JP2007184940A - Method and apparatus for resource allocation in relay-based cellular configuration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve system throughput and channel utilization rate by effectively utilizing a resource allocation gain that may result from spatial independency. <P>SOLUTION: A method of resource allocation in relay-based cellular configuration according to the present invention includes: at a mobile terminal accessing a network, judging whether the terminal itself is a single-hop user or a double-hop user by monitoring notification information from a base station and a relay station in the network, further judging which relay station's coverage the terminal itself belongs to if the terminal is the double-hop user, and feeding the information of the relay station to which the terminal itself belongs back to the base station via the relevant relay station; at the base station, allocating a channel to the current mobile terminal; and between the base station and the mobile terminal, then transmitting data via the relay station to which the relevant mobile terminal belongs, using the allocated channel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resource allocation technique in a communication system, and more particularly, to a relay-based cellular resource allocation method, and a mobile communication system and a relay station using the resource allocation method.

  Future cellular networks have features such as high data rates and wide coverage. A request for the data rate to reach 1 Gbps for low-speed or stationary users and 100 Mbps for high-speed mobile users based on the requirements of the International Telecommunications Union Radiocommunication Division (ITU-R) M1645 document. Has been. Assuming that the power on the transmitting side is constant, the energy of each transmitted bit is inversely proportional to the data rate to be transmitted. That is, the signal-to-noise ratio Eb / No on the receiving side decreases linearly with the continuous improvement of the data rate. As a result, the receiving side cannot receive the data correctly. This affects cell coverage. The operating frequency band of the third generation mobile communication system (3G) is 2 GHz, but the operating frequency band left in the next generation network is much higher than the operating frequency band of 3G, for example, about 5 GHz. The high operating frequency band causes higher path loss, and the high operating frequency band is more sensitive to fading, thereby promoting the deterioration of cell coverage performance.

  Relay is one of the most effective ways to solve the above problem of cell coverage deterioration. The basic principle of relay is to obtain coverage by exchanging with capacity. Due to resource orthogonality limitations, relay stations cannot simultaneously transmit and receive different signals in the same frequency band and code channel. In other words, the reception and transmission of the relay station must be orthogonal. That is, different signals can be transmitted and received at different times or frequency bands for the relay station. However, due to the effects of perspective, it is generally not permitted to transmit different signals using different code channels.

  Here, the basic principle of the relay will be further described by taking time division duplex and a forward link from the base station to the user as examples. In traditional cellular networks, user-assigned time slots can be used for signal transmission or reception by the base station or user all the time, but in relay-based cellular networks, user-assigned time slots have two parts. It is divided into. Among them, the first part is used for data transmission between the base station and the relay station, and the second part is used for data transmission between the relay station and the mobile terminal. Thus, with constant transmission power, within the same time, the throughput in a relay-based cellular configuration is half that of a traditional network. The above is the basic principle that the relay station acquires coverage by exchanging with the capacity. Relay-based networks can increase cell coverage. In other words, relay-based networks can reduce system power consumption over traditional networks under the same transmission distance conditions. In addition, the relay has advantages such as low cost and easy installation. Specifically, since the relay facility is simpler than the base station facility, the cost of the base station itself is reduced. Note that the cost of network expansion is further saved because the relay station and the base station are connected by a wireless link and do not require an optical fiber network.

  FIG. 1 is a diagram showing a cellular configuration including four relay stations. In FIG. 1, an access point (AP) generally refers to a base station in a cellular configuration, each mobile terminal (MT, Mobile Terminal) represents each user, and a fixed relay station station (FRS) as a relay station. , Fixed Relay Station) realizes data relay between AP and MT. In general, relay-based cellular systems include one-hop users and two-hop users. Here, the one-hop user is a user who can be directly covered by the base station, and can directly communicate with the base station without being relayed by the relay station. For example, MT5, MT6 and MT7 in FIG. Two-hop users are users located outside the coverage of the base station, and for these users, communication with the base station can be performed only by relaying of the relay station. For example, MT1, MT2, MT3, MT4, MT8, MT9, MT10 and MT11 in FIG.

  In the following, taking a time division multiple access (TDMA) system with a fixed time slot length as an example, it is assumed that the mobile terminals are evenly distributed in the cell at the same time. The channel allocation method in the relay-based cellular configuration is introduced.

  In the first channel allocation method, the base station and each relay station provide services to each user in turn. As shown in FIG. 2, in such a channel allocation method, a TDMA frame used for data transmission includes four long time slots and one short time slot. Within the four long time slots, the base station sequentially performs data transmission with the two-hop users covered by each relay station via the relay station. Within the short time slot, the base station performs data transmission with a one-hop user (eg, MT5) within its coverage. Here, each long time slot further includes two short slots of the same length. Among them, one short time slot was used for data transmission between the base station and the relay station, also called one-hop time slot, and another short time slot was covered by the relay station and this relay station It is used for data transmission with users and is also called a two-hop time slot. As can be seen from the above method, since the channel resource is not reused in this channel allocation method, the system throughput and the channel utilization rate are very low.

  The second channel allocation method is based on the following assumptions. That is, in an urban environment, two adjacent relay stations are separated from each other by a building, so that data transmission with a mobile terminal covered by the relay station can be performed simultaneously. For example, assume that there are buildings between FRS1 and FRS2 and between FRS3 and FRS4, respectively, and that FRS1 and FRS2 and FRS3 and FRS4 can each transmit data simultaneously. In this case, as shown in FIG. 3, the TDMA frame format used for data transmission includes a total of seven fixed-length short time slots. Here, in the previous four short time slots, the base station sequentially performs data transmission with each relay station. Two adjacent relay stations FRS1 and FRS2 simultaneously perform data transmission with the two-hop users covered by each of them in the fifth short time slot. The other two adjacent relay stations FRS3 and FRS4 simultaneously perform time slot transmission with the two-hop users covered by each other within the sixth short time slot. The seventh short time slot is used for data transmission between the base station and the one-hop user covered by this base station. As can be seen, this method provided a certain improvement in system throughput and channel utilization.

  In the third channel allocation method, the concept of smart antenna and multi-channel is further introduced on the assumption of the second channel allocation method. As shown in FIG. 4, in such a channel allocation method, the TDMA frame format used for data transmission includes a total of two fixed-length time slots. Among them, in the first short time slot, the base station occupies three frequency bands using a smart antenna and transmits data to four relay stations in parallel. Within the second short time slot, two adjacent relay stations, for example FRS1 and FRS2 and FRS3 and FRS4, each occupy one frequency band and the base station occupies one frequency band and Send data in parallel to two-hop or one-hop users covered by.

  In the following, referring to FIG. 1, channel allocation methods in three other conventional relay-based cellular configurations are introduced with reference to FIG. 1, taking a time division multiple access (TDMA) system with a variable time slot length as an example. Similarly, it is assumed that the mobile terminals are uniformly distributed in the cell.

  In the fourth channel allocation method, the base station and each relay station provide services to each user in turn. As shown in FIG. 5, the TDMA frame used for data transmission includes four long time slots and one short time slot, and the contents carried in each time slot are the same as the frame configuration shown in FIG. is there. However, in FIG. 5, the lengths of the two short time slots included in each long time slot are not equal. The purpose is to ensure approximately the same amount of traffic between the base station and the relay station in the previous short time slot and the communication traffic between the relay station and the mobile terminal in the subsequent short time slot. Since the relay station is affected by various factors such as the receiving antenna gain, generally, if the same amount of information is alternated, the throughput between the base station and the relay station is larger than the throughput between the relay station and the mobile terminal. The data transmission time between the relay station and the relay station is less than the data transmission time between the relay station and the mobile terminal. Therefore, on the premise of maintaining roughly the same throughput, in each long time slot, the length of the first short time slot is usually smaller than the length of the second short time slot. Here, since the channel resource is not reused in the fourth channel allocation method as in the first channel allocation method, the system throughput and the channel utilization rate are also very low.

