WO2011020357A1

WO2011020357A1 - Downlink synchronous transmission control method, system and coordinated multipoint transmission node

Info

Publication number: WO2011020357A1
Application number: PCT/CN2010/073237
Authority: WO
Inventors: 毛磊; 毕峰; 梁枫; 王斌
Original assignee: 中兴通讯股份有限公司
Priority date: 2009-08-17
Filing date: 2010-05-25
Publication date: 2011-02-24
Also published as: CN101626269A

Abstract

A downlink synchronous transmission control method, system and coordinated multipoint transmission node are provided in the invention. The method includes the following steps: a base station configures time-advance information, and sends the time-advance information to a coordinated multipoint transmission node; when the coordinated multipoint transmission node transmits a downlink signal, the initial time of the downlink transmission is advanced for a certain period of time according to the time-advance information. The invention enables multi-path signals reaching a user equipment (UE) to fall in a cyclic prefix (CP) receiving window more easily, thus increasing the amount of useful signals received by the UE and improving the receiving quality of the UE.

Description

Downlink synchronous transmission control method, system and cooperative multi-point transmission node

The present invention relates to the field of wireless communications, and in particular, to a downlink synchronous transmission control method, system, and CoMP (Coordinated Multiple Point) node in an LTE (Long Term Evolution) system.

Background technique

In 2005, 3GPP (3rd Generation Partnership Project) launched the LTE (Long Term Evolution) research working group to research and design 3.9G of the third generation mobile communication technology evolution (improved 3G) The next generation network.

LTE-Advanced (LTE Enhanced Technology) is a standard introduced by 3GPP to meet the requirements of the ITU (International Telecommunication Union) IMT-Advanced (4G). In March 2008, 3GPP adopted a research project on LTE-Advanced to further improve the LTE system to meet and exceed the ITU's technical requirements for IMT-Advanced, and to achieve backward compatibility of LTE. LTE-Advanced will be a candidate for IMT-Advanced submitted by the 3GPP to the ITU.

The LTE system has become one of the main candidate technologies for IMT-Advanced because it represents the main direction of the development of new mobile communication technologies. LTE itself can serve as the technical foundation and core for meeting the needs of IMT-Advanced, but purely in terms of indicators, there is still a gap between LTE and IMT-Advanced requirements. Therefore, when upgrading LTE to 4G, it does not need to change the core of the LTE standard, but only needs to be expanded, enhanced, and improved on the basis of LTE to meet the requirements of IMT-Advanced. The main technologies introduced include Relay (中Next, CoMP (Coordinated Multiple Point), CA (Carrier Aggregation) and other enhancement technologies. At present, in order to improve the coverage gain of the cell boundary and achieve the blinding effect, in 3GPP

Relay technology is introduced in LTE-Advanced, and its model architecture is shown in Figure 1. Each of the eNBs (evolved Node B, the improved Node B) provides services for the User Equipment (User Equipment) of the cell, and also performs data transmission and signaling interaction with several Relays under its control. Similarly, each Relay communicates with both the eNB and the UE under the Relay. The eNB to the Relay link and the Relay to its serving UE link can use the same frequency resource, which is called an in-band relay. It can also use different frequency resources, which is called an out-of-band relay. CoMP is precisely the goal of IMT Advanced. It is reduced by multiple multi-point cooperation methods such as different radio access point (RRU) cooperation in the base station, base station and its relay cooperation and inter-base station cooperation. Technical measures for cell edge interference, improving cell edge spectrum efficiency, and increasing effective coverage.

