CN110858989A - Inter-cell switching method and system based on repeated transmission of physical channel - Google Patents

Abstract

The present application discloses a method and system for inter-cell handover based on repeated transmission of physical channels, wherein the method includes: when an inter-cell handover of a user equipment (UE) needs to be performed, the source cell converts the reference signal received power of the UE to the target cell. The RSRP measurement value is notified to the target cell; the target cell determines the coverage level of the UE in the target cell according to the RSRP measurement value, and uses the coverage level and the coverage level of each coverage level in the target cell. The random access parameter is notified to the UE; in the random access process with the target cell, the UE determines, according to the random access parameters of each coverage level in the target cell, a coverage level corresponding to the notified coverage level. matching access parameters, and using the determined access parameters to access the target cell. By adopting the present invention, the success rate of UE handover to the target cell can be improved.

Description

Method and system for inter-cell handover based on physical channel repeat transmission

technical field

The present invention relates to mobile communication technology, in particular to a method and system for inter-cell handover based on repeated transmission of physical channels.

Background technique

With the development of smart grid, the electricity information collection system has put forward new and higher requirements for communication channels. At present, the 230MHz frequency band is mainly used in digital radio stations to undertake remote data collection work. Due to the low rate provided, it can only be used for some simple communication applications, and cannot meet the growing business needs of smart grids and sensor networks.

TD-LTE230 power consumption information acquisition system is based on TD-LTE technology, combined with advanced technologies such as spectrum sensing, carrier aggregation, interference demodulation, software radio, etc., using discrete spectrum resources in the power industry in the 230MHz frequency band, innovative research and development, deep customization of wireless communication system. According to the in-depth customization of power business communication requirements, the public network TD-LTE technology system, communication protocol and networking structure are optimized to improve terminal capacity and real-time service.

The 223.025-235.000MHz frequency band is used for telemetry, remote control, data transmission and other services. This frequency band consists of multiple scattered 25k channels, and the adjacent frequencies have been assigned to other industries for use, and there is no wide continuous spectrum resource. . There are 40 authorized frequency points in total, distributed in discrete and unequal intervals.

As shown in Figure 1, a radio frame consists of five subframes with a length of 5ms, of which subframe 0 is a downlink subframe, subframes 2, 3, and 4 are uplink subframes; subframe 1 is a special subframe, including 3 domains, namely DwPTS, GP and UpPTS.

LTE230 increases the demodulation performance of each channel by repeated transmission. The base station distinguishes different coverage levels according to the demodulation performance, and each coverage level has different indications of the repetition times of each message in the random access process and the number of preamble codes. Each cell can be configured with at most 3 coverage levels. During random access, the UE selects its own coverage level according to the RSRP value of the cell and the RSRP threshold in the system information. The system information also includes the access parameters and repetition times of each coverage level. According to these parameters, the PRACH transmission period and Send offset.

Random access supports PRACH code division and time division. The details are as follows:

In the coverage level code division mode, each coverage level period is different, and each coverage level preamble code starts to be sent at the first two radio frame positions of each PRACH period.

Taking Figure 2 as an example, the number of preamble codes for three coverage levels indicates: {4, 2, 1}, the number of codes for coverage level 1 is 4, corresponding to codes 0 to 3; the number of codes for coverage level 2 is 2, corresponding to Codes 4 to 5; coverage level 3 code number is 1, corresponding to code 6. The UE randomly selects a preamble code in the corresponding preamble code range according to the selected coverage level. The non-contention resource is code 7. The PRACH cycles of 3 coverage levels are 2, 4, and 8 radio frames.

In the coverage level time division mode, each coverage level of the PRACH cycle is consistent, and the time windows for terminal access at different coverage levels are different.

Taking FIG. 3 as an example, the number of preamble codes for each coverage level is 7, corresponding to codes 0 to 6; the UE randomly selects a preamble code in the corresponding preamble code range according to the selected coverage level. A non-contending resource is code 7. The PRACH cycle is 14, and the transmission offset of the preamble codes of each coverage level is the 0th, 2nd, and 6th radio frames of each cycle.

Taking X2 handover as an example, the current X2 handover flowchart is shown in Figure 4 and includes:

Step 401, the UE sends an RRC measurement report to the source cell.

Step 402 , the source cell determines, according to the RRC measurement report, that an inter-cell handover needs to be performed for the UE, and sends a handover preparation message to the target cell.

Step 403: The target cell sends a handover response message to the source cell.

Step 404: The source cell sends a radio resource control (RRC) reconfiguration message (ie, a handover command) to the UE according to the handover response message.

Step 405: The UE sends a random access request message to the target cell according to the RRC reconfiguration message.

Step 406: The target cell sends a random access response message to the UE.

