidirectional channel is positioned as the independent channel. The secondary channel uses header format 2 for transmission. Ack that cannot be transmitted on the secondary channel is transmitted as a proxy in header format 3 using the primary channel. In the independent channel, communication is performed using header format 1.

  FIG. 13 is a block diagram showing an outline of the internal configuration of the base station 200 (BS1). 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, ANT2, constituting the adaptive array antenna AAA. Fired from 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. 14 is a block diagram showing 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 synthesis / separation unit 220 for carrier 0 has two spatial multiplexing arithmetic units SP1 spatial multiplexing arithmetic units (SP1_TX-FPGA) 220SP1, 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. 15 is a block diagram illustrating an 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 control unit 230 is connected to the carrier 0 IF signal synthesis / separation unit 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 reception IF (intermediate frequency) signal that the carrier 0 channel control unit 230 receives from the carrier 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 carrier 0 channel control unit 230 applies the received IF (intermediate frequency) signal to the matched filter (MF1) MF1-6, and passes it to the Rzz diagonal term calculation processing unit RZ. The Rzz diagonal term calculation processing unit RZ prepares for calculating a correlation with known training by calculating a covariance matrix for each of 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 TxB1 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 advantage of using an antenna array in the TDMA-TDD system is that the antenna weight estimated by uplink reception is used as the antenna weight of the downlink as it is, and appropriate downlink radio waves are emitted to the same radio wave propagation path. Be able to. 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. 16 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, a transmission stop / start management unit 244, and a header format determination unit 245. The flow management unit 241 associates a user session with a traffic channel. The channel assignment 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 the 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 (signal) is transmitted. When the wireless terminal receives the downlink slot stop instruction channel (signal), the wireless terminal transmits a downlink slot stop response instruction channel (signal) and performs control not to turn on the LNA switch when receiving the traffic channel next time. Do.

  The user data for each traffic channel passed from the channel control unit interface B3 is passed to the flow management unit 241. The sequence number and Ack of the received data are passed to and managed by ARQ sequence management units 241A1, A2,... A8 provided in the flow management unit 241. The flow management unit 241 combines received data from a plurality of traffic channels and converts the received data into received user data.

  Transmission data from an upper layer of an arbitrary user session is distributed to a traffic channel used by the user session. The flow management unit 241 transmits user data corresponding to the carrier number and the spatial multiplexing number to the downlink flow rate monitoring unit 243 for each time slot timing of the traffic channel. At this time, the ARQ sequence management units 241A1, A2,... A8 prepared for each user session manage the sequence numbers and add a header for each signal. The header format determination unit 245 determines the header format according to the situation such as the presence or absence of proxy Ack, and assigns each header corresponding to each format, which will be described later with reference to a flowchart.

  Next, a case where only the channel in the downlink direction is added will be described. When the downlink flow rate monitoring unit 243 determines that an additional downlink is necessary, the flow management unit 241 checks whether or not a traffic channel on the same frequency carrier as the currently used traffic channel is available. If it exists, a downlink slot addition instruction channel (signal) including the designated traffic channel number is transmitted to the wireless terminal. When receiving the downlink slot addition instruction channel (signal), the wireless terminal transmits a downlink slot addition confirmation channel (signal) to the base station.

  When the flow management unit 241 in the base station receives the downlink slot addition confirmation channel (signal), the traffic stop number and spatial multiplexing number included in the downlink slot addition confirmation channel (signal) are transmitted to the transmission stop / start management unit 244. The traffic channel number and the spatial multiplexing number of the traffic channel having the same carrier number as the traffic channel are set.

  When there is a traffic channel only for the downlink slot, the transmission stop / start management unit 244 sends the time slot number, the spatial multiplexing number, and the antenna weight of the traffic channel only for the downlink slot to the channel control unit. Notify the diverted time slot number and spatial multiplexing number.

  When the above processing can be aggregated on the same frequency channel, it is managed by storing it in the prepared aggregate number changeable flag. Whether it is an aggregate in the same channel can be recognized on both the base station side and the wireless terminal side, and is stored in each. The target of this process is to collect data on the same carrier when performing aggregation, but when there is no open traffic channel on the same carrier, control is performed to allocate traffic channels of other carriers.