OFDM (Orthogonal Frequency Division Multiplexing) technology is adopted in the LTE system, which requires that uplink signals sent by multiple UEs can reach the receiving end of the base station at the same time, and multiple arrival delays are within the CP (cyclic prefix) range. The signal can be demodulated as a useful signal, and the signal falling outside the CP window will become interference. Therefore, a strict uplink synchronization process has been designed in the existing LTE system. In the random access process, the base station calculates the time that the UE uplink signal needs to be sent in advance by measuring the time that the UE transmits the Preamble (preamble) to the base station. And carrying the Timing Advance Command information to the UE through the random access response. In the connection state, the eNB and the UE perform some measurements, and determine whether the uplink transmission time of the UE needs to be updated according to the measurement result, for example: using the radio link quality measurement to determine whether the link is out of step, using an absolute threshold. The quality of the radio link is determined. The terminal can also detect the quality of the RS (Reference Signal) and the Physical Control Format Indicator Channel (PCFICH) and report the link quality problem to the upper layer. The detection cycle of the terminal is specified in the standard. In the prior art, a control element is designed at the MAC (Media Access Control) layer to carry the Timing Advance Command indication.

The UE starts to use the new value as the time when the uplink signal is transmitted in advance in the sixth subframe after receiving the indication information. For the downlink signals, since the signals are uniformly transmitted by the eNB, the time of sending signals to each UE can be completely consistent. Therefore, it is not necessary to design a synchronization process for downlink data transmission in the current LTE system. The UE can determine the reception according to the synchronization signal and the pilot signal transmitted by the system. The time of the line signal.

SUMMARY OF THE INVENTION The technical problem to be solved by the present invention is to provide a downlink synchronization transmission control method, system, and a coordinated multi-point transmission node, which can make a multipath signal arriving at a UE more likely to fall within a CP reception window, and increase UE reception. Useful semaphore. In order to solve the above technical problem, the present invention provides a downlink synchronization transmission control method, which is applied to a system using a coordinated multipoint transmission mode, including: a base station configuring time advance information, and transmitting the information to a coordinated multipoint transmission node; When transmitting the downlink signal, the multipoint transmission node advances the start time of the downlink transmission by a specific time according to the time advance information.

Preferably, the time advance information is a signal transmission time at the distance determined by the base station according to a distance to the coordinated multipoint transmission node; and the step of advancing the start time of the downlink transmission by a coordinated multipoint transmission node by a specific time The coordinated multipoint transmission node advances the start time of the downlink transmission by the signal transmission time. Preferably, the method further includes: when the location of the coordinated multipoint transmission node is fixed, the base station obtains a distance of the base station to the coordinated multipoint transmission node by measuring a path loss, or performs operation and maintenance. The interface is configured by the operator to configure the distance value of the base station to the coordinated multipoint transmission node to the base station; when the location of the coordinated multipoint transmission node is not fixed, the base station obtains a periodic path loss measurement. The distance from the base station to the coordinated multipoint transmission node. Preferably, in the step of configuring the time advance information by the base station, the base station determines the signal transmission time according to the distance of the base station to the coordinated multipoint transmission node divided by the propagation speed of the light. Preferably, the method further includes: adjusting the time advance information as follows: subtracting the time advance information from the base station to the mobile terminal and the coordinated multipoint transmission node to the mobile terminal Difference in distance The transmission delay; wherein, the distance from the base station to the mobile terminal, and the distance from the coordinated multipoint transmission node to the mobile terminal are obtained by using a positioning technique or a path loss measurement. Preferably, in the step of being sent to the coordinated multipoint transmission node, the base station sends the time advance information to the coordinated multipoint transmission by using a timing advance indication of the medium access control layer or radio resource control signaling. node. Preferably, the time advance information is half of a timing advance for uplink coordinated synchronization of the coordinated multipoint transmission node; and the step of advancing a start time of the downlink transmission by a coordinated multipoint transmission node by a specific time, The cooperative multipoint transmission node advances the start time of the downlink transmission by the time advance information. In order to solve the above technical problem, the present invention provides a downlink synchronization transmission control system, including a base station and a coordinated multipoint transmission node, the base station includes a downlink synchronization configuration module, and the coordinated multipoint transmission node includes a downlink synchronization control module, where: The downlink synchronization configuration module is configured to: configure time advance information, and send the information to the coordinated multipoint transmission node; the downlink synchronization control module is configured to: when transmitting the downlink signal, downlink transmission according to the time advance information The start time is advanced a specific time.