Step 407, the UE sends an RRC reconfiguration message complete message (ie, a handover complete message) to the target cell.

Step 408: The target cell notifies the source cell to release corresponding resources.

According to the existing handover technology, when the source cell and the target cell use the physical channel repeated transmission technology, the UE cannot obtain random access parameters of each coverage level in the target cell. In this way, during the process of accessing the target cell, the UE cannot select random access parameters such as coverage level, PRACH period, PRACH offset, and the number of repetitions of each message, so that the UE cannot use the appropriate random access parameters to access the system. It is not possible to use the physical channel for repeated transmission to improve the success rate of the UE handover to the target cell.

SUMMARY OF THE INVENTION

In view of this, the main purpose of the present invention is to provide an inter-cell handover method and system based on physical channel repeated transmission, which can improve the success rate of UE handover to a target cell.

In order to achieve the above object, the technical scheme proposed by the present invention is:

An inter-cell handover method based on repeated transmission of physical channels, comprising:

When the inter-cell handover of the user equipment UE needs to be performed, the source cell notifies the target cell of the RSRP measurement value of the reference signal received power of the UE to the target cell;

The target cell determines the coverage level of the UE in the target cell according to the RSRP measurement value, and notifies the UE of the coverage level and random access parameters of each coverage level in the target cell;

During the random access process with the target cell, the UE determines, according to the random access parameters of each coverage level in the target cell, access parameters that match the notified coverage level, and uses the determined access parameters. Access parameters to access the target cell.

Preferably, notifying the target cell of the RSRP measurement value of the UE on the target cell includes:

When receiving the measurement report from the UE, the source cell carries the RSRP measurement value of the UE to the target cell in a handover preparation message and sends it to the target cell.

Preferably, the determining the coverage level of the UE in the target cell includes:

The target cell determines the coverage level of the cell corresponding to the RSRP measurement value according to the RSRP threshold corresponding to each coverage level of the cell, and determines the coverage level as the coverage level of the UE in the target cell.

Preferably, the notification of the coverage level and the random access parameters of each coverage level in the target cell to the UE includes:

The target cell carries the coverage level of the UE in the target cell and the random access parameters of each coverage level in the target cell in a handover preparation response and sends it to the source cell;

The source cell carries the coverage level and random access parameters of each coverage level in the target cell in an RRC reconfiguration message and sends it to the UE.

Preferably, the inter-cell handover is X2 handover or S1 handover.

An inter-cell handover system based on repeated transmission of physical channels, comprising:

a source cell, configured to notify the target cell of the RSRP measurement value of the reference signal received power of the UE to the target cell when the inter-cell handover of the user equipment UE needs to be performed;

a target cell, configured to determine the coverage level of the UE in the target cell according to the RSRP measurement value, and notify the UE of the coverage level and random access parameters of each coverage level in the target cell;

The UE is configured to, in the random access process with the target cell, determine the access parameter matching the notified coverage level according to the random access parameters of each coverage level in the target cell, and use the determined access parameter access parameters to access the target cell.

Preferably, the source cell is configured to, when receiving the measurement report from the UE, carry the RSRP measurement value of the UE to the target cell in a handover preparation message and send it to the target cell.

Preferably, the target cell is used to determine the coverage level of the cell corresponding to the RSRP measurement value according to the RSRP threshold corresponding to each coverage level of the cell, and determine the coverage level as the UE in the target cell. coverage level.

Preferably, the target cell is used to carry the coverage level of the UE in the target cell and the random access parameters of each coverage level in the target cell in the handover preparation response and send it to the source cell;

The source cell is configured to carry the coverage level and random access parameters of each coverage level in the target cell in an RRC reconfiguration message and send it to the UE.

Preferably, the inter-cell handover is X2 handover or S1 handover.

To sum up, in the method and system for inter-cell handover based on physical channel repeated transmission proposed by the present invention, the source cell notifies the target cell of the RSRP measurement value of the UE to the target cell, and then the target cell measures the RSRP of the target cell according to the UE. value, determine the coverage level of the UE in the target cell, and then notify the UE of the coverage level and the random access parameters of each coverage level in the target cell. The coverage level of the target cell and the random access parameters of each coverage level in the target cell, and the access parameters that match the coverage level of the UE in the target cell are selected to access the target cell, so that the advantage of repeated transmission of the physical channel can be fully utilized. to improve the success rate of UE handover to the target cell.

