CN101800569A - Method for transmitting reference marks and base station - Google Patents

Abstract

The present invention discloses a reference symbol sending method and a base station. The method includes: the base station assigns reference symbol time-frequency resources to each relay station located in the same cell as the base station in the downlink control domain and notifies the relay station that each relay station assigns it The reference symbols are sent on the time-frequency resources of the reference symbols. The base station includes a reference symbol time-frequency resource allocation module and a resource notification module. Using the method and base station of the present invention can reduce the impact on the backward compatibility of the terminal, and by allocating different reference symbol time-frequency resources for the base station and each relay station, it can prevent the reference symbol of the base station and the relay station when the downlink works simultaneously. The collision of the symbol and the reference symbol of each relay station.

Description

Method for sending reference symbols and base station

technical field

The invention relates to the field of wireless communication, in particular to a method for sending reference symbols in a mobile communication system including a relay station and a base station.

Background technique

The development requirements of the next generation mobile communication system (B3G/4G) in mobile communication are to support higher transmission rate, better signal coverage and higher resource utilization. In order to achieve a high transmission rate, the next generation mobile communication system will use a higher frequency band to transmit signals, and a higher frequency bandwidth will bring greater path loss at the same time, affecting network coverage. Relay (Relay) technology can increase coverage and balance, increase cell throughput, and the relay station (Relay Station referred to as RS) has a relatively small configuration cost compared to the base station (BaseStation referred to as BS), so the relay is regarded as a lower A key technology in a generation of mobile communication systems.

As shown in Figure 1, in a mobile communication system including a relay station, there are two ways for a user terminal (UserEquipment, UE) to communicate with a base station: one is to use a traditional communication network to directly communicate with a base station, and the other is to use a traditional communication network to directly communicate with a base station. The first is to communicate with the base station through the relay service of the relay station. In the relay communication method, the overhead of time-frequency resources will increase significantly compared with the first direct communication method. In OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) communication systems, especially after the introduction of relay stations, the effective management of time-frequency resources has a very important impact on improving the system's spectrum efficiency and increasing system capacity.

In a wireless communication system including a relay station, the signal of the base station needs to reach and pass through the relay station. If the base station and the relay station work on the downlink at the same time and when the base station and each relay station have overlapping coverage areas, the reference symbol (Reference Symbol) sent by the relay station may cause interference to terminals that do not support relay technology, and the base station and each relay station may also be in the Sending reference symbols on the same time-frequency resource will cause the reference symbols of the base station and each relay station to collide, which will bring problems such as difficulty in routing selection, inaccurate channel measurement, and reduced resource utilization to the base station, relay station, and terminal.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for sending reference symbols in a communication system including a relay station and a base station, so as to reduce the impact on backward compatibility of terminals.

In order to solve the above problems, the present invention provides a method for sending reference symbols, a method for sending reference symbols, including: the base station allocates reference symbol time-frequency resources for each relay station in the same cell as the base station in the downlink control domain and notifies the Relay stations, each relay station sends reference symbols on the reference symbol time-frequency resource allocated to it.

Further, the resource element positions occupied by the time-frequency resources of the respective relay station reference symbols in the downlink control domain are different from each other.

Further, when the relay station transmits reference symbols at multiple antenna ports, the base station allocates reference symbol time-frequency resources for each antenna port that transmits reference symbols in each relay station, and at the antenna port that transmits reference symbols, the relay station The reference symbols are transmitted on the reference symbol time-frequency resources allocated for the antenna port, and the resource element positions occupied by the reference symbol time-frequency resources corresponding to the antenna ports in the downlink control domain are different from each other.

Further, the base station allocates reference symbol time-frequency resources to each relay station in the same cell as the base station and the base station in the downlink control domain, and notifies the relay station of the reference symbol time-frequency resources allocated to the relay station, the The base station and each relay station respectively send reference symbols on the reference symbol time-frequency resources allocated thereto.

Further, when allocating reference symbol time-frequency resources for the base station and each relay station in the same cell, the resource element positions occupied by the base station, each relay station, and the reference symbol time-frequency resources between different relay stations in the downlink control domain are different from each other.

Further, when the base station and/or relay station transmits reference symbols on multiple antenna ports, the base station allocates reference symbol time-frequency resources to each antenna port of the base station and/or each relay station that transmits reference symbols, and the base station and /or each relay station uses the reference symbol time-frequency resource allocated to the antenna port to send the reference symbol at the antenna port that transmits the reference symbol respectively, and the reference symbol time-frequency resource corresponding to each antenna port occupies resources in the downlink control domain Element positions are different from each other.