Preferably, the time advance information configured by the downlink synchronization configuration module is a signal transmission time determined according to a distance from the base station to the coordinated multipoint transmission node; the downlink synchronization control module is The method is configured to: according to the received signal transmission time, when the downlink signal is transmitted, advance the start time of the downlink transmission by the signal transmission time. Preferably, the downlink synchronization configuration module is further configured to: derive a distance of the base station to the coordinated multipoint transmission node by path loss measurement; and divide by a distance of the base station to the coordinated multipoint transmission node by The propagation speed of the light determines the signal transmission time. Preferably, the downlink synchronization configuration module is further configured to: after obtaining a distance between the base station and the mobile terminal by using a positioning technology or a path loss measurement, and a distance between the coordinated multipoint transmission node and the mobile terminal, Determining a distance between the base station and the mobile terminal and the coordinated multipoint transmission a transmission delay of a distance difference between the node and the mobile terminal; and adjusting the time advance information as follows: subtracting the transmission delay from the time advance information. Preferably, the time advancement information configured by the downlink synchronization configuration module is half of a time advancement amount used for uplink synchronization of the coordinated multipoint transmission node; the downlink synchronization control module is configured to: according to the received The time advance amount, when transmitting the downlink signal, advances the start time of the downlink transmission by the time advance information. In order to solve the above technical problem, the present invention provides a coordinated multipoint transmission node, including a downlink synchronization control module, where: the downlink synchronization control module is configured to: when transmitting a downlink signal, downlink transmission according to the time advance information The start time is advanced a certain time. Preferably, the time advance information configured by the downlink synchronization configuration module is a signal transmission time determined according to a distance from the base station to the coordinated multipoint transmission node; the downlink synchronization control module is The method is configured to: according to the received signal transmission time, when the downlink signal is transmitted, advance the start time of the downlink transmission by the signal transmission time.

The present invention is applicable to a scenario in which a Relay node, a CoMP node, or a neighboring eNB cooperates with a serving eNB to transmit a signal. By controlling the signal transmission time of a Relay node, a CoMP node, or a neighboring eNB, the multipath signal arriving at the UE can fall more easily. In the CP receiving window, the useful signal amount received by the UE is increased, and the receiving quality of the UE is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of the architecture of a Relay transmission model; FIG. 2 is a schematic diagram of a cooperative multipoint transmission (CoMP) model; FIG. 3 is a schematic diagram of a downlink time synchronization correspondence relationship under a Relay transmission model; And the relative position of the UE is shown in FIG. 1; FIG. 5 is a schematic diagram 2 of the relative positions of the eNB, the Relay, and the UE; FIG. 6 is a schematic diagram of a downlink synchronous transmission control system according to an embodiment of the present invention.