Description of drawings

1 is a schematic diagram of a frame structure in the prior art 230;

Fig. 2 is a schematic diagram of code division sub-coverage level;

Fig. 3 is a schematic diagram of time division and coverage level;

4 is a schematic diagram of an existing X2 handover process;

5 is a schematic flowchart of a method according to an embodiment of the present invention;

FIG. 6 is a schematic flowchart of an embodiment of X2 handover according to the present invention;

FIG. 7 is a schematic diagram of a system structure according to an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

The core idea of the present invention is: in the handover process, the RSRP measurement value of the UE on the target cell is notified to the target cell, the target cell determines its coverage level in the cell, and the coverage level and each coverage level in the target cell are determined by the target cell. The random access parameters are notified to the UE. In this way, the UE can determine an appropriate access parameter according to the coverage level determined for it by the target cell and random access parameters of each coverage level in the target cell, and use the access parameter to access the target cell.

FIG. 5 is a schematic flowchart of a method according to an embodiment of the present invention. As shown in FIG. 5 , the method for inter-cell handover based on repeated transmission of physical channels implemented in this embodiment mainly includes:

Step 501: When the user equipment UE needs to perform inter-cell handover, the source cell notifies the target cell of the RSRP measurement value of the reference signal received power of the UE to the target cell.

Preferably, a handover preparation message may be used to notify the target cell of the RSRP measurement value of the UE on the target cell, specifically as follows:

When receiving the measurement report from the UE, the source cell carries the RSRP measurement value of the UE to the target cell in a handover preparation message and sends it to the target cell.

Specifically, the inter-cell handover may be X2 handover or S1 handover.

Step 502: The target cell determines the coverage level of the UE in the target cell according to the RSRP measurement value, and notifies the coverage level and random access parameters of each coverage level in the target cell to the target cell. UE.

The difference between this step and the existing solution is that the target cell needs to determine its coverage level in this cell for the UE according to the RSRP measurement value of the UE in the target cell, so that the UE can use the coverage level and the coverage level of each coverage level in the target cell. Random access parameters, select the appropriate access parameters to access the target cell, in order to improve the demodulation performance, so as to ensure the success rate and efficiency of cell handover.

Specifically, the following method can be used to determine the coverage level of the UE in the target cell:

The target cell determines the coverage level of the cell corresponding to the RSRP measurement value according to the RSRP threshold corresponding to each coverage level of the cell, and determines the coverage level as the coverage level of the UE in the target cell.

Preferably, in this step, a handover command may be used to notify the UE of the coverage level of the UE in the target cell and the random access parameters of each coverage level in the target cell, and the specific process method is as follows:

Step x1, the target cell sends the coverage level of the UE in the target cell and the random access parameters of each coverage level in the target cell in the handover preparation response to the source cell;

Step x2: The source cell sends the coverage level and random access parameters of each coverage level in the target cell in an RRC reconfiguration message to the UE.

Step 503: During the random access process with the target cell, the UE determines, according to the random access parameters of each coverage level in the target cell, an access parameter that matches the notified coverage level, and uses The determined access parameters access the target cell.

In this step, the UE will determine the access parameter matching the notified coverage level according to the coverage level of the target cell notified by the target cell and the random access parameters of each coverage level in the target cell. It is ensured that the access parameters selected by the UE match the actual channel conditions, thereby improving the efficiency and success rate of the UE handover to the target cell.

Specifically, according to the coverage level of the UE in the target cell and the random access parameters of each coverage level in the target cell, the method for determining the access parameter is known to those skilled in the art, and details are not repeated here.

The specific implementation of the present invention will be further described below by taking X2 handover as an example. FIG. 6 is a schematic flowchart of an embodiment of an X2 handover according to the present invention. As shown in Figure 6, the X2 handover process includes:

Step 601, the UE sends an RRC measurement report to the source cell;

Step 602: The source cell determines, according to the RRC measurement report, that an inter-cell handover needs to be performed for the UE, and sends a handover preparation message to the target cell.

The difference from the existing solution is that the handover preparation message will carry the RSRP measurement value of the UE for the target cell.

Step 603: The target cell determines the coverage level of the UE in the target cell according to the handover preparation message, and sends a handover response message to the source cell; the handover response message carries the index value of the coverage level of the UE in the target cell, and each element in the target cell. Random access parameters for the coverage level.

Step 604: The source cell sends an RRC reconfiguration message (that is, a handover command) to the UE according to the handover response message. The RRC reconfiguration message will carry the index value of the coverage level of the UE in the target cell, and each coverage in the target cell. Random access parameters for the level.

Step 605: The UE determines the appropriate access parameters (including the number of repetitions, the PRACH transmission cycle, the transmission offset, and the number of repetitions) according to the index value of the coverage level carried in the RRC reconfiguration message and the random access parameters of each coverage level in the target cell. etc.), according to these access parameters, send a random access request message to the target cell.

Step 606: The target cell determines its access parameters according to the coverage level of the UE in the cell, and sends a random access response message to the UE according to the determined access parameters.

Step 607: The UE sends an RRC reconfiguration message complete message (ie, a handover complete message) to the target cell according to the random access response message.