Further, the reference symbol time-frequency resource does not include the time-frequency resource for the base station to send common pilots in the downlink control domain; in the long-term evolution system and the advanced long-term evolution system, the reference symbol time-frequency resource in the downlink control domain is used to control Allocation is done in units of channel elements.

Further, the base station and/or the relay station also notifies the terminal of the allocation of the reference symbol time-frequency resource.

In order to solve the above problems, the present invention provides a base station, which includes a reference symbol time-frequency resource allocation module and a resource notification module; the reference symbol time-frequency resource allocation module is used to ensure that the base station is in the same cell as the base station Under the condition that the respective reference symbol time-frequency resources of each relay station occupy different resource element positions in the downlink control domain, assign reference symbol time-frequency resources to each relay station; and notify the resource allocation module to the resource notification module; The resource notification module is configured to notify each relay station and/or terminal of the reference symbol time-frequency resource allocated to each relay station.

Further, the base station also includes a reference symbol sending module; the reference symbol time-frequency resource allocation module is also used to ensure that the base station and each relay station in the same cell as well as the respective reference symbol time-frequency resources between each relay station Under the condition that resource elements occupied by resources in the downlink control domain are different from each other, allocate reference symbol time-frequency resources to the base station and each relay station; and send resource information allocated to the base station to the reference symbol sending module; The reference symbol sending module is further configured to send reference symbols on the reference symbol time-frequency resources allocated for the base station by the reference symbol time-frequency resource allocation module.

Adopting the method and the base station of the present invention can reduce the impact on the backward compatibility of the terminal, and by allocating different reference symbol time-frequency resources for the base station and each relay station, it can prevent the base station and the relay station from working on the downlink at the same time. Collisions of reference symbols between relay stations and between different relay stations.

Description of drawings

FIG. 1 is a schematic diagram of a connection mode between a user terminal and a base station and a relay station in a mobile communication system including a relay station;

Fig. 2 is the flow chart of reference symbol transmission method among the present invention;

Fig. 3 is a long-term evolution (Long Term Evolution, referred to as LTE) system in a downlink subframe with a common cyclic prefix length and a structural schematic diagram of a physical resource block in the subframe;

Fig. 4 is a schematic diagram of a mapping pattern of reference symbols of a base station and each relay station in the physical resource block described in Fig. 3 in a specific embodiment.

Detailed ways

In the present invention, the base station allocates reference symbol time-frequency resources for the base station and each relay station in the same cell as the base station in the downlink control domain, avoiding the interference of the reference symbols sent by the relay station on the data reception of terminals that do not support relay technology, and reducing the impact on the terminal impact on backward compatibility.

When ensuring that the common pilot transmitted by the base station in the downlink control domain is not interfered by the signal sent by the relay station, the base station can only allocate reference symbol time-frequency resources to each relay station in the same cell as the base station in the downlink control domain, which can also reduce the impact on the terminal. impact on compatibility.

When the base station only allocates reference symbol time-frequency resources to each relay station in the same cell, in order to prevent the conflict of the reference symbols of each relay station when the relay stations work on the downlink at the same time, the respective reference symbol time-frequency resources of each relay station are in the downlink control domain The positions of the resource elements occupied in are different from each other. When the base station allocates reference symbol time-frequency resources for the base station and each relay station in the same cell, in order to prevent the base station and each relay station from working on the downlink at the same time. The resource element positions occupied by the reference symbol time-frequency resources in the downlink control domain are different among different relay stations.

The base station in this embodiment includes a reference symbol time-frequency resource allocation module and a resource notification module;

A reference symbol time-frequency resource allocation module, configured to allocate to each relay station under the condition that resource element positions occupied by respective reference symbol time-frequency resources of each relay station in the same cell as the base station are different in the downlink control domain. Reference symbol time-frequency resources; and notify the resource allocation to the resource notification module;

The resource notification module is configured to notify each relay station and/or terminal of the reference symbol time-frequency resource allocated to each relay station.