A preferred embodiment of the present invention is shown in FIG. 2. In LTE-A, since new nodes (such as Relay, CoMP, etc.) are introduced, these nodes not only receive signals but also transmit signals to the UE, which is important. The application is that these nodes and eNBs transmit the same signal at the same time to enhance the UE's reception. This method is called cooperative transmission. In the process of cooperative transmission, since the eNB and multiple nodes simultaneously transmit downlink signals, if the transmission time is not controlled, the time difference of multipath signals arriving at the UE may be relatively large, and most of the signals may not fall within the CP window, and the useful signals are weakened. The interference signal becomes stronger, which ultimately affects the reception quality of the UE, and reduces the performance gain brought by the Relay/CoMP technology. The technical solution of the present invention is further described in detail below by taking a Relay node as an example. Since the Relay performs the function of the UE at some time, the Relay can obtain the timing information by using the downlink synchronization acquisition process of the existing UE. For example, through the cell search procedure, the PSS (Primary Synchronization Signal), SSS (Secondary Synchronization Signal), and Downlink Pilot Channel transmitted by the eNB can be searched for time synchronization. As can be seen from FIG. 3, there is an eNB-to-Relay and eNB-to-UE signal transmission delay between the time maintained by the Relay and the UE and the time maintained by the eNB. When the eNB and the Relay cooperate to transmit signals, the Relay transmits the signal according to the downlink time of the eNB received by itself, and the transmission time is actually compared with the transmission time of the eNB. The transmission delay of one eNB to the Relay is delayed. When the eNB and the Relay cooperate to transmit a signal, the Relay is a CoMP node. As shown in FIG. 4, in the downlink cooperative transmission, if both the eNB and the relay transmit according to their own time, from the position of the UE, the paths through which the two signals pass are B and C, respectively, then the two signals arrive at the UE. The time difference is caused by the difference in distance of C-(BA). The time difference is also related to the location where the UE is located. As for FIG. 5, the time difference between the signal transmitted by the eNB and the Relay reaching the UE is greater. In order to make the signal arrive at the UE more accurately, the Relay needs to advance the signal for a certain time to compensate for the error between the downlink time maintained by itself and the downlink time of the eNB. How long in advance can be determined by the following method: First, the distance from the eNB to the relay (A), the distance from the eNB to the UE (B), and the distance from the Relay to the UE (C) need to be determined separately; and then the eNB and the Relay are determined. The transmitted signal arrives at the UE with a distance difference C-(BA), and according to the propagation speed of the light, the signal transmission time on the distance difference is calculated, and the signal transmission time is signaled to the Relay, and the Relay transmits the downlink signal. The signal transmission time is transmitted in advance based on the start time of the downlink subframe maintained by itself. In this way, it can be ensured that the signals transmitted by the eNB and the Relay arrive at the UE synchronously. However, in the above method, since the UE is always in a mobile state, its location is not fixed, and thus the distance between the eNB and the Relay to the UE is always in a certain change. Therefore, the above method is relatively difficult to determine the distance from the eNB to the UE (B). ), and the distance from Relay to UE (C).

In the present invention, it is considered that since the UE side can receive the signal, the CP can be used as the allowable range of the time difference of the different path arrival time. Therefore, the delay of the downlink downlink synchronization transmission time can be estimated to be relatively thicker, and the downlink is not downlinked. Signal pre-emission can still provide better signal reception performance. Based on the above considerations, in the embodiment of the present invention, the following steps are used to implement control of downlink synchronous transmission: The eNB configures a time advance information and notifies the Relay;

The Relay controls its downlink transmission time according to the synchronization signal of the eNB and the time advance information.

The time advance information may be determined according to the distance from the eNB to the relay. Generally speaking,

The location of the relay node is fixed. In this case, the distance from the eNB to the relay can be obtained through path loss measurement, or the fixed distance value is configured by the operator to the base station through the operation and maintenance interface. If Relay In the mobile state, the distance from the eNB to the Relay can be calculated by periodically measuring the path loss between the eNB and the Relay. The eNB configures the time advance information by: calculating the distance from the eNB to the relay according to the path loss measurement, and calculating the signal transmission time T at the distance according to the optical propagation speed, and notifying the relay by signaling the time T. When transmitting the downlink signal, the Relay transmits the time T based on the start time of the downlink subframe maintained by itself. In this way, the signal transmitted by the Relay and the signal transmitted by the eNB can be basically guaranteed to be at the same starting time. When the two signals arrive at the UE position, the time difference will decrease, and it is easier to fall into the signal detection window of the UE. After the time advance information is determined, the eNB may send the information to the Relay through the control element of the MAC layer. The information may also be sent to the Relay through the RRC (Radio Resource Control) signaling format.

When the relay receives the information, it controls the time of transmitting the signal according to the configured/or calculated downlink advance time when transmitting the UE signal.

Further, if the cell radius is large, the eNB can further make some adjustments based on the above estimated signal transmission time T. For example, when the cell radius is large, the location of the UE is farther away from the eNB than the eNB. At this time, the eNB can subtract the transmission delay of the eNB to the UE to the UE to the UE path difference based on the time T.