  Corresponding to the second channel allocation method, the fifth channel allocation method is also based on the following assumptions. That is, in an urban environment, two adjacent relay stations are separated from each other by a building, so that transmission from the relay station to the mobile terminal can be performed simultaneously. In this case, as shown in FIG. 6, the TDMA frame format used for data transmission also includes a total of seven short time slots, and the contents carried in each time slot are the same as the frame configuration shown in FIG. is there. Compared to FIG. 3, the only difference is that the lengths of the seven short time slots shown in FIG. 6 are not the same. Here, the length of the short time slot occupied for data transmission between the base station and the relay station is much longer than the short time slot occupied for data transmission between the relay station and the mobile terminal and between the base station and the mobile terminal. small.

  In the sixth channel allocation method, the concept of smart antenna and multi-channel is further introduced on the assumption condition of the fifth channel allocation method. The TDMA frame format used for data transmission is almost the same as the frame format shown in FIG. The only difference is that the length of the first short time slot therein is generally less than the length of the second short time slot.

  As can be seen from the above method, in the conventional second, third, fifth and sixth channel allocation methods, channel reuse was performed, but there was a spatial independence link in the relay-based cellular configuration. Since the intrinsic property was not utilized, the resource allocation gain that can be brought about by this spatial independence cannot be used effectively. As a result, a certain amount of system resources is wasted.

  To solve the above technical problem, the present invention can take full advantage of the inherent property that there is a spatial independent link in relay-based cells, and the space that can be provided by this spatial independence. A method is provided for performing resource allocation in relay-based cells that improves system throughput and channel utilization by effectively utilizing space diversity gain.

  In order to realize the resource allocation method in the relay-based cellular configuration of the present invention, the present invention provides a relay-based cellular mobile communication system to which the method is applied and a relay station used in the system. This allows resource allocation to take advantage of the essential property of spatial independent links in relay-based cellular networks, further increasing system throughput and channel utilization.

In accordance with one aspect of the present invention, a resource allocation method in a relay-based cellular configuration according to the present invention includes:
A mobile terminal accessing the network monitors broadcast information from the base station and all relay stations in the network to determine whether it is a one-hop user or a two-hop user, and If it is determined that it is a hop user, it determines which relay station it belongs to based on the received broadcast information, and relay station information to which it belongs to the base station via the relay station. Feedback step a,
The base station assigns a channel to the current mobile terminal based on resource allocation rules, and instructs the mobile terminal to the assigned channel via a relay station to which the mobile terminal belongs;
A step c in which the base station and the mobile terminal perform data transmission using an allocated channel.

Monitoring broadcast information from the base station and all relay stations in the network in step a,
Step a1 in which the base station periodically broadcasts broadcast information through a broadcast channel;
After the relay station in the coverage of the base station receives the broadcast information broadcasted by the base station, step a2 for forwarding the broadcast information from the base station to the mobile terminal in the coverage;
Step a3 in which the mobile terminal accessing the network receives broadcast information transmitted by the base station and broadcast information transferred by the relay station.

Whether the mobile terminal is a one-hop user by measuring the signal-to-interference power and noise ratio or received power of broadcast information from the received base station and all relay stations in the network in step a Or if you ’re a two-hop user,
Specifically, the determination in step a is as follows:
Step a4 in which the mobile terminal measures the signal-to-interference power and noise ratio of the broadcast information from the received base station and all relay stations in the network;
Search for broadcast information having the maximum signal-to-interference power and noise ratio from among them, and if the broadcast information is from a base station, the mobile terminal determines that it is a one-hop user, If the broadcast information is from a relay station, the mobile terminal includes step a5 for determining that the mobile terminal is a two-hop user.

  In step a, the mobile terminal that determines to which relay station the mobile terminal belongs belongs to the broadcast station based on the relay station characteristic information attached to the broadcast information having the maximum signal-to-interference power and noise ratio. The relay station that transferred the information is identified, and it is determined that it belongs to the coverage of the relay station.

  The feature information is information on different times and / or code channels and / or channels used when each relay station broadcasts.

  The resource allocation rules in step b include assigning the same channel only to mobile terminals belonging to the coverage of different relay stations, and assigning the same channel to at most two mobile terminals.

Assigning a channel to the current mobile terminal in step b
When the base station searches for and finds a channel resource of a relay station different from the relay station to which the mobile terminal belongs in the channel resource allocation table of the cell based on the relay station to which the mobile terminal belongs, If b12 is executed and not found, step b11 is executed to execute step b13;
It is determined whether there is a channel resource that can be reused in the found channel resource. If there is one, a channel that can be reused is allocated to the mobile terminal, and the channel resource allocation table of this cell is updated. If not, step b12 for executing step b13;
Assigning a channel to the current mobile terminal and updating the channel resource assignment table of this cell; b13.

  The resource allocation rule further includes allocating a channel closest to the signal-to-interference power and noise ratio of a currently accessed mobile terminal when there is one or more reusable channel resources.

The method
The relay station periodically measures the signal-to-interference power and noise ratio from the base station to the relay station, and periodically measures the signal-to-interference power and noise ratio from the relay station to each mobile terminal measured by the mobile terminal. Receiving and reporting to the base station,
Based on the signal-to-interference power and noise ratio reported by the relay station, the base station updates the channel resource information occupied by each mobile terminal in the intra-cell channel resource allocation table recorded by itself. And further including
In step b, allocating a channel to the current mobile terminal
Based on the relay station to which the accessed mobile terminal belongs, the channel resource allocation table is searched for a channel resource possessed by a relay station different from the relay station to which the mobile terminal belongs, and such a channel resource is obtained. If found, execute step b22; if not found, execute step b24;
It is determined whether there is a channel resource that can be reused in the found channel resource, and if there is, step b23 is executed; otherwise, step b22 is executed;
It is determined whether there are one or more reusable channel resources, and if there are, the signal-to-interference power and noise ratio of the reusable channel resources and the signal pair corresponding to the currently accessed mobile terminal, respectively. Compare the interference power and noise ratio, assign the channel closest to the signal-to-interference power and noise ratio of the currently accessed mobile terminal to the current mobile terminal, and set the channel resource allocation table for this cell. If not updated, step b23 for allocating the reusable channel to the currently accessing mobile terminal and updating the channel resource allocation table of this cell;
B24 which allocates a channel to the current mobile terminal and updates the channel resource allocation table of this cell.

Specifically, allocating a channel closest to the signal-to-interference power and noise ratio of the currently accessed mobile terminal to the current mobile terminal,

Assigning a channel occupied by a mobile terminal satisfying to the currently accessed mobile terminal,
Where min () function represents minimum value operation, abs () function represents absolute value operation,

Represents the signal-to-interference power and noise ratio in the y-th hop time slot of the mobile terminal currently accessing the network,

Represents the signal-to-interference power and noise ratio in the y-th hop time slot of another mobile terminal of this cell, and the value of y is 1 or 2.

In a time division multiple access system, the channel resource is a time slot;
In step c, the base station and the mobile terminal perform data transmission using an allocated channel,
Two short time slot resources are allocated to two two-hop mobile terminals, and the first short time slot is simultaneously assigned to the first hop time slot and the second mobile of the first mobile terminal in the two mobile terminals. The second hop time slot of the terminal, and the second short time slot simultaneously as the second hop time slot of the first mobile terminal and the first hop time slot of the second mobile terminal. Including.