  Next, the configuration of a wireless terminal that is a communication partner of the base station described above will be described. FIG. 17 is a block diagram showing a configuration of wireless terminal 300 (TM1, TM2). 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 CIR, 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 reception stop / start management unit 320, a baseband processing unit 330, a flow management unit 340, a header format determination unit 350, a channel allocation management unit 360, and an uplink flow rate monitoring unit 370 are further included.

  A wireless terminal has only one antenna. 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. 17, the internal configuration of the wireless terminal 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 at an arbitrary time slot number, the received signal received from the antenna is amplified by the LNA. Prior to reception, the baseband processing unit 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 sequence number and Ack of the received data are transferred to and managed by the ARQ sequence management unit 340A provided in the flow management unit 340. The flow management unit 340 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 to the baseband processing unit as the traffic channel of the time slot. At this time, the ARQ sequence management unit 340A manages the sequence number and adds a header for each signal.

  The flow management unit 340 associates a user session with a traffic channel. Since there can be up to 3 traffic channels for a user session, the association is 1 to 1 to 1 to 3. The channel assignment management unit 360 stores the usage status of the 20 spatially multiplexed traffic channels, and performs control for assigning free traffic channels when new traffic is added.

  User data is divided when a plurality of traffic channels are used. Further, 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.

  It is assumed that a traffic channel can have a maximum of three for one user session. A separate traffic channel is used for each time slot. Now assume that one traffic channel is open between the base station and the wireless terminal and that additional traffic is required only in the uplink direction. The amount of uplink data traffic is large, and two traffic channels are required. However, if the base station determines that one traffic channel is sufficient for the downlink data flow, open two traffic channels. In this case, the downlink traffic channel has no data to carry and will send empty data packets. 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 realize this, control for adding transmission only in the uplink direction is performed.

  As described above, the radio terminal can stop the radio wave emission in the downlink direction when the uplink traffic is large but the downlink traffic is small. 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. Increase usage efficiency.

  The traffic channel is shared among wireless terminals connected to other spatial multiplexing of 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 realize this, control is performed to stop transmission in the uplink direction.

  When the aggregate number changeable flag is on, the radio terminal can stop the radio wave emission in the uplink direction when the downlink traffic is large but the uplink traffic is small. As a result, unnecessary radio wave emission can be reduced, and interference in the uplink 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. Use efficiency can be increased.

  Further, the wireless terminal can obtain an effect of battery saving by preventing emission of unnecessary radio waves. In a wireless terminal, the current consumption of the power amplifier is often dominant with respect to the overall current consumption, and reducing the time during which the power amplifier switch is on as much as possible contributes to battery saving. If the transmission of the radio wave in the uplink direction of one traffic channel is omitted while using two traffic channels, the current consumption of the power amplifier can be halved.

  With the above processing, the base station can add a downlink direction traffic channel and not emit an uplink direction radio wave emission when there is much downlink traffic but little uplink traffic. As a result, unnecessary radio wave emission can be reduced, and interference in the uplink 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. Use efficiency can be increased.

  When an additional unidirectional traffic channel becomes unnecessary, a downlink slot stop instruction is transmitted from the base station to the wireless terminal. As a result, the additional traffic channel can be stopped. After receiving the downlink slot stop instruction, the wireless terminal transmits a downlink slot stop confirmation to the base station and recognizes that the unidirectional traffic channel is closed.

  By forming an asymmetric number of channels on the uplink and downlink through the above processing, unnecessary emission of radio waves can be eliminated. In order to realize SR-type ARQ in such an uplink / downlink asymmetric number of channels, header format determination units 245 and 350 are added. The header format determination units 245 and 350 determine the header format by performing processing shown in the following flow according to the number of subchannels to be transmitted or received. The operations of the header format determination units 245 and 350 are common to the base station 200 and the wireless terminal 300.