In addition, the foregoing time advance information may also be sent by the eNB.

Half of the timing advance in the Timing Advance Command of the step, the Relay estimates the time required to advance the start time of the downlink transmission signal during cooperative transmission according to the timing advance, for example, but not limited to: Advance the downlink transmission start time The time advance information is used to implement control of downlink synchronous transmission.

The method of the present invention is not limited to the Relay scenario, and is applicable when applying other CoMP nodes for cooperative transmission. For example, for the coordinated transmission mode between the eNBs, according to the distance between the cooperative eNB and the serving eNB (determined at the time of cell planning), and the location of the UE (by positioning technology or measurement information of the UE, such as path loss, etc.), Serving eNB configures a time advance The information is transmitted to the cooperative eNB through the x2 interface, and the cooperative eNB transmits the signal according to the received time advance information when the signal is transmitted.

As shown in FIG. 6, the embodiment of the present invention further provides a downlink synchronous transmission control system, including a base station 61 and a coordinated multipoint transmission node 62. The base station 61 further includes a downlink synchronization configuration module 611 and a coordinated multipoint transmission node 62. Further, a downlink synchronization control module 621 is configured, wherein the downlink synchronization configuration module 611 is configured to: configure time advance information and send the information to the coordinated multipoint transmission node 62; the downlink synchronization control module 621 is configured to: when transmitting the downlink signal, according to The time advance information advances the start time of the downlink transmission by a certain time.

The time advance information configured by the downlink synchronization configuration module 611 may refer to a signal transmission time determined according to the distance from the base station 61 to the coordinated multipoint transmission node 62. The downlink synchronization control module 621 is configured to: receive according to When the downlink signal is transmitted, the start time of the downlink transmission is advanced by the signal transmission time. Further, the downlink synchronization configuration module 611 is further configured to: derive the distance from the base station 61 to the coordinated multipoint transmission node 62 by path loss measurement; and determine by dividing the distance from the base station 61 to the coordinated multipoint transmission node 62 by the propagation speed of the light. Signal transmission time. In addition, the downlink synchronization configuration module 611 is further configured to: determine the distance from the base station 61 to the mobile terminal by using the positioning technology or the path loss measurement, and determine the distance from the coordinated multipoint transmission node 62 to the mobile terminal, and determine the base station 61 to the mobile terminal. The transmission delay on the distance difference from the coordinated multipoint transmission node 62 to the mobile terminal; and the time advance information is adjusted as follows: The time advance information is subtracted from the transmission delay.

In addition, the time advance information configured by the downlink synchronization configuration module 611 may also refer to half of the timing advance for the uplink synchronization of the coordinated multipoint transmission node 62; At this time, the downlink synchronization control module 621 is configured to: according to the received timing advance, when transmitting the downlink signal, advance the start time of the downlink transmission by the time advance information.

While the invention has been described in connection with the specific embodiments, the modifications and variations may be Such modifications and variations are considered to be within the scope of the invention and the scope of the appended claims.

INDUSTRIAL APPLICABILITY The present invention provides a downlink synchronous transmission control method and system, and a coordinated multi-point transmission node. The signal transmission time of the CoMP node enables the multipath signal arriving at the UE to fall more easily in the CP reception window, thereby increasing The useful signal amount received by the UE improves the reception quality of the UE.

Claims

Claim

A downlink synchronous transmission control method, which is applied to a system using a coordinated multi-point transmission mode, comprising: a base station configuring time advance information, and transmitting the information to a coordinated multi-point transmission node; When the signal is received, the start time of the downlink transmission is advanced by a specific time according to the time advance information.

2. The method according to claim 1, wherein: the time advance information is a signal transmission time at the distance determined by the base station according to a distance to the coordinated multipoint transmission node; and the downlink transmission is performed at the coordinated multipoint transmission node. The step of advancing the start time by a specific time advances the coordinated multipoint transmission node by the start time of the downlink transmission by the signal transmission time.