  The short time slot resource is a basic time slot resource in a time division multiple access system.

  The short time slot resource is a short time slot obtained by dividing a basic time slot in a time division multiple access system into two time slots.

  In the process of data transmission in step c, after receiving the data packet, the relay station should determine whether the currently received data packet should be forwarded by itself and should be forwarded by itself. If so, the data packet is transferred. Otherwise, the data packet is discarded.

  Moreover, based on other parts of the present invention, the present invention provides a relay-based mobile communication system in which each cell includes one base station, one or more relay stations, and a mobile terminal.

Here, the base station records a channel resource allocation table of this cell, allocates a channel to a mobile terminal accessing this cell based on the channel resource allocation table,
The relay station is
An antenna that receives a reception signal from a base station or a mobile terminal when the relay station receives the signal, and transmits a signal waiting for transmission to the base station or the mobile terminal when the relay station transmits;
A receiving element that performs operations such as down-converter, demodulation and decoding on the received signal, and determines whether to transfer the processed data;
A transmitting element that performs encoding, modulation, and up-converter processing on the data that needs to be transferred, processed by the receiving element, and generates a signal waiting for transmission;
A signal waiting for transmission generated by the transmitting element is output to the antenna when the relay station transmits, and a signal received by the antenna is connected to the receiving element when the relay station receives the signal. And a transmission / reception conversion switch that realizes conversion between the transmission and reception functions of the relay station.

The receiving element in the relay station,
A down-converter module that performs down-converter processing on the received signal;
A demodulation module that demodulates the signal after being downconverted by the downconverter module;
A decoding module for decoding the signal demodulated by the demodulation module;
An identification module is further provided for identifying the data obtained after being decrypted by the decryption module and determining whether it is necessary to transfer the data.

The transmitting element in the relay station,
An encoding module for encoding data that needs to be transferred from the receiving element;
A modulation module that modulates the data after being encoded by the encoding module;
And an up-converter module that performs up-converter processing on the signal modulated by the modulation module.

In accordance with another aspect of the present invention, the present invention provides a relay station. The relay station
An antenna that receives a reception signal from a base station or a mobile terminal when the relay station receives the signal, and transmits a signal waiting for transmission to the base station or the mobile terminal when the relay station transmits;
A receiving element that performs operations such as down-converter, demodulation and decoding on the received signal, and determines whether to transfer the processed data;
A transmitting element that performs encoding, modulation, and up-converter processing on the data that needs to be transferred, processed by the receiving element, and generates a signal waiting for transmission;
A signal waiting for transmission generated by the transmitting element is output to the antenna when the relay station transmits, and a signal received by the antenna is connected to the receiving element when the relay station receives the signal. And a transmission / reception conversion switch that realizes conversion between the transmission and reception functions of the relay station.

The receiving element is
A down-converter module that performs down-converter processing on the received signal;
A demodulation module that demodulates the signal after being downconverted by the downconverter module;
A decoding module for decoding the signal demodulated by the demodulation module;
An identification module is further provided for identifying the data obtained after being decrypted by the decryption module and determining whether it is necessary to transfer the data.

The transmitting element is
An encoding module for encoding data that needs to be transferred from the receiving element;
A modulation module that modulates the data after being encoded by the encoding module;
And an up-converter module that performs up-converter processing on the signal modulated by the modulation module.

  As can be seen, the resource allocation method of the present invention and the channel resources that can be reused in the relay-based mobile communication system are allocated to the mobile terminals accessing the network using the resource allocation rules, thereby By taking full advantage of the inherent nature of spatial independent links in existing cellular networks, it is possible to effectively utilize the space diversity gain that can be provided by this spatial independence, improving system throughput. Yes.

  Specifically, in the above method of the present invention, the first hop time slot and the second hop time slot of one mobile terminal and the other mobile terminal of two mobile terminals each covered by two relay stations. By reusing the second hop time slot and the first hop time slot, it is possible to allocate the same channel resource to two mobile terminals, and further to greatly improve the throughput and channel utilization of the system. ing.

  Also, in the fixed time slot length frame format submitted by the above method of the present invention, the time slot length occupied by one hop user is the same as the short time slot length in the long time slot of two hop users. By assuming that each user has the same communication capability with the base station, fairness among users can be ensured when the user distribution is uniform.

  In order to further clarify the objects, technical solutions, and merits of the present invention, the present invention will be described in more detail with reference to the accompanying drawings.

  In order to make full use of the essential property of spatial independent links in relay-based cellular networks and to effectively utilize the space diversity gain that can be provided by this spatial independence, A method for allocating resources in a relay-based cell is provided. As shown in FIG. 7, the method mainly includes the following steps.

  In step A, the mobile terminal accessing the network monitors broadcast information from the base station and all relay stations in the network, and based on the broadcast information monitored, the mobile terminal is directly covered by the base station. It is determined whether the user is a user or a two-hop user covered by a relay station.

  In a relay-based cellular mobile communication system, a base station periodically broadcasts broadcast information through its broadcast channel. The relay station within the coverage of the base station receives the well-known information broadcast by the base station, and then forwards the broadcast information from the base station. Accordingly, in step A, the mobile terminal accessing the network can monitor the broadcast information transmitted by the base station and transferred by the relay station.

  In step A, the mobile terminal receives the signal-to-interference power and noise ratio (SINR, Signal-to-interference-plus-noise Ratio) of the broadcast information received from the base station and all relay stations in the network. Or by measuring the received power, it is determined whether the user is a one-hop user or a two-hop user.

The specific method of judging above is
Step A1 in which the mobile terminal receives SINR of broadcast information received from the base station and all relay stations in the network; and
If the broadcast information having the maximum SINR is searched from among them and it is determined that the broadcast information is from the base station, the mobile terminal determines that it is a one-hop user, and the broadcast information is If it is determined that the mobile terminal is from a certain relay station in the cell, the mobile terminal includes step A2 for determining that the mobile terminal is a two-hop user.

  If it is determined in step B that the mobile terminal is a two-hop user, the mobile terminal further determines which relay station the mobile terminal belongs to based on the received broadcast information, and the relay to which the mobile terminal belongs The station information is fed back to the base station via the relay station to which the station belongs.

  Corresponding to step A, the mobile terminal has the largest SINR in order to add to the broadcast information feature information that the relay station can uniquely identify itself when transferring broadcast information from a base station After finding the broadcast information, it is possible to identify from which relay station the broadcast information is based on the relay station characteristic information attached to the broadcast information. Allows to determine the relay station. After determining the relay station to which the mobile station belongs, the mobile terminal notifies the relay station of the SINR measured by the mobile terminal and the relay station to which the mobile terminal belongs, and the relay station receives it. By transferring the information to the base station, the relay station to which the mobile terminal belongs can be known to the base station.

  Here, the feature information is information such as a different time and / or code channel and / or frequency channel (frequecy channel) that can uniquely identify each relay station used when each relay station broadcasts. OK. With the above feature information, the mobile terminal can easily identify whether the received broadcast information is from the base station or from the relay station, and if it is from the relay station, it is received It is also possible to further determine which relay station the broadcast information is based on the feature information.

  Hereinafter, taking as an example that the feature information is at different times, it will be described in detail how the mobile terminal identifies the source of the received broadcast information by using the feature information indicated at different times. .

  In the broadcast channel, the broadcast information is transmitted periodically, but since it does not occupy all the time axes, the number of relay stations (n) is the same as the number of relay stations after the broadcast of the broadcast information is finished. A fixed-length time slot is defined, and the broadcast information can be broadcast by a corresponding relay station in each time slot. Thus, the mobile terminal can identify whether the received broadcast information is from the base station or from a certain relay station based on the time of the received broadcast information. Became.

