JP2014090508A - Method and device for implementing uplink synchronization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for establishing uplink (UL) synchronization.SOLUTION: Embodiments of the invention provide a method and device for establishing uplink (UL) synchronization. The method comprises: instructing a UE to perform a dedicated PRACH transmission; calculating a timing advance (TA) according to first timing information derived by itself and second timing information received from a plurality of non-serving base stations; and sending the timing advance to the UE to enable the UE to establish the uplink synchronization with involved base stations according to the timing advance. The first timing information and the second timing information are associated with propagation delays of the dedicated PRACH transmission performed by the UE.

Description

  The present invention relates to wireless communication technology, and more particularly to a method and device for implementing uplink synchronization.

  Uplink (UL) multi-point coordination (CoMP) was accepted at 36.814 as an important candidate for improving UL capacity in LTE Advanced Systems. In UL CoMP, a plurality of base stations (BS) are configured to receive UL transmission from a UE, and received signals are combined to obtain a combined gain. The most important baseline for the UL CoMP implementation is that all involved base stations must be able to receive UL transmissions from the UE, i.e. to resolve different propagation delays between the UE and the involved base stations. The UE should perform UL synchronization with all involved base stations before UL transmission. For example, as shown in FIG. 6, if UL CoMP is to be implemented, this problem due to the difference between propagation delays t1 and t2 for the involved base stations BS1 and BS2 must be solved.

  Generally speaking, UL synchronization means that the UE's transmission arrives at the relevant base station within the coverage of the relevant base station's cyclic prefix (CP); If the base station is reached before or after the CP coverage, the affected base station will not be able to correctly decode this UL transmission and therefore will not be able to achieve UL CoMP. In this case, a feasible solution is given to solve this problem. In order to ensure that the UL transmission of the UE reaches the base station during the coverage of the base station CP, the direct method is to design a longer CP to eliminate the effects of different propagation delays. . As shown in FIG. 7, in FIG. 7, the UL transmission for both BS1 and BS2 is within the coverage of the CP. However, this solution has the following drawbacks.

1. It is very difficult to determine the optimal CP length to cover various UL CoMP scenarios. For example, in scenarios where the propagation delay is similar for the base stations involved, a short CP length is sufficient, but not applicable to scenarios where the propagation delay changes dramatically. Furthermore, long CPs are a waste of resources in scenarios where propagation delays are similar.
2. This long CP increases overhead and results in loss of UL capacity. The reason is that the symbols to be used for transmitting data are in this case occupied by the extended CP.
3. This solution cannot support legacy UEs.
4). Since UL CoMP can only be scheduled for frames with a long CP length, scheduling flexibility is limited.

  Embodiments of the present invention propose a method and system for establishing UL synchronization to solve the above problems.

  According to one aspect of the present invention, a method for establishing uplink synchronization is provided. The method directs the UE to perform dedicated PRACH transmissions and timing advance according to first timing information derived from itself and second timing information received from a plurality of non-serving base stations. Calculating (TA), transmitting a timing advance to the UE, and allowing the associated base station and the UE to establish uplink synchronization according to the timing advance, the first timing information and the second Timing information is associated with the propagation delay of dedicated PRACH transmissions implemented by the UE.

  According to another aspect of the invention, a trigger unit that instructs the UE to perform dedicated PRACH transmission, and a base station transceiver unit configured to send a command from the trigger unit to the UE; A propagation delay estimation unit configured to estimate a propagation delay based on detection of a dedicated PRACH transmission performed by the UE to derive the first timing information; a first timing information; Configured to calculate a timing advance (TA) according to the second timing information received by the transceiver unit (220) from the serving base station and send the timing advance to the UE through the base station transceiver unit TA calculation unit, first timing information and second timing Distribution is, the base station including the TA calculation unit associated with the propagation delay of dedicated PRACH transmission is performed by the UE is provided.

  According to another aspect of the invention, a propagation delay is estimated according to a detection unit configured to detect a dedicated PRACH transmission from the UE and a dedicated PRACH transmission detected by the detection unit to derive timing information. And a delay estimation unit configured to transmit timing information to the serving base station of the UE through the detection unit and to calculate a timing advance is provided.

  According to another aspect of the invention, a UE transceiver unit configured to receive a dedicated PRACH transmission command and TA from a UE's serving base station, wherein the TA is derived by the UE's serving base station itself. Calculated by the serving base station of the UE according to both the timing information of the propagation delay of the dedicated PRACH transmission performed by the UE and the timing information of the propagation delay of the dedicated PRACH transmission performed by the UE received from other base stations. Timing transceiver advance UE transceiver unit, PRACH transmission unit configured to perform dedicated PRACH transmission according to received dedicated PRACH transmission command, and configured to perform uplink transmission according to received TA Including a UL transmission unit The equipment (UE) is provided.

  According to another aspect of the present invention, there is provided a communication system comprising the above base station and user equipment.

  Based on the above solution, it is easy to establish synchronization between the UE and all relevant base stations for UL CoMP, and without modification to the UE software, hardware or protocol It is an advantage line in that compatibility is supported and that there is no impact on capacity and scheduling flexibility because there is no need to extend the CP.