  The ARQ sequence management units 241A1 to A8 and 340A construct a header according to the format determined by the header format determination units 245 and 350. In this way, even in a unidirectional channel in which Ack cannot be returned, Ack transmission is realized by carrying Ack on behalf of the main channel.

  FIG. 18 is a flowchart showing a header format selection process when a signal is transmitted to the counterpart communication device. This header format selection process is executed by the header format determination units 245 and 350 of the base station 200 and the radio terminal 300. The header format type added to the head of the received signal is examined, and the type of header format is determined. This is a process of determining whether or not and assigning a header according to the determination result. As shown in the figure, in step S1, it is determined whether or not there is a subchannel to be transmitted (that is, a unidirectional communication channel in the direction from the own apparatus to the other communication apparatus). If there is a subchannel to be transmitted, it is determined whether or not the current transmission is the timing of the transmission subchannel (step S12). If the subchannel is to be transmitted, the header format 2 is selected (step S12). S14) If not, the header format 1 is selected (step S13), and the process ends.

  If it is determined in step S1 that there is no subchannel to be transmitted, the process proceeds to step S2 to determine whether there is a subchannel to be received. If there is no secondary channel to be received, the header format 1 is selected and the process is terminated (step S11). If it is determined in step S2 that there is no subchannel to be received, it is determined whether or not the current transmission is at the timing of the main channel (step S3). If it is not the timing of the main channel, the header format 1 is selected in step S11 and the process is terminated. If it is determined that it is the timing of the main channel, it is determined in step S4 whether the number of subchannels is two. If it is determined that the number of secondary channels is not 2, after selecting header format 3 (that is, the format when there is only one secondary channel), the process proceeds to step S8. When it is determined that the number of subchannels is 2, header format 4 is selected (that is, the format when there are two subchannels). Thereafter, in step S6, the logical channel number of the secondary channel 2 is set to the proxy Ack2 channel number. Next, in step S7, the Ack of the secondary channel 2 is set to the other channel proxy Ack2. In step S8, the logical channel number of the secondary channel 1 is set to the proxy Ack1 channel number. Next, in step S9, the Ack of the secondary channel 1 is set to the other channel proxy Ack1, and the process is terminated.

  FIG. 19 is a flowchart showing signal processing when a signal from the counterpart communication device is received. In this process, the type of header format is determined by examining the beginning (type field) of the received data. As shown in the figure, in step S21, it is determined whether or not the top of the received data is 1. If it is determined that the head is 1, the received data is considered to be in header format 1, the sequence number and Ack are separated from the received data (step S30), and the process ends. When it is determined in step S21 that the head is not 1, the process proceeds to step S22, and it is determined whether or not the head of the received data is 01. If it is determined that the head is 01, the received data is considered to be in header format 2, the sequence number is separated from the received data (step S29), and the process ends. If it is determined in step S22 that the head is not 01, the process proceeds to step S23, and it is determined whether or not the head of the received data is 001. If it is determined that the head is 001, the received data is assumed to be in header format 4, and the sequence number, Ack, proxy Ack1 channel number, other channel proxy Ack1, proxy Ack2 channel number, other channel proxy are determined from the received data. Separate Ack2. In step S27, the contents of the other channel proxy Ack1 are stored as Ack for the traffic channel corresponding to the proxy Ack1 channel number. Next, in step S28, the contents of the other channel proxy Ack2 are stored as Ack for the traffic channel corresponding to the proxy Ack2 channel number, and the process ends.

  As described above, when the proxy Ack channel number and other channel proxy Ack are included in the header, the primary channel is used as the proxy even if the unidirectional channel cannot return the Ack by recognizing it as the Ack for the corresponding traffic channel. As Ack can be carried. Thus, even in a transmission path in which the number of channels in each direction is asymmetric, automatic retransmission control by ARQ is realized, and a highly reliable transmission path can be realized.