  In another preferred embodiment of the present invention, each relay station uses the fixed-length time slot, and specific information that can uniquely identify itself such as a symbol sequence without transferring broadcast information of the base station. May be sent. In this way, the mobile terminal can still determine the source of information based on the time of the received information and can greatly reduce the length of each fixed time slot, thereby conserving system resources. In this embodiment, each relay station can transfer the broadcast information of the base station at any other self-defined time.

  In step C, the base station allocates a channel for the current mobile terminal based on a resource allocation rule, and indicates the allocated channel to the mobile terminal via a corresponding relay station.

  In step D, the base station and the mobile terminal perform data transmission using the allocated channel. Here, in general, the base station and the mobile terminal perform data transmission via a relay station to which the mobile terminal belongs.

  In the data transmission process in step D, after receiving the data packet, the relay station should further determine whether the currently received data packet should be forwarded by itself and should be forwarded by itself If so, the data packet is transferred, otherwise the data packet is discarded without any operation.

  The above-mentioned resource allocation rules in Step C mainly include the following.

  1) Assign the same channel only to mobile terminals that belong to the coverage of different relay stations.

  The cause is as follows.

  The relay station operates in half duplex. That is, it cannot transmit and receive simultaneously with the same time and frequency resources. At this time, if the same channel is assigned to two users belonging to the same relay station coverage, the relay station must receive information from the base station and transmit information to the user. Not. In this case, since the intensity of the radio frequency transmission signal is 100 to 120 dBm higher than the intensity of the reception signal, the reception signal is completely buried in the transmission signal. As a result, the relay station cannot receive correctly.

  2) Assign the same channel only to a maximum of two mobile terminals.

  The cause is as follows.

  If the same channel is assigned to more than two users, for example, three users, the base station may send different signals to two relay stations at the same time in a certain time slot. Under such conditions, this situation cannot be realized.

3) In a system using variable-length time slots, when there are one or more reusable channels, the same channel as the mobile terminal that currently accesses the mobile terminal that satisfies the following equation (1) is selected. Is assigned.

Where min () function represents minimum value operation, abs () function represents absolute value operation,

Represents the SINR in the y-th hop time slot of the mobile terminal currently accessing the network,

Represents SINR in the y-th hop time slot of another mobile terminal of this cell, and the value of y is 1 or 2.

  As can be seen from equation (1), the resource allocation rule 3) is effectively the SINR of the first hop time slot of the mobile terminal currently accessing the network and the second hop time slot of the other mobile terminal in the cell. The condition that the sum of the absolute value of the difference and the absolute value of the SINR difference between the first hop time slot of the other mobile terminal and the second time slot of the mobile terminal currently accessing the network is minimum. Selecting a satisfactory mobile terminal and assigning the same channel as the mobile terminal currently accessing the network. That is, the mobile terminal closest to the SINR of the mobile terminal currently accessing the network is selected, and the same channel as the mobile terminal accessing the network is assigned.

  The cause is as follows.

  If the same channel is allocated to two two-hop users on the assumption that the time slot length can be adjusted and the traffic volume of each time slot is approximately the same, the time slot length after the allocation becomes a user with low throughput (i.e., Time slot length of a relatively long time slot). In addition, since SINR is one of the key parameters that generally affect the throughput, the length of these two time slots can usually be expressed. Therefore, the resource allocation rule selects and reuses the two time slots closest to SINR, thereby reducing the wasted time as much as possible after reuse and improving the channel utilization rate. As can be seen, this rule applies only to systems with variable time slot length.

  As an explanation, in step C above, in order to allocate a channel to the currently accessed mobile terminal, the base station needs to record the channel resource allocation table of this cell. The channel assignment table includes at least the following items, that is, the identifier of the mobile terminal, the identifier of the relay station to which it belongs, the occupied channel resource and whether or not the channel resource can be reused. The item of whether the channel resource can be reused is determined by the allocation rule 2). That is, after assigning the same channel to two mobile terminals, the channel resource is marked as not reusable.

Table 1 shows an example of a channel resource allocation table recorded by the base station in the TDMA system. In Table 1, the item of channel resource is specifically expressed as a time slot occupied by the mobile terminal.

  As can be seen from Table 1 above, a total of five mobile terminals are accessed in the current cell. That is, mobile terminal 1, mobile terminal 2, mobile terminal 3, mobile terminal 4 and mobile terminal 5. Here, the mobile terminal 1 belongs to the coverage of the relay station 1 and occupies the time slot 1 to perform data transmission. The mobile terminal 2 belongs to the coverage of the relay station 2 and occupies the time slot 2 to perform data transmission. The mobile terminal 3 belongs to the coverage of the relay station 3, and uses the time slot 3 to transmit data. The mobile terminal 4 belongs to the coverage of the relay station 4 and occupies the time slot 1 to perform data transmission. The mobile terminal 5 belongs to the coverage of the relay station 1 and occupies the time slot 4 to perform data transmission. Based on the allocation rule 2), since the mobile terminal 1 and the mobile terminal 4 all occupy the time slot 1, they cannot be reused with other mobile terminals, but are occupied by other mobile terminals. Time slots, for example, time slot 2, time slot 3, and time slot 4, can be reused.

  Based on the above rules, after referring to the channel resource allocation table of this cell, the base station assigns a channel to the mobile terminal based on information such as a relay station to which the mobile terminal accessing the network belongs and SINR. Can be assigned. A specific method for a base station to assign a channel to a mobile terminal mainly includes the following steps.

  In step C1, the base station searches and judges the channel resource allocation table of this cell recorded by itself based on the relay station to which the accessing mobile terminal belongs, and belongs to the mobile terminal from among them If channel resources of a relay station different from the relay station to be searched are found and such a channel resource is found, step C2 is executed, and if not found, step C4 is executed.

  This step is substantially performed based on the above allocation rule 1). That is, the same channel is allocated only to mobile terminals belonging to the coverage of different relay stations.

  In step C2, it is determined whether there is a channel resource that can be reused in the channel resource found in step C1, and if there is, step C3 is executed, and if not, step C4 is executed.

  This step is substantially performed based on the above allocation rule 2). That is, the same channel is allocated only to a maximum of two mobile terminals.

  In step C3, one reusable channel is allocated to the mobile terminal, and the channel resource allocation table of this cell is updated.

  In step C4, a channel is allocated to the current mobile terminal, and the channel resource allocation table of this cell is updated. Here, a new orthogonal channel is generally assigned to the current mobile terminal.

  Thus, the base station assigned a channel to the mobile terminal that is currently accessing the network.

  If the current system is a system having a variable time slot length, after determining in step C2 that there is a time slot that can be reused, the base station does not execute C3 but then executes step C5.

  In steps C5 and C6, it is determined whether or not there is one or more reusable channel resources. If there are, re-execute step C7. Allocate to the accessing mobile terminal and update the channel resource allocation table of this cell.

  In step C7, the SINR owned by the reusable channel resource is compared with the SINR corresponding to the currently accessed mobile terminal, and the channel closest to the SINR of the currently accessed mobile terminal is selected. To the current mobile terminal, and the channel resource allocation table of this cell is updated.

  FIG. 8 is a flowchart of a method for allocating a channel to a mobile terminal that is currently accessing the network in the base station with the variable time slot length.

The above steps C5, C6 and C7 are substantially performed based on the allocation rule 3). As can be seen from this, in order to complete the above operation, the channel resource allocation table recorded by the base station needs to further include the SINR of the channel resource occupied by each mobile terminal. This allows the base station to obtain the SINR occupied by each mobile terminal in a timely manner,
The relay station periodically measures SINR from the base station to the relay station, periodically receives SINR from the relay station to each mobile terminal measured by the mobile terminal, and periodically notifies the base station of the SINR What you need and
The base station updates the SINR of the channel occupied by each mobile terminal in the channel resource allocation table based on the SINR of the channel resource occupied by each mobile terminal broadcast by the relay station; In addition.