  The advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

1 is a schematic diagram of a system for UL CoMP according to an embodiment of the present invention; FIG. 3 is a block diagram of a serving base station for UL CoMP according to an embodiment of the present invention. FIG. 3 is a block diagram of a non-serving base station for UL CoMP according to an embodiment of the present invention. FIG. 4 is a block diagram of a UE for UL CoMP according to an embodiment of the present invention. 4 is a flow diagram of a method for UL CoMP according to an embodiment of the present invention. Fig. 6 is a schematic illustration of propagation delays between a UE and different base stations. 1 is a schematic diagram of a scheme for dealing with different propagation delays of the prior art.

  Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In order not to obscure an understanding of the present invention, the description omits details and features that are not necessary for the present invention.

  In one embodiment of the present invention, the system for uplink synchronization shown in FIG. 1 is proposed, which includes the following base stations and user equipment (UE):

  In addition, the base station shown in FIG. 2 is proposed, and the base station is configured to instruct the UE to perform a dedicated physical random access channel (PRACH) transmission, and a trigger unit. Base station transceiver unit 220 configured to send instructions from the UE to the UE and estimate propagation delay based on detection of dedicated PRACH transmission performed by the UE to derive first timing information Calculating a timing advance according to the propagation delay estimation unit 230 configured as described above, first timing information, and second timing information received by the transceiver unit 220 from a plurality of non-serving base stations (NSBS). , Timing advance to UE through base station transceiver unit 220 And a timing advance (TA) computation unit 240, configured to send the first timing information and the second timing information is associated with a propagation delay of dedicated PRACH transmission is performed by the UE.

  The base station receives uplink transmissions directly from the UE through the base station transceiver unit 220, forwards by multiple non-serving base stations, and receives uplink transmissions performed by the UE according to established uplink synchronization. , Further comprising a multi-point coordination main unit 250 configured to combine uplink transmissions received directly from the UE and uplink transmissions forwarded by a plurality of non-serving base stations to implement CoMP transmissions .

  The base station includes non-serving base station second timing information when the non-serving base station includes a non-serving base station that makes it impossible to generate a timing advance for establishing uplink synchronization. Further includes a selection unit 260 configured to exclude. The TA calculation unit is further adapted to recalculate the timing advance according to the first timing information and the second timing information provided by the remaining non-serving base stations remaining in the plurality of non-serving base stations after exclusion. Composed.

  The base station further includes a storage unit 270 configured to store a dedicated PRACH random access code. The trigger unit 210 further selects an unused dedicated PRACH random access code from the storage unit 270 and transmits it to the UE through the base station transceiver unit 220 to the unused dedicated PRACH random access code. And configured to request the UE to perform dedicated PRACH transmission. The trigger unit 210 is further configured to notify the selected non-used dedicated PRACH random access code through the base station transceiver unit 220 to a plurality of non-serving base stations.

  In addition, the base station shown in FIG. 3 is proposed, which is detected by the detection unit 310 to derive the timing information and the detection unit 310 configured to detect the dedicated PRACH transmission from the UE. A delay estimation unit 320 configured to estimate propagation delay according to dedicated PRACH transmission, transmit timing information to the serving base station of the UE through detection unit 310, and calculate timing advance.

  Further, the detection unit 310 is further configured to receive information of the first dedicated random access code from the serving base station. If the detected dedicated PRACH transmission includes a second dedicated random access code that is identical to the first dedicated random access code, the delay estimation unit 320 may further detect the dedicated information to derive timing information. It is configured to estimate the propagation delay of the PRACH transmission.

  The detection unit 310 further detects an uplink transmission performed by the UE after uplink synchronization is established according to timing advance, forwards the detected uplink transmission to the UE's serving base station, and performs CoMP transmission Configured as follows.

  Further, the user equipment (UE) shown in FIG. 4 is proposed, wherein the UE is a UE transceiver unit 410 configured to receive a dedicated PRACH transmission command and TA from the UE's serving base station, where the TA is Both the propagation delay timing information of the dedicated PRACH transmission performed by the UE derived by the UE serving base station itself and the timing information of the propagation delay of the dedicated PRACH transmission performed by the UE received from other base stations In accordance with the received TA, the UE transceiver unit 410 being a timing advance calculated by the serving base station of the UE, the PRACH transmission unit 420 configured to perform dedicated PRACH transmission according to the received dedicated PRACH transmission command, To carry out UL transmission And a UL transmission unit 430 that is configured.

  Although the base station and the UE in the embodiment of the present invention are described by separate functional modules, in an actual application example, each component illustrated in FIGS. 2 to 4 can be implemented by a plurality of devices. In applications, multiple components shown in the accompanying figures can be integrated into a single chip or a single device. The base station and UE may further include any other units and means for other purposes.

  The specific structure and operation process of the above-described base station and user equipment (eg, UE) will now be described in detail in conjunction with FIG. In the UL CoMP scenario, one embodiment of the present invention utilizes a contention-free PRACH transmission strategy. Specific steps are shown in FIG.