Step 608: The target cell notifies the source cell to release corresponding resources.

FIG. 7 is an inter-cell handover system based on repeated transmission of physical channels corresponding to the method embodiment shown in FIG. 5 . As shown in FIG. 7 , the system includes:

a source cell, configured to notify the target cell of the RSRP measurement value of the reference signal received power of the UE to the target cell when the inter-cell handover of the user equipment UE needs to be performed;

a target cell, configured to determine the coverage level of the UE in the target cell according to the RSRP measurement value, and notify the UE of the coverage level and random access parameters of each coverage level in the target cell;

The UE is configured to, in the random access process with the target cell, determine the access parameter matching the notified coverage level according to the random access parameters of each coverage level in the target cell, and use the determined access parameter access parameters to access the target cell.

Preferably, the source cell is configured to, when receiving the measurement report from the UE, carry the RSRP measurement value of the UE to the target cell in a handover preparation message and send it to the target cell.

Preferably, the target cell is used to determine the coverage level of the cell corresponding to the RSRP measurement value according to the RSRP threshold corresponding to each coverage level of the cell, and determine the coverage level as the UE in the target cell. coverage level.

Preferably, the target cell is used to carry the coverage level of the UE in the target cell and the random access parameters of each coverage level in the target cell in the handover preparation response and send it to the source cell;

The source cell is configured to carry the coverage level and random access parameters of each coverage level in the target cell in an RRC reconfiguration message and send it to the UE.

Preferably, the inter-cell handover is X2 handover or S1 handover.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. An inter-cell handover method based on repeated transmission of a physical channel, comprising:

when the inter-cell switching of User Equipment (UE) is needed, a source cell informs a target cell of a Reference Signal Received Power (RSRP) measured value of the UE to the target cell;

the target cell determines the coverage grade of the UE in the target cell according to the RSRP measurement value, and notifies the coverage grade and the random access parameters of each coverage grade in the target cell to the UE;

and in the random access process of the UE and the target cell, determining an access parameter matched with the notified coverage grade according to the random access parameter of each coverage grade in the target cell, and accessing the target cell by using the determined access parameter.

2. The method of claim 1, wherein notifying the target cell of the RSRP measurement of the target cell by the UE comprises:

and when receiving the measurement report of the UE, the source cell carries the RSRP measurement value of the UE to the target cell in a handover preparation message and sends the RSRP measurement value to the target cell.

3. The method of claim 1, wherein determining the coverage level of the UE at the target cell comprises:

and the target cell determines the coverage grade of the cell corresponding to the RSRP measurement value according to the RSRP threshold corresponding to each coverage grade of the cell, and determines the coverage grade as the coverage grade of the UE in the target cell.

4. The method of claim 1, wherein notifying the UE of the coverage level and the random access parameters of each coverage level in the target cell comprises:

the target cell carries the coverage grade of the UE in the target cell and the random access parameters of each coverage grade in the target cell in a handover preparation response and sends the parameters to the source cell;

and the source cell carries the coverage grade and the random access parameters of each coverage grade in the target cell in an RRC reconfiguration message and sends the RRC reconfiguration message to the UE.

5. The method of claim 1, wherein the inter-cell handover is an X2 handover or an S1 handover.

6. An inter-cell handover system based on repeated transmission of a physical channel, comprising:

the source cell is used for informing the target cell of the Reference Signal Received Power (RSRP) measured value of User Equipment (UE) to the target cell when the inter-cell switching of the UE is needed;

the target cell is used for determining the coverage grade of the UE in the target cell according to the RSRP measurement value and informing the UE of the coverage grade and the random access parameters of each coverage grade in the target cell;

and the UE is used for determining the access parameters matched with the notified coverage grade according to the random access parameters of each coverage grade in the target cell in the random access process with the target cell and accessing the target cell by using the determined access parameters.

7. The system of claim 6,

and the source cell is used for carrying the RSRP measurement value of the UE to the target cell in a handover preparation message and sending the RSRP measurement value to the target cell when the measurement report of the UE is received.

8. The system of claim 6,

and the target cell is configured to determine, according to an RSRP threshold corresponding to each coverage level of the cell, a coverage level of the cell corresponding to the RSRP measurement value, and determine the coverage level as the coverage level of the UE in the target cell.

9. The system of claim 6,

the target cell is used for sending the coverage grade of the UE in the target cell and the random access parameters of each coverage grade in the target cell to the source cell by carrying the random access parameters in a handover preparation response;

and the source cell is used for carrying the random access parameters of the coverage grades and all the coverage grades in the target cell in an RRC reconfiguration message and sending the RRC reconfiguration message to the UE.

10. The system of claim 6, wherein the inter-cell handover is an X2 handover or an S1 handover.

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