Table 2 shows an example of a channel resource allocation table recorded by the base station in a TDMA system having a variable time slot length. In Table 2, the item “channel resource” is specifically expressed as a time slot occupied by the mobile terminal. As can be seen from Table 2, the channel resource allocation table recorded by the base station records the channel resources occupied by each mobile terminal and the SINRs of the first hop time slot and the second hop time slot in the channel resource. ing.

  Hereinafter, an example in which a base station allocates a channel to a mobile terminal using the above method in a variable time slot length system will be described.

  Here, it is assumed that the channel resource allocation table of the current cell recorded by the base station is as shown in Table 2 above, and that the mobile terminal 6 within the coverage of the relay station 3 is accessing the network. To do.

  If it does so, in the said step C1, the base station will search the channel resource which the relay station which is not the relay station 3 has in Table 2, and will obtain the time slot 1, the time slot 2, and the time slot 4.

  Next, in step C2, the base station checks whether time slot 1, time slot 2 and time slot 4 can be reused. As a result, time slot 1 cannot be reused, but time slot 2 and time slot 4 can be reused.

  Next, in steps C5 to C7, the base station compares the SINR of the currently accessed mobile terminal with the SINR of the first hop and the second hop of the time hop that can be reused. Since the SINR of the currently accessed mobile terminal is 10.5 and 8, the SINA of timeslot 2 is closest to the mobile terminal 6 by calculation based on Equation 1 of the allocation rule 3) Time slot 2 is selected as the channel resource of the current mobile terminal.

Finally, the channel resource allocation table of this cell is updated based on the channel resource allocation result. At this time, based on the allocation rule 2), since the time slot 2 cannot be reused, all items regarding whether or not the time slot 2 can be reused are changed to “NO”. The updated channel resource allocation table is as shown in Table 3.

  As can be seen from this, after the channel assignment operation, the base station assigns, for example, time slot 2 to the mobile terminal currently accessing the network.

In particular, the time slot allocated for each two-hop user by the channel resource allocation method is actually the long time slot described above, and the long time slot further includes two short time slots, Among them, one short time slot is used for data transmission from the base station to the relay station, that is, the first hop time slot, and another short time slot is used for data transmission from the relay station to the base station, That is, the second hop time slot. Therefore, when allocating the same channel to two such users, the first hop time slot of the first user and the second hop time slot of the first user are ensured to ensure that the base station communicates with only one mobile terminal at the same time. The second user's second hop time slot is reused as the first time slot of the long time slot, the second user's first hop time slot and the first user's second hop time slot. Can be used in the second short time slot of the long time slot. This realizes that two users use the same time slot.

  Hereinafter, the resource allocation method of the present invention will be described in detail by taking as an example a TDMA system in which each cell shown in FIG. 1 includes four relay stations.

  In the following embodiments, two different TDMA frame configurations, ie, a fixed time slot length TDMA frame configuration and a variable time slot length TDMA frame configuration are reused by the resource allocation method of the present invention. The TDMA frame configuration used in FIG. Similarly, assume that mobile terminals are uniformly distributed within the cell.

Example 1
In the first embodiment, resource allocation is performed for the frame configuration shown in FIG. If the resource allocation method of the present invention is adopted for the frame configuration shown in FIG. 2, the frame configuration shown in FIG. 9 can be obtained. Such a frame configuration is applied to any network situation. As can be seen from FIG. 9, the frame configuration includes a total of five short time slots. Among them, in the first short time slot, the base station performs data transmission with the first relay station FRS1, and the second relay station FRS2 performs data transmission with the mobile terminal covered thereby. In the second time slot, the base station performs data interchange with the second relay station FRS2 and the first relay station FRS1 performs data interchange with the mobile terminal covered thereby. In the third short time slot, the base station performs data interchange with the third relay station FRS3, and the fourth relay station FRS4 performs data interchange with the mobile terminal covered thereby. Within the fourth short time slot, the base station performs data interchange with the fourth relay station FRS4, and the third relay station FRS3 performs data interchange with the mobile terminal covered thereby. Within the fifth short time slot, the base station alternates data with the mobile terminal covered by it, ie, a one-hop user.

As can be seen from the frame configuration shown in FIG. 9, in the first embodiment, there is substantially one mobile terminal covered by the first relay station FRS1 and one mobile terminal covered by the second relay station FRS2. , Assign the same time slot (first and second short time slot), the same for one mobile terminal covered by the third relay station FRS3 and one mobile terminal covered by the fourth relay station FRS4 Allocate time slots (third and fourth short time slots). This resource allocation method shortens the length of the TDMA frame structure from the nine short time slots shown in FIG. 2 to the five short time slots shown in FIG. Has been increased. Throughput obtained by employing the resource allocation method in the first embodiment can be calculated by the formula (2).

Here, TP _AP-FRS represents the throughput between the base station and the relay station, TP _FRS-MT represents the throughput between the relay station and the mobile terminal, and TP _AP-MT represents the throughput between the base station and the mobile terminal. The function min () represents the minimum value calculation.

(Example 2)
In the second embodiment, resource allocation is performed for the frame configuration shown in FIG. This embodiment is based on the following assumptions. That is, in an urban environment, two adjacent relay stations are separated from each other by a building, so that transmission from the relay station to the mobile terminal can be performed simultaneously.

  The frame configuration shown in FIG. 10 can be obtained by employing the resource allocation method of the present invention for the frame configuration shown in FIG. As can be seen from FIG. 10, the frame configuration includes a total of five short time slots. Among them, the base station performs data transmission with the first relay station FRS1 within the first short time slot. In the second time slot, the first relay station FRS1 performs data alternation with the mobile terminal covered thereby, and the second relay station FRS2 performs data alternation with the mobile terminal covered thereby. Also performs data interchange with the third relay station FRS3. In the third short time slot, the base station performs data interchange with the fourth relay station FRS4. Within the fourth short time slot, the base station performs data interchange with the second relay station FRS2, the fourth relay station FRS4 performs data interchange with the mobile terminal covered thereby, and the third relay Station FRS3 performs data interchange with the mobile terminal covered thereby. Within the fifth short time slot, the base station alternates data with the mobile terminal covered by it, ie, a one-hop user.

  As can be seen from the frame configuration shown in FIG. 10, in the second embodiment, the mobile terminal substantially covered by the third relay station FRS3 and the mobile terminal covered by the second relay station FRS2, Because the same time slot (second and fourth short time slots) is allocated and there is a building between adjacent relay stations, the first relay station FRS1 and the second relay station FRS2 are simultaneously covered by it Data exchange can be performed with the terminal, and the third relay station FRS3 and the fourth relay station FRS4 can simultaneously perform data exchange with the mobile terminal covered thereby. This resource allocation method reduces the length of the TDMA frame structure from the seven short time slots shown in FIG. 3 to the five short time slots shown in FIG. 10, thus increasing the system throughput and channel utilization. Has been. Throughput obtained by adopting the resource allocation method in the second embodiment can also be calculated by the formula (2).

(Example 3)
In the third embodiment, resource allocation is performed for the frame configuration shown in FIG. This embodiment uses a smart antenna at the base station and is based on the following assumptions. That is, in an urban environment, two adjacent relay stations are separated from each other by a building, so that transmission from the relay station to the mobile terminal can be performed simultaneously.