The reference symbol time-frequency resource allocation module is also used to ensure that the resource element positions occupied by the base station and each relay station in the same cell as well as the respective reference symbol time-frequency resources between each relay station in the downlink control domain are different from each other Under the conditions, allocate reference symbol time-frequency resources to the base station and each relay station; and send the resource information allocated to the base station to the reference symbol sending module;

The reference symbol sending module is further configured to send reference symbols on the reference symbol time-frequency resources allocated for the base station by the reference symbol time-frequency resource allocation module.

The resource element positions occupied by the base station, the relay station, and the reference symbol time-frequency resources in the downlink control domain between each relay station are different from each other.

As shown in Figure 2, the method for sending reference symbols includes the following steps:

Step 201, the base station allocates part of the time-frequency resources in the downlink control domain to the base station and each relay station in the same cell, respectively, as the reference symbol time-frequency resources of the base station and each relay station;

The downlink control domain refers to the first n OFDM symbols in each subframe in LTE and LTE-A (LTE-Advanced, Advanced LTE) systems, n is an integer greater than zero, and in the LTE system, n is greater than zero and less than An integer equal to 4 refers to physical resources used to send information such as terminal scheduling and configuration in other systems. Wherein, the physical resources refer to two-dimensional resources in the time domain and frequency domain in the OFDM system.

The resource allocation above can be done by the base station, or by other network elements responsible for this function in the system. Part of the time-frequency resources may be reserved for bearing reference symbols in each frame, or part of the time-frequency resources may be reserved for reference symbols only in some frames. The above reference symbol time-frequency resources may be allocated in real time, or semi-statically or statically.

The base station determines a part of resources in the downlink control domain, and allocates reference symbol time-frequency resources for the base station and each relay station in the same cell in this part of resources, and the respective reference symbol time-frequency resources of the base station and each relay station occupy this part of resources The resource element positions for are different from each other. Figure 3 is a schematic structural diagram of a subframe with a common cyclic prefix (Cyclic Prefix, CP) length in the LTE system, where the rectangular area with a thick border is a physical resource block (resource block, RB for short) in the subframe. The RB occupies 7 OFDM symbols in the time domain and 12 subcarriers in the frequency domain. Each small square in the figure represents a resource element (resource element, RE for short). Assume that the physical downlink control field occupies the first 3 OFDM symbols in the subframe. The base station allocates reference symbol time-frequency resources to the base station and each relay station in the same cell in the downlink control domain resources except the time-frequency resources for sending common pilots.

When the base station and each relay station use a single antenna to send reference symbols, and the number of relay stations in the cell where the base station is located is N, the base station determines N+1 groups of resource elements from the time-frequency resources for sending common pilots in the downlink control domain to be used for The base station and N relay stations send reference symbols, and the base station and each relay station use one group respectively. The resource positions of each group are different from each other, and the number of resource elements occupied by each group is greater than or equal to 1.

In a Multiple-Input Multiple-Output (MIMO) channel, the reference symbols in the downlink control field can be sent only on one antenna port of the base station and/or each relay station, or can be sent on multiple antenna ports of the base station and/or each relay station. When the base station or the relay station transmits reference symbols on multiple antenna ports, and the number of antenna ports for transmitting reference symbols in the base station and each relay station is M in total, the base station determines from the time-frequency resources for sending common pilots from the resources in the downlink control domain The M groups are used to send reference symbols at M antenna ports, each antenna port for sending reference symbols uses one group, the resource positions of each group are different, and the number of resource elements occupied by each group is greater than or equal to 1.

In the LTE/LTE-A system, the physical resources for sending reference symbols in the downlink control domain can be allocated in units of control channel elements (Control Channel Element, CCE for short). In the downlink control channel in LTE, REs used to send control information are grouped in units of CCEs, each CCE has 9 resource-element groups (resource-element groups, REGs for short), and each REG has 4 REs. In LTE, after receiving the downlink control channel information, the terminal performs control information detection in units of CCEs, that is, the minimum unit for the terminal to detect control information is a CCE, so in this embodiment, the reference symbol time-frequency resources are allocated in units of CCEs For example, if 6 CCEs are used as mapping resources for reference symbols in the current downlink control domain, then a total of 36*6 REs can be obtained for mapping reference symbols. If the base station does not allocate reference symbol time-frequency resources in units of CCEs, the reference symbols will be scattered in the downlink control domain, which increases the difficulty of detecting terminals that do not support relay stations and detects control information in units of CCEs, making the terminal detection impossible. The probability of identifying the signal increases. When the base station allocates reference symbol time-frequency resources in units of CCEs, terminals that do not support relay station technology can easily determine whether the detected CCEs are information that they can identify, reducing the cost of detection control. The bit error detection rate of information.