  In the above configuration example, format 2 is used for the subchannel to be transmitted, but since format 2 does not require an Ack field, it can carry much user data accordingly. That is, a signal using header format 1 can carry 11 octets, whereas header format 2 can carry 13 octets. Therefore, when two channels are established, if one channel is set to header format 2 compared to the case where header format 1 is assigned to two channels, (((13 * 8) + (11 * 8) )-((11 * 8) + (11 * 8))) * (1 / 0.05) = 3200bps throughput improvement. As a trade-off, throughput in the opposite direction is reduced because header format 3 is used. (Header format 3 can only carry 9 octets.) However, in a state where there is a secondary channel to be received, there is no data to be transmitted or there is little data, so a decrease in throughput is not a problem.

  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. For example, although the present invention has been described in a form using a wireless communication device in the embodiments, the present invention can also be applied to a wired communication device, and the wired communication device, method, and system are also within the scope of the present invention. It should be understood that it is included.

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 an example of a signal format. It is a figure which shows four types of formats by the combination (bit pattern) of the bit of a type field. It is a figure which shows the information sequence structure of the information symbol for every header format type. It is a figure which shows sequence number space. It is a sequence diagram in case only one bidirectional communication channel is established. It is a sequence diagram in case three bidirectional communication channels exist. It is a sequence diagram when one bidirectional channel and one unidirectional channel from the wireless terminal to the wireless base station are established between the base station and the wireless terminal. It is a sequence diagram when one bidirectional channel and two unidirectional channels from the wireless terminal to the wireless base station are established between the base station and the wireless terminal. It is a block diagram which shows the outline of an internal structure of the base station 200 (BS1). 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. It is a block diagram which shows the structure of the radio | wireless terminal 300 (TM1, TM2). It is a flowchart which shows the header format selection process in the case of transmitting a signal to the other party communication apparatus. It is a flowchart which shows the signal processing at the time of receiving the signal from the other party communication apparatus.

Explanation of symbols

AA, AAA Adaptive array antenna ADC, ADC1 Analog to digital converter ANT1, ANT2, ANT3, ANT4, ANT5, ANT6, ANT10 Antenna TB table TB1 Channel allocation table TB2 Reference flow rate table 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 monitoring unit IF-PLL IF phase lock loop LNA Low noise amplifier MX1, MX2, MX3, MX4, MX5, MX6 Mixer PA Power amplifier RF-PLL RF phase lock loop RF1-6 RF unit RxB1, RxB2 SP1, SP2 reception baseband processing for each antenna Processing unit TxB1, TxB2 SP1, SP2 Transmission baseband processing unit RZ Rzz diagonal term calculation processing unit SG Signal generator TM1, TM2 Wireless terminal TS1, TS2 Training sequence generation unit TSM1, TSM2 Transmission stop information storage unit UL, UL1, UL2 , UL8 Upper layer VCTCXO Temperature compensation voltage control crystal oscillator W1-6 Antenna weight control unit WC1, WC2 SP1, SP2 weight calculation unit WD1, WD2 SP1, SP2 weight determination unit WR Wait register 200 Base station 210 Timing processor 220 IF for carrier 0 Signal synthesis / separation unit 221 Carrier 1 IF signal synthesis / separator 222 Carrier 2 IF signal synthesis / separation unit 223 Carrier 3 IF signal synthesis / separation unit 220RF RF arrays 220SP1, SP2 SP1, SP2 Operation unit 230 Channel control unit for carrier 0 231 Channel control unit for carrier 1 232 Channel control unit for carrier 2 233 Channel control unit for carrier 3 240 Main control unit 241 Flow management unit 241A1-A8 User1-8_ARQ sequence management unit 242 Channel allocation Management unit 243 Downlink flow rate monitoring unit 244 Transmission stop / start management unit 245 Header format determination unit 300 Wireless terminal 310 Timing processor 320 Reception stop / start management unit 330 Baseband processing unit 340 Flow management unit 340A Sequence management unit 350 Header format determination Unit 360 channel allocation management unit 370 uplink flow rate monitoring unit CIR circulator

Claims (9)