3. The method according to claim 2, the method further comprising: when the location of the coordinated multipoint transmission node is fixed, obtaining, by the base station, the base station to the coordinated multipoint transmission by measuring a path loss The distance of the node, or the distance value of the base station to the coordinated multipoint transmission node is configured by the operator to the base station through the operation and maintenance interface; when the location of the coordinated multipoint transmission node is not fixed, the base station passes The periodic path loss measurement results in the distance of the base station to the coordinated multipoint transmission node.

The method according to claim 2 or 3, wherein: in the step of configuring time advance information by the base station, the base station determines, according to the distance from the base station to the coordinated multipoint transmission node, by the propagation speed of the light The signal transmission time.

5. The method of claim 1, 2 or 3, the method further comprising

Performing the following adjustment on the time advance information: subtracting the time advance information from the distance from the base station to the mobile terminal and the distance difference between the coordinated multipoint transmission node and the mobile terminal The transmission delay; wherein, the distance from the base station to the mobile terminal, and the distance from the coordinated multipoint transmission node to the mobile terminal are obtained by using a positioning technique or a path loss measurement.

6. The method according to claim 1, 2 or 3, wherein: in the step of transmitting to the coordinated multipoint transmission node, the base station passes the time advance indication of the medium access control layer, or the radio resource control signaling The time advance information is sent to the coordinated multipoint transmission node.

7. The method according to claim 1, wherein: said time advance information is half of a time advance for uplink coordinated synchronization of said coordinated multipoint transmission node; and a start of downlink transmission at a coordinated multipoint transmission node In the step of advancing the time by a specific time, the coordinated multipoint transmission node advances the start time of the downlink transmission by the time advance information.

A downlink synchronous transmission control system, comprising: a base station and a coordinated multipoint transmission node, the base station includes a downlink synchronization configuration module, and the coordinated multipoint transmission node includes a downlink synchronization control module, where: the downlink synchronization configuration module is configured. The time synchronization information is configured and sent to the coordinated multipoint transmission node; the downlink synchronization control module is configured to: when transmitting the downlink signal, advance the start time of the downlink transmission by a specific time according to the time advance information time.

9. The system according to claim 8, wherein: the time advance information configured by the downlink synchronization configuration module is a signal at the distance determined according to a distance from the base station to the coordinated multipoint transmission node. The downlink synchronization control module is configured to: advance the start time of the downlink transmission by the signal transmission time when transmitting the downlink signal according to the received signal transmission time.

10. The system according to claim 9, wherein: the downlink synchronization configuration module is further configured to: derive a distance of the base station to the coordinated multipoint transmission node by path loss measurement; and according to the base station to the The signal transmission time is determined by dividing the distance of the coordinated multipoint transmission node by the propagation speed of the light.

11. The system of claim 8, 9 or 10, wherein: the downlink synchronization configuration module is further configured to: derive a distance of the base station to the mobile terminal by using a positioning technique or a path loss measurement, and After coordinating the distance of the multi-point transmission node to the mobile terminal, determining a transmission delay of a distance between the base station and the mobile terminal and a distance difference between the coordinated multi-point transmission node and the mobile terminal; The time advance information is adjusted as follows: The time advance information is subtracted from the transmission delay.

The system according to claim 8, wherein: the time advance information configured by the downlink synchronization configuration module is half of a time advancement amount used for uplink synchronization of the coordinated multipoint transmission node; The control module is configured to: advance the start time of the downlink transmission by the time advance information when transmitting the downlink signal according to the received timing advance.

A coordinated multi-point transmission node, comprising: a downlink synchronization control module, wherein: the downlink synchronization control module is configured to: when transmitting the downlink signal, advance a start time of the downlink transmission by a specific time according to the time advance information .

The cooperative multipoint transmission node according to claim 13, wherein: the time advance information configured by the downlink synchronization configuration module is determined according to a distance from the base station to the coordinated multipoint transmission node. The downlink synchronization control module is configured to: advance the start time of the downlink transmission by the signal transmission time when transmitting the downlink signal according to the received signal transmission time.