  By adopting the resource allocation method of the present invention for the frame configuration shown in FIG. 4, the frame configuration shown in FIG. 11 can be obtained. As can be seen from FIG. 11, the frame structure includes three short time slots. Among them, in the first short time slot, the base station exchanges data with all the relay stations via the smart antenna. Within the second short time slot, the first relay station FRS1 performs data alternation with the mobile terminal covered thereby, and the second relay station FRS2 performs data alternation with the mobile terminal covered thereby. . Within the third short time slot, the third relay station FRS3 performs data alternation with the mobile terminal covered thereby, and the fourth relay station FRS4 performs data alternation with the mobile terminal covered thereby. The base station performs data interchange with the mobile terminal directly covered by it, i.e. one-hop user.

As can be seen from the frame configuration shown in FIG. 11, depending on such a resource allocation method, the length of the TDMA frame configuration is increased from the two short time slots shown in FIG. 4 to the three short time slots shown in FIG. However, since only one frequency band is used in the above method of the present embodiment, two frequency bands are saved. Therefore, the system throughput and the channel utilization rate are relatively improved compared to the situation shown in FIG. Throughput obtained by employing the resource allocation method in the fourth embodiment can be calculated by the formula (3).

  Here, the meaning of each parameter is the same as formula (2).

  FIG. 12 is a relationship diagram between the throughput and the distance from the base station to the mobile terminal in the first, second, and third embodiments of the present invention and the conventional first, second, and third channel allocation methods. Here, the lowermost solid curve in FIG. 12, the curve including the regular triangle and the inverted triangle is the relationship between the throughput obtained by the conventional first, second, and third channel allocation methods and the distance from the base station to the mobile terminal, respectively. Is shown. Curves including diamonds indicate the relationship between the throughput obtained by the first and second embodiments of the present invention and the distance from the base station to the mobile terminal. A curve including a cross indicates the relationship between the throughput obtained by the third embodiment of the present invention and the distance from the base station to the mobile terminal. As can be seen from FIG. 12, Embodiments 1, 2, and 3 of the present invention can be brought about by space independence, with relatively large improvements over the conventional first, second, and third channel allocation methods, respectively. Space diversity gain can be used effectively, which greatly improves system throughput.

(Example 4)
In the fourth embodiment, resource allocation is performed for the frame configuration shown in FIG. By adopting the resource allocation method of the present invention for the frame configuration shown in FIG. 5, the frame configuration shown in FIG. 13 can be obtained. The frame configuration can be applied to any network architecture. As can be seen from FIG. 13, the frame configuration includes a total of five variable length short time slots. Among these, in the first short time slot, the base station performs data transmission with the first relay station FRS1, and the second relay station FRS2 performs data interchange with the mobile terminal covered thereby. Within the second short time slot, the base station performs data interchange with the second relay station FRS2 and the first relay station FRS1 performs data interchange with the mobile terminal covered thereby. In the third short time slot, the base station performs data interchange with the third relay station FRS3, and the fourth relay station FRS4 performs data interchange with the mobile terminal covered thereby. Within the fourth short time slot, the base station performs data interchange with the fourth relay station FRS4, and the third relay station FRS3 performs data interchange with the mobile terminal covered thereby. Within the fifth short time slot, the base station alternates data with the mobile terminal covered by it, ie, a one-hop user. Since the time required for data alternating between the relay station and the mobile terminal must be longer than the time required for data alternating between the base station and the relay station under the condition that the throughput is the same, the previous four The length of the short time slot should be determined by the time required for data exchange between the relay station and the mobile terminal.

As can be seen from the frame configuration shown in FIG. 13, in the fourth embodiment, in practice, one mobile terminal covered by the first relay station FRS1 and one mobile terminal covered by the second relay station FRS2 , Assign the same time slot (first and second short time slot), one mobile terminal covered by the third relay station FRS3 and one mobile terminal covered by the fourth relay station FRS4 are the same Assigned time slots (third and fourth short time slots). This resource allocation method shortens the length of the TDMA frame structure from the nine short time slots shown in FIG. 5 to the five short time slots shown in FIG. 13, thus increasing system throughput and channel utilization. Has been. Throughput obtained by employing the resource allocation method in the fourth embodiment can be calculated by the formula (4).

Here, Packet represents the capacity of the message transmitted in each short time slot, function max () represents the maximum value calculation, TP _MP-MT represents the throughput from the base station to the mobile terminal or the relay station to the mobile terminal Where MP is a media point, which is a generic term for a base station and a relay station, and the meanings of the other parameters are the same as those of the formula (2).

(Example 5)
In the fifth embodiment, resource allocation is performed for the frame configuration shown in FIG. This embodiment is based on the following assumptions. That is, in an urban environment, two adjacent relay stations are separated from each other by a building, so that transmission from the relay station to the mobile terminal can be performed simultaneously.

  The frame configuration shown in FIG. 14 can be obtained by adopting the resource allocation method of the present invention for the frame configuration shown in FIG. As can be seen from FIG. 14, the frame structure includes three short time slots. Among them, in the first short time slot, the base station sequentially performs data interchange with the third relay station FRS3 and the fourth relay station FRS4, and the first relay station FRS1 alternates data with the mobile terminal covered thereby. The second relay station FRS2 also performs data interchange with the mobile terminal covered by the second relay station FRS2. Within the second short time slot, the base station in turn alternates data with the first relay station FRS1 and the second relay station FRS2, and the third relay station FRS3 alternates data with the mobile terminal covered thereby. The fourth relay station FRS4 also performs data interchange with the mobile terminal covered by it. Within the third short time slot, the base station alternates data with the mobile terminal covered by it, ie one-hop user.

As can be seen from the frame configuration shown in FIG. 14, since there is a building between adjacent relay stations, the first relay station FRS1 and the second relay station FRS2 perform data alternating with the mobile terminals covered by them simultaneously. The third relay station FRS3 and the fourth relay station FRS4 can simultaneously perform data interchange with the mobile terminals covered thereby. Therefore, in the fourth embodiment, one mobile terminal covered by the first relay station FRS1 and one mobile terminal covered by the second relay station FRS2 are substantially covered by one relay terminal FRS3. The same time slot (first and second short time slots) is allocated to one mobile terminal covered by the mobile terminal and the fourth relay station FRS4. This resource allocation method shortens the length of the TDMA frame structure from the seven short time slots shown in FIG. 3 to the three short time slots shown in FIG. 14, thus increasing the system throughput and channel utilization. Is done. Throughput obtained by adopting the resource allocation method in the fifth embodiment can be calculated by the formula (5).

  Here, the meaning of each parameter is the same as formula (4).

(Example 6)
In the sixth embodiment, resource allocation is performed for the frame configuration shown in FIG. This embodiment uses a smart antenna at the base station and is based on the following assumptions. That is, in an urban environment, two adjacent relay stations are separated from each other by a building, so that transmission from the relay station to the mobile terminal can be performed simultaneously.

  By adopting the resource allocation method of the present invention for the frame configuration shown in FIG. 4, the frame configuration shown in FIG. 15 can be obtained. As can be seen from FIG. 15, the frame structure includes three short time slots. Among them, in the first short time slot, the base station performs data interchange with all the relay stations by the smart antenna. Within the second short time slot, the first relay station FRS1 performs data alternation with the mobile terminal covered thereby, and the second relay station FRS2 performs data alternation with the mobile terminal covered thereby. . Within the third short time slot, the third relay station FRS3 performs data alternation with the mobile terminal covered thereby, and the fourth relay station FRS4 performs data alternation with the mobile terminal covered thereby. The base station performs data interchange with the mobile terminal directly covered by it, i.e. one-hop user.