In LTE and LTE-A systems, REGs are composed of REs distributed continuously in the frequency domain direction, and each REG must be located in the same OFDM symbol in the time domain. The distribution of multiple REGs belonging to the same CCE can be disrupted by certain rules, and it does not need to be continuously distributed in the frequency domain. The order of the resource elements occupied by the base station and each relay station in the frequency domain direction in each REG is preferably the same, so that the signaling overhead when the base station notifies the relay station of the resource is relatively small.

Step 202, the base station notifies the corresponding relay station of the allocation of reference symbol time-frequency resources of each relay station, and the base station and/or the relay station notifies the terminal of the allocation of reference symbol time-frequency resources through downlink signaling;

In step 203, the base station and each relay station transmit reference symbols on their respective reference symbol time-frequency resources, and the process ends.

When both the base station and the relay station map reference symbols on an antenna port, after the base station determines the resource positions used by the base station and each relay station, the base station and each relay station send their respective reference symbols at the allocated resource positions; each relay station corresponds to the base station No signal is sent at the resource position; a relay station sends reference symbols at its resource position in the allocation result, and the base station and other relay stations do not send any signal at the resource position corresponding to the relay station to ensure that the reference symbols sent by the base station and each relay station Do not interfere with each other.

In a multiple-input multiple-output channel, a base station or a relay station that transmits reference symbols on multiple antenna ports transmits reference symbols at the resource positions corresponding to the antenna ports through each antenna port, and the antenna ports of the base station or relay station are not in this antenna port. No signal is sent on the resource location of . For example, a relay station transmits reference symbols on the reference symbol time-frequency resource corresponding to the first antenna port at its first antenna port, other antenna ports of the relay station and the reference symbol time-frequency resources of the base station and other relay stations on the first antenna port No signal is sent on the resource, so as to ensure that the reference symbols sent by each antenna port do not interfere with each other. Therefore, the present invention is also applicable to the multi-antenna situation of the base station and the relay station.

The method in the present invention will be described in more detail below in conjunction with the accompanying drawings and examples.

Embodiment one:

As shown in Fig. 4, in the LTE-A system, the base station includes four relay stations in the same cell, which are respectively marked as RS1, RS2, RS3, and RS4. The system reserves resources in units of CCEs as mapping resources for base station and relay station reference symbols. The three thick-bordered rectangular areas in the figure are three resource groups (REGs) belonging to the same CCE in the current physical resource block, respectively marked as REG1, REG2 and REG3. The CCE is one of the CCEs in the reserved resources.

In this example, the base station does not transmit the reference symbols described in the present invention, and each relay station only transmits the reference symbols at one antenna port. In the figure, the resource elements filled with black dots indicate the positions of the resource elements where the four antenna ports of the base station are mapped to common pilot signals; A group of resource elements indicates the position of the reference symbol sent by RS2, a group of resource elements filled with horizontal lines indicates the position of the reference symbol sent by RS3, and a group of resource elements filled with square lines indicates the position of the reference symbol sent by RS4. The base station does not transmit any signal at the reference symbol resource positions corresponding to RS1, RS2, RS3 and RS4; RS1, RS2 and RS3 do not transmit any signal at the reference symbol resource positions corresponding to RS4; similarly, RS1, RS2 and RS4 are at the RS3 No signal is sent at the corresponding reference symbol resource position; RS1, RS3 and RS4 do not send any signal at the reference symbol resource position corresponding to RS2; RS2, RS3 and RS4 do not send any signal at the reference symbol resource position corresponding to RS1.

Embodiment two:

As shown in FIG. 4 , in the LTE-A system, the base station includes a relay station in the same cell, which is denoted as RS. The base station includes four antenna ports, and transmits reference symbols on the first and second antenna ports; the RS also transmits reference symbols on the two antenna ports respectively. In the figure, the resource elements filled with black dots represent the resource element positions where the four antenna ports of the base station are mapped to common pilot signals, and a group of resource elements filled with right slashes represent the positions where the base station sends reference symbols at the first antenna port. A group of resource elements filled with oblique lines indicates the position where the base station sends reference symbols at the second antenna port; a group of resource elements filled with horizontal lines indicates the position where RS sends reference symbols at its first antenna port, and a group of resource elements filled with square lines The resource element indicates where the RS transmits the reference symbol on its second antenna port. The third and fourth antenna ports of the base station do not transmit any signal at the above four reference symbol resource positions.