In the communication device that performs communication between the partner communication device and its own device,
A communication unit that establishes communication in a bidirectional communication channel and communication in at least one unidirectional communication channel between the counterpart communication device and the own device; and
A feedback information acquisition unit for acquiring feedback information for a signal transmitted from the counterpart communication device to the own device via the at least one unidirectional communication channel established by the communication unit and received by the communication unit;
A control unit that controls the communication unit to transmit feedback information for the at least one unidirectional communication channel acquired by the feedback information acquisition unit to the counterpart communication device via the bidirectional communication channel; ,
A communication device comprising: The communication device according to claim 1,
A memory for storing a table in which an identifier of a type field of a signal exchanged between the counterpart communication device and the own device is associated with a position in the exchanged signal of feedback information for a unidirectional communication channel Further comprising
A communication device. The communication device according to claim 2,
The control unit is
The communication unit is configured to transmit a signal in which feedback information for the at least one unidirectional communication channel is arranged at a position corresponding to the correspondence of the table to the counterpart communication device via the bidirectional communication channel. Control,
A communication device. The communication device according to claim 2,
A plurality of the unidirectional communication channels;
The control unit is
The feedback information in each of the plurality of unidirectional communication channels is transmitted to the counterpart communication device via the bidirectional communication channel, with the signals arranged at positions corresponding to the correspondence of the table. Control the communication part,
A communication device. In a communication system that performs communication between a first communication device and a second communication device,
The first communication device is
A communication unit that establishes communication in a bidirectional communication channel and communication in at least one unidirectional communication channel between the second communication device and the own device; and
A feedback information acquisition unit for acquiring feedback information for a signal transmitted from the second communication device to the own device and received by the communication unit via the at least one unidirectional communication channel established by the communication unit; ,
A control unit that controls the communication unit to transmit feedback information for the at least one unidirectional communication channel acquired by the feedback information acquisition unit to the second communication device via the bidirectional communication channel. And
The second communication device is
A communication unit that establishes communication in a bidirectional communication channel and communication in at least one unidirectional communication channel between the first communication device and the own device; and
Receiving a signal transmitted from the first communication device via the bidirectional communication channel and including feedback information for the at least one unidirectional communication channel, and depending on the information included in the received signal, the at least A control unit that controls the communication unit to adaptively adjust a modulation scheme of one unidirectional communication channel;
A communication system characterized by the above. The communication system according to claim 5, wherein
The first communication device is
Stores a table in which the identifier of the type field of the signal exchanged between the second communication apparatus and the own apparatus is associated with the position of the feedback information for the unidirectional communication channel in the exchanged signal. Further comprising a storage unit,
A communication system characterized by the above. The communication system according to claim 6,
The control unit in the first communication device is
The communication unit is configured to transmit a signal in which feedback information for the at least one unidirectional communication channel is arranged at a position corresponding to the correspondence of the table to the second communication device via the bidirectional communication channel. To control the
A communication system characterized by the above. In the communication system according to any one of claims 5 to 7,
The second communication device is
The type field identifier of the signal exchanged between the first communication device and the second communication device is associated with the position of the feedback information for the unidirectional communication channel in the exchanged signal. A storage unit for storing the table;
The control unit in the second communication device is
Referring to the table, feedback information for the at least one unidirectional communication channel is acquired from the received signal, and a modulation scheme of the at least one unidirectional communication channel is adaptively determined according to the acquired information To adjust,
A communication system characterized by the above. In a communication method of performing communication using an adaptive modulation method between a first communication device and a second communication device,
Communication in which the first communication device establishes communication on the bidirectional communication channel and communication on at least one unidirectional communication channel between the second communication device and the own device. Steps,
Feedback information of a signal transmitted from the second communication apparatus to the own apparatus through the at least one unidirectional communication channel established by the communication step and received by the communication unit. A feedback information acquisition step to acquire,
The first communication device transmits feedback information for the at least one unidirectional communication channel acquired in the reception signal quality acquisition step to the second communication device via the bidirectional communication channel. Control steps to control,
The second communication device receives a signal transmitted from the first communication device via the bidirectional communication channel and including feedback information for the at least one unidirectional communication channel, and responds to the received signal. A control step for controlling to adaptively adjust a modulation scheme of the at least one unidirectional communication channel;
A communication method characterized by comprising:

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