As can be seen from the frame configuration shown in FIG. 15, depending on the resource allocation method, the length of the TDMA frame configuration is increased from the two short time slots shown in FIG. 4 to the three short time slots shown in FIG. However, since only one frequency band is used in the above method of the present embodiment, two frequency bands are saved. Therefore, the system throughput and the channel utilization rate are relatively improved compared to the situation shown in FIG. The throughput obtained by adopting the resource allocation method in the fourth embodiment can be calculated by the formula (6).

Here, the meaning of each parameter is the same as formula (4). FIG. 16 shows throughput, movement from the base station in the fourth, fifth, and sixth channel allocation methods according to the fourth, fifth, and sixth embodiments of the present invention. The relationship with the distance to the terminal is shown. Here, the lowermost solid curve, the dotted curve and the curve including the equilateral triangle in FIG. 16 are the relationship between the throughput obtained by the conventional fourth, fifth and sixth channel allocation methods and the distance from the base station to the mobile terminal, respectively. Is shown. A curve including a rhombus indicates a relationship between the throughput obtained by the fourth embodiment of the present invention and the distance from the base station to the mobile terminal. A curve including a hexagonal star indicates a relationship between the throughput obtained by the fifth embodiment of the present invention and the distance from the base station to the mobile terminal. A curve including an inverted triangle indicates the relationship between the throughput obtained by Embodiment 6 of the present invention and the distance from the base station to the mobile terminal. As can be seen from FIG. 16, Embodiments 4, 5, and 6 of the present invention can be brought about by space independence, with relatively large improvements over the conventional fourth, fifth, and sixth channel allocation methods, respectively. Space diversity gain can be used effectively, which greatly improves system throughput.

  As described above, the preferred embodiment has been described by taking a TDMA system as an example, but the resource allocation method of the present invention is not only applied to TDMA but also applied to other relay-based cellular mobile communication systems. Can be done.

  The relay stations used in the conventional relay-based mobile communication system are all analog, and the relay is realized by adopting the direct transfer method for the information from the base station and the mobile terminal. In the relay-based mobile communication system, the resource allocation method of the present invention cannot be realized.

  Therefore, the present invention also provides a mobile communication system capable of realizing the resource allocation method of the present invention and a relay station used in the communication system.

  Each cell of the relay-based mobile communication system of the present invention mainly includes one base station, one or more relay stations, and mobile terminals. Here, the hardware configurations of the base station and the mobile terminal are almost the same as the hardware configurations of the conventional base station and the mobile terminal, respectively, but the base station is occupied by the relay station to which each mobile terminal in the cell belongs. It is necessary to record a channel resource allocation table for recording information such as channels. The base station performs channel resource selection for the mobile terminal accessing the network based on the channel resource allocation table.

The relay station used in the cellular mobile communication system is greatly different from the relay station used in the prior art. Its internal configuration is mainly as shown in FIG.
An antenna that receives a reception signal from a base station or a mobile terminal when the relay station receives the signal, and transmits a signal waiting for transmission to the base station or the mobile terminal when the relay station transmits;
A receiving element that performs operations such as down-converter, demodulation and decoding on the received signal, and determines whether to transfer the processed data;
A transmitting element that performs encoding, modulation, and up-converter processing on the data that needs to be transferred, processed by the receiving element, and generates a signal waiting for transmission;
A signal waiting for transmission generated by the transmitting element is output to the antenna when the relay station transmits, and a signal received by the antenna is connected to the receiving element when the relay station receives the signal. And a transmission / reception conversion switch that realizes conversion between the transmission and reception functions of the relay station.

  Here, the receiving element includes a down-converter module that performs a down-converter process on a received signal, a demodulating module that demodulates a signal output after being down-converted by the down-converter module, and a demodulating module A decoding module that decodes the signal that is output after being demodulated by the decoder, and the data that is output after being decoded by the decoding module and needs to be identified and transferred And an identification module for determining whether or not there is.

  The transmission element includes an encoding module that performs encoding on data that needs to be transferred, a modulation module that modulates data output after being encoded by the encoding module, and a modulation module. And an up-converter module that performs up-converter processing on the signal output after being modulated.

As can be seen, the resource allocation method of the present invention can be realized by the relay station based mobile communication system. This allows resource allocation to take advantage of the inherent property of having independent spatial links in a relay station based cellular network, increasing system throughput and channel utilization.

It is a figure which shows the conventional relay-based cellular structure. It is a TDMA frame block diagram using the conventional 1st channel allocation method. It is a TDMA frame block diagram using the conventional 2nd channel allocation method. It is a TDMA frame block diagram using the conventional 3rd channel allocation method. FIG. 6 is a TDMA frame configuration diagram using a conventional fourth channel allocation method. FIG. 9 is a TDMA frame configuration diagram using a conventional fifth channel allocation method. 4 is a flowchart of a method for performing resource allocation in a relay-based cell according to the present invention. 3 is a flowchart of a method for allocating a channel to a mobile terminal in which a base station is currently accessing a network in a variable time slot length TDMA system according to the present invention; It is the frame block diagram after performing the resource allocation by Example 1 of this invention. FIG. 10 is a frame configuration diagram after resource allocation according to Embodiment 2 of the present invention. FIG. 10 is a frame configuration diagram after resource allocation according to Embodiment 3 of the present invention. FIG. 6 is a diagram showing the relationship between the throughput and the distance from the base station to the mobile terminal when using the first, second, and third embodiments of the present invention and the conventional first, second, and third channel allocation methods. FIG. 10 is a frame configuration diagram after performing resource allocation according to Embodiment 4 of the present invention. FIG. 10 is a frame configuration diagram after performing resource allocation according to Embodiment 5 of the present invention. FIG. 10 is a frame configuration diagram after performing resource allocation according to Embodiment 6 of the present invention. FIG. 10 is a diagram showing the relationship between the throughput and the distance from the base station to the mobile terminal when using the fourth, fifth and sixth embodiments of the present invention and the conventional fourth, fifth and sixth channel allocation methods. It is an internal block diagram of the relay station by this invention.

Explanation of symbols

AP ... base station, MT ... mobile terminal, FRS ... relay station,

Claims (20)