In summary, in a mobile communication system including a relay station, the method and the base station of the present invention can reduce the impact on the backward compatibility of the terminal, and by allocating different reference symbol time-frequency resources for the base station and each relay station, it can Collision of reference symbols between the base station and the relay station and between different relay stations is prevented when the base station and the relay station work on the downlink at the same time.

Of course, the above is only a specific implementation method of the present invention, and the present invention is not limited to the above-mentioned specific method. Without departing from the spirit and essence of the present invention, those skilled in the art can implement according to the present invention. Various corresponding changes and modifications are made, but these corresponding changes and modifications should belong to the protection scope of the appended claims of the present invention.

Claims (10)

1. A sending method of a reference symbol, characterized in that, The base station allocates reference symbol time-frequency resources to each relay station in the same cell in the downlink control domain and notifies the relay station that each relay station sends reference symbols on the reference symbol time-frequency resources allocated to it. 2. The method of claim 1, wherein The resource element positions occupied by the time-frequency resources of the respective relay station reference symbols in the downlink control domain are different from each other. 3. The method of claim 2, wherein When the relay station transmits reference symbols at multiple antenna ports, the base station allocates a reference symbol time-frequency resource for each antenna port that transmits the reference symbols in each relay station, and at the antenna port that transmits the reference symbols, the relay station is for the antenna port The reference symbols are transmitted on the reference symbol time-frequency resources allocated by the ports, and the resource element positions occupied by the reference symbol time-frequency resources corresponding to the antenna ports in the downlink control domain are different from each other. 4. The method of claim 1, wherein, The base station allocates reference symbol time-frequency resources for each relay station in the same cell as the base station and the base station in the downlink control domain, and notifies the relay station of the reference symbol time-frequency resources allocated for the relay station, and the base station and each The relay stations respectively send reference symbols on the reference symbol time-frequency resources allocated to them. 5. The method of claim 4, wherein, When allocating reference symbol time-frequency resources for the base station and each relay station in the same cell, the resource element positions occupied by the reference symbol time-frequency resources between the base station and each relay station and between different relay stations in the downlink control domain are different from each other. 6. The method of claim 5, wherein, When the base station and/or relay station transmits reference symbols on multiple antenna ports, the base station allocates reference symbol time-frequency resources to each antenna port that transmits reference symbols in the base station and/or each relay station, and the base station and/or each relay station The relay stations use the reference symbol time-frequency resources allocated to the antenna ports to send reference symbols at the respective antenna ports that transmit the reference symbols, and the resource element positions occupied by the reference symbol time-frequency resources corresponding to the antenna ports in the downlink control domain are mutually Are not the same. 7. The method of claim 1 or 4, wherein, The reference symbol time-frequency resource does not include the time-frequency resource for the base station to send common pilots in the downlink control domain; in the long-term evolution system and the advanced long-term evolution system, the reference symbol time-frequency resource in the downlink control domain is based on the control channel element units are allocated. 8. The method of claim 1 or 4, wherein, The base station and/or relay station also notifies the terminal of the allocation of the reference symbol time-frequency resource. 9. A base station, characterized in that, The base station includes a reference symbol time-frequency resource allocation module and a resource notification module; The reference symbol time-frequency resource allocation module is configured to allocate different resource element positions for each relay station in the same cell as the base station under the condition that the resource element positions occupied by the respective reference symbol time-frequency resources in the downlink control domain are different from each other. The relay station allocates reference symbol time-frequency resources; and notifies the resource allocation to the resource notification module; The resource notification module is configured to notify each relay station and/or terminal of the reference symbol time-frequency resource allocated to each relay station. 10. The base station according to claim 9, further comprising a reference symbol sending module; The reference symbol time-frequency resource allocation module is also used to ensure that the resource element positions occupied by the respective reference symbol time-frequency resources between the base station and each relay station in the same cell as well as each relay station in the downlink control domain are different from each other. Under the same conditions, allocate reference symbol time-frequency resources to the base station and each relay station; and send resource information allocated to the base station to the reference symbol sending module; The reference symbol sending module is further configured to send reference symbols on the reference symbol time-frequency resources allocated for the base station by the reference symbol time-frequency resource allocation module.

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