  In step S510, the serving base station (SBS) trigger unit 210 selects an unused dedicated random access code from its dedicated RACH preamble pool and passes it through the base station transceiver unit 220 to all relationships. To notify non-serving base stations. The serving base station also requests the UE to perform a dedicated PRACH transmission based on the selected dedicated random synchronization code.

  In step S520, the PRACH transmission unit 420 of the UE performs dedicated PRACH transmission accordingly.

  In step S530, the detection unit 310 of the non-serving base station detects the dedicated PRACH transmission, and the delay estimation unit 320 estimates the propagation delay according to the detected dedicated PRACH transmission. At the same time, the serving base station propagation delay estimation unit 230 estimates the propagation delay according to the dedicated PRACH transmission detected by the base station transceiver unit 220. When the dedicated PRACH random access code received from the UE by the non-serving base station is the same as that received from the serving base station, the non-serving base station reports propagation delay estimation timing information through the transmission unit 420. .

  In step S540, the TA calculation unit 240 of the serving base station receives the received timing information (ie the second New TA command is determined according to the timing information) and the timing information estimated by the propagation delay estimation unit 230 (ie, the first timing information). The serving base station then delivers the TA command to the UE through the base station transceiver unit 220.

  In step S550, the UL transmission unit 430 of the UE performs UL synchronization of all relevant base stations using the TA command received by the UE transceiver unit.

  After establishing UL synchronization, the UE can initiate UL transmission. If the detection unit 310 of the non-serving base station detects the UL transmission, the UL transmission is transferred to the serving base station. The serving base station receives the UL transmission from the UE and the UL transmission transferred by the non-serving base station through the base station transceiver unit 220 and combines them by the multipoint coordination unit 250.

  The solution provided by embodiments of the present invention can also be used to determine whether a UE can utilize UL CoMP technology. For example, if the serving station cannot find a TA command that can ensure that the UL transmission reaches the base station within the shortest / longest propagation delay of the coverage of the CP, it receives the UL transmission of the UE. The UE cannot use UL CoMP because there is a base station that cannot be used. Alternatively, from another perspective, this solution can select an appropriate base station to provide service for the UE. For example, the serving base station selection unit 260 may select a base station whose CP can cover the UE's UL transmission and put it in the UE's UL CoMP set.

  For the UL CoMP implementation in an embodiment of the present invention, the baseline is that the UE establishes UL synchronization for all participating base stations. As shown in FIG. 1, all involved base stations are pre-defined to measure their propagation delay for the UE, exchange propagation delay information, and the UE's UL transmissions are all covered by its CP. Generated timing advance command. In FIG. 1, it is assumed that t4 is the shortest propagation delay and t3 is the maximum propagation delay. The TA command can then be sought to guarantee UL transmission arrival to BS4 and BS3 within the coverage of the CP. For example, UL transmission reaches BS4 at the beginning of CP and BS3 at the end of CP. It is clear that UL transmission also reaches BS1 and BS2 within the coverage of the CP. Thus, UL synchronization is established between the UE and all relevant BSs.

  In the above solution, from the UE perspective, the UE needs to perform dedicated PRACH transmission, adopt a new TA command, and perform UL transmission when a new TA command is received. is there. Compared to the general UE operation in LTE, no modifications to the protocol or software are required. In this respect, backward compatibility is supported by the solution proposed by the present invention. Furthermore, since the normal CP length is employed, there is no effect on additional overhead or UL capacity.

  Those skilled in the art will immediately appreciate that the various steps of the above method can be performed by a programmed computer. As used herein, certain embodiments can include machine-readable or computer-readable program storage devices, such as digital data storage media, and encoded program instructions executable by the machine or computer, wherein the instructions are as described above. Perform some or all of the method steps. The program storage device may be, for example, a digital memory, a magnetic storage medium such as a magnetic disk or magnetic tape, a hard drive, or an optically readable digital data storage medium. Embodiments are also intended to encompass a computer programmed to perform the steps of the method described above.

  The description and drawings merely illustrate the principles of the invention. Thus, although not explicitly described or illustrated herein, it will be understood that those skilled in the art can devise various arrangements that implement the principles of the invention and fall within the spirit and scope of the invention. Moreover, all examples described herein are primarily for teaching purposes only to assist the reader in understanding the principles and concepts of the invention that the inventors have contributed to advancing the art. It is expressly intended that it should not be construed as a limitation on the examples and conditions so specifically described. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

  The foregoing description serves only as an embodiment for practicing the invention, and any modifications or local substitutions that do not depart from the scope of the invention are within the scope of the invention as defined by the claims. It should be understood by those skilled in the art. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (1)

A method performed by a serving base station cooperating with a non-serving base station to establish uplink synchronization, comprising:
Instructing user equipment (UE) to perform dedicated physical random access channel (PRACH) transmission;
Calculating a timing advance (TA) according to first timing information derived by the serving base station and second timing information received from a plurality of non-serving base stations;
Transmitting the timing advance to the UE and allowing the associated base station and the UE to establish the uplink synchronization according to the timing advance;
The first timing information and the second timing information are associated with a propagation delay of the dedicated PRACH transmission performed by the UE;
Method.

Images