A resource allocation method in a relay-based cellular configuration, comprising:
A mobile terminal accessing the network monitors broadcast information from the base station and all relay stations in the network to determine whether it is a one-hop user or a two-hop user, and If it is determined that it is a hop user, it determines which relay station it belongs to based on the received broadcast information, and relay station information to which it belongs to the base station via the relay station. Feedback step a,
The base station assigns a channel to the current mobile terminal based on resource allocation rules, and instructs the mobile terminal to the assigned channel via a relay station to which the mobile terminal belongs;
The method comprising the step c wherein the base station and the mobile terminal perform data transmission using the assigned channel. Monitoring broadcast information from the base station and all relay stations in the network in step a,
Step a1 in which the base station periodically broadcasts broadcast information through a broadcast channel;
After the relay station in the coverage of the base station receives the broadcast information broadcasted by the base station, step a2 for forwarding the broadcast information from the base station to the mobile terminal in the coverage;
2. The resource allocation method according to claim 1, comprising a step a3 in which a mobile terminal accessing the network receives broadcast information transmitted by a base station and broadcast information transferred by a relay station. Whether the mobile terminal is a one-hop user by measuring the signal-to-interference power and noise ratio or received power of broadcast information from the received base station and all relay stations in the network in step a Or if you ’re a two-hop user,
Specifically, the determination in step a is as follows:
Step a4 in which the mobile terminal measures the signal-to-interference power and noise ratio of the broadcast information from the received base station and all relay stations in the network;
Search for broadcast information having the maximum signal-to-interference power and noise ratio from among them, and if the broadcast information is from a base station, the mobile terminal determines that it is a one-hop user, 2. The resource allocation method according to claim 1, further comprising step a5 of determining that the mobile terminal is a two-hop user if the broadcast information is from a relay station.   In step a, the mobile terminal that determines to which relay station the mobile terminal belongs belongs to the broadcast station based on the relay station characteristic information attached to the broadcast information having the maximum signal-to-interference power and noise ratio. 2. The resource allocation method according to claim 1, wherein the relay station that has transferred the information is identified and it is determined that the relay station belongs to the coverage of the relay station.   5. The resource allocation method according to claim 4, wherein the feature information is information on different times and / or code channels and / or channels used when each relay station broadcasts.   2. The resource allocation method according to claim 1, wherein the resource allocation rule in step b includes allocating the same channel only to mobile terminals belonging to the coverage of different relay stations. Assigning a channel to the current mobile terminal in step b
When the base station searches for and finds a channel resource of a relay station different from the relay station to which the mobile terminal belongs in the channel resource allocation table of the cell based on the relay station to which the mobile terminal belongs, If b12 is executed and not found, step b11 is executed to execute step b13;
It is determined whether there is a channel resource that can be reused in the found channel resource. If there is one, a channel that can be reused is allocated to the mobile terminal, and the channel resource allocation table of this cell is updated. If not, step b12 for executing step b13;
7. The resource allocation method according to claim 6, comprising a step b13 of allocating a channel to a current mobile terminal and updating a channel resource allocation table of the cell.   The resource allocation rule further includes allocating a channel closest to a signal-to-interference power and a noise ratio of a currently accessed mobile terminal when there is one or more reusable channel resources. 7. The resource allocation method according to claim 6. The method
The relay station periodically measures the signal-to-interference power and noise ratio from the base station to the relay station, and periodically measures the signal-to-interference power and noise ratio from the relay station to each mobile terminal measured by the mobile terminal. Receiving and reporting to the base station,
Based on the signal-to-interference power and noise ratio reported by the relay station, the base station updates the channel resource information occupied by each mobile terminal in the intra-cell channel resource allocation table recorded by itself. And further including
In step b, allocating a channel to the current mobile terminal
Based on the relay station to which the accessed mobile terminal belongs, the channel resource allocation table is searched for a channel resource possessed by a relay station different from the relay station to which the mobile terminal belongs, and such a channel resource is obtained. If found, execute step b22; if not found, execute step b24;
It is determined whether there is a channel resource that can be reused in the found channel resource, and if there is, step b23 is executed; otherwise, step b22 is executed;
It is determined whether there are one or more reusable channel resources, and if there are, the signal-to-interference power and noise ratio of the reusable channel resources and the signal pair corresponding to the currently accessed mobile terminal, respectively. Compare the interference power and noise ratio, assign the channel closest to the signal-to-interference power and noise ratio of the currently accessed mobile terminal to the current mobile terminal, and set the channel resource allocation table for this cell. If not updated, step b23 for allocating the reusable channel to the currently accessing mobile terminal and updating the channel resource allocation table of this cell;
Assigning a channel to the current mobile terminal and updating the channel resource assignment table of this cell b24,
9. The resource allocation method according to claim 8, wherein Specifically, allocating a channel closest to the signal-to-interference power and noise ratio of the currently accessed mobile terminal to the current mobile terminal,
Assigning a channel occupied by a mobile terminal satisfying to the currently accessed mobile terminal,
Where min () function represents minimum value operation, abs () function represents absolute value operation,
Represents the signal-to-interference power and noise ratio in the y-th hop time slot of the mobile terminal currently accessing the network,
Represents the signal-to-interference power and noise ratio in the y-th hop time slot of another mobile terminal of this cell, and the value of y is 1 or 2. Resource allocation method. In a time division multiple access system, the channel resource is a time slot;
In step c, the base station and the mobile terminal perform data transmission using an allocated channel,
Two short time slot resources are allocated to two two-hop mobile terminals, and the first short time slot is simultaneously assigned to the first hop time slot and the second mobile of the first mobile terminal in the two mobile terminals. The second hop time slot of the terminal, and the second short time slot simultaneously as the second hop time slot of the first mobile terminal and the first hop time slot of the second mobile terminal. Including,
2. The resource allocation method according to claim 1, wherein   12. The resource allocation method according to claim 11, wherein the short time slot resource is a basic time slot resource in a time division multiple access system.   12. The resource allocation method according to claim 11, wherein the short time slot resource is a short time slot obtained by dividing a basic time slot in a time division multiple access system into two time slots.   In the process of data transmission in step c, after receiving the data packet, the relay station should determine whether the currently received data packet should be forwarded by itself and should be forwarded by itself. 2. The resource allocation method according to claim 1, wherein the data packet is transferred, and if not, the data packet is discarded. Each cell is a relay-based mobile communication system including one base station, one or more relay stations, and a mobile terminal,
The base station records a channel resource allocation table of the cell, allocates a channel to a mobile terminal accessing the cell based on the channel resource allocation table,
The relay station is
An antenna that receives a reception signal from a base station or a mobile terminal when the relay station receives the signal, and transmits a signal waiting for transmission to the base station or the mobile terminal when the relay station transmits;
A receiving element that performs operations such as down-converter, demodulation and decoding on the received signal, and determines whether to transfer the processed data;
A transmitting element that performs encoding, modulation, and up-converter processing on the data that needs to be transferred, processed by the receiving element, and generates a signal waiting for transmission;
A signal waiting for transmission generated by the transmitting element is output to the antenna when the relay station transmits, and a signal received by the antenna is connected to the receiving element when the relay station receives the signal. A transmission / reception conversion switch that realizes conversion between the transmission and reception functions of the relay station,
This system characterized by that. The receiving element in the relay station,
A down-converter module that performs down-converter processing on the received signal;
A demodulation module that demodulates the signal after being downconverted by the downconverter module;
A decoding module for decoding the signal demodulated by the demodulation module;
16. The relay according to claim 15, further comprising an identification module that performs identification on data obtained after being decrypted by the decryption module and determines whether transfer is necessary. Based mobile communication system. The transmitting element in the relay station,
An encoding module for encoding data that needs to be transferred from the receiving element;
A modulation module that modulates the data after being encoded by the encoding module;
16. The relay-based mobile communication system according to claim 15, further comprising an up-converter module that performs up-converter processing on a signal after being modulated by the modulation module. A relay station,
An antenna that receives a reception signal from a base station or a mobile terminal when the relay station receives the signal, and transmits a signal waiting for transmission to the base station or the mobile terminal when the relay station transmits;
A receiving element that performs operations such as down-converter, demodulation and decoding on the received signal, and determines whether to transfer the processed data;
A transmitting element that performs encoding, modulation, and up-converter processing on the data that needs to be transferred, processed by the receiving element, and generates a signal waiting for transmission;
A signal waiting for transmission generated by the transmitting element is output to the antenna when the relay station transmits, and a signal received by the antenna is connected to the receiving element when the relay station receives the signal. The relay station further comprises a transmission / reception conversion switch for realizing conversion between transmission and reception functions of the relay station. The receiving element is
A down-converter module that performs down-converter processing on the received signal;
A demodulation module that demodulates the signal after being downconverted by the downconverter module;
A decoding module for decoding the signal demodulated by the demodulation module;
19. The relay according to claim 18, further comprising: an identification module that performs identification on data obtained after being decrypted by the decryption module and determines whether transfer is necessary. Bureau. The transmitting element is
An encoding module for encoding data that needs to be transferred from the receiving element;
A modulation module that modulates the data after being encoded by the encoding module;
19. The relay station according to claim 18, further comprising an up-converter module that performs an up-converter process on the signal modulated by the modulation module.