CN1194489C - Method for user equipment to select primary cell in mobile communication system - Google Patents

Abstract

The present invention provides a method for a user equipment to select a primary cell in a mobile communication system. The method includes: first, the user equipment periodically measures the pilot information signal-to-interference ratio of the dedicated physical control channel of each cell in the active set, and the signal-to-interference ratio can reflect the dedicated The power of the signal transmitted by the channel, the degree of interference of the channel, and the size of the noise; then, according to the set situation, determine the cell where the dedicated channel with the best signal-to-interference ratio is located; and set this cell as the primary cell of the user equipment. In the present invention, the UE can select a cell with the best communication effect in the active set as its primary cell, which ensures the communication quality in the communication system and overcomes many problems existing in the method of selecting the primary cell by measuring RSCP in the prior art . Moreover, the present invention can perform cell selection according to the SIR calculated by the UE, so that the present invention can be implemented without increasing system overhead.

Description

Method for user equipment to select primary cell in mobile communication system

technical field

The invention relates to the technical field of mobile communication, in particular to a method for user equipment to select a primary cell in a mobile communication system.

Background technique

At present, in the WCDMA (Wideband CDMA: Broadband CDMA) mobile communication system, the SSDT (Site Selection Transmit Diversity: Base Station Selection Transmit Diversity) method is used to select a cell from the active set and set it as the primary cell of the UE (User Equipment: User Equipment) , while the other cells in the active set are non-primary cells, the primary cell is responsible for transmitting service data, while the non-primary cell does not transmit service data, so as to reduce the interference to other users caused by multi-cell transmission, and the existence of non-primary cells guarantees The UE can quickly select the base station without the participation of the network; the active set is a set of multiple cells that keep in touch with the UE at the same time, and the UE can simultaneously receive the P-CPICH (Priamary Common Pilot Channel) of each cell in the active set : Primary Common Pilot Channel) information.

Moreover, in the prior art, the UE selects the primary cell by periodically measuring the RSCP (Received Signal Code Power: Received Signal Code Power) of the P-CPICH, and according to the measurement results, it is determined that the cell with the highest RSCP is the cell of the UE. main cell.

It can be seen from the above prior art that although P-CPICH is a continuous pilot channel and can reflect channel conditions in a continuous period of time, P-CPICH is a common channel that provides reference for other channels after all, and cannot accurately reflect dedicated channels. The condition of the channel. Moreover, the RSCP measured by the UE can only reflect the power of the signal, but cannot reflect the interference and noise of the channel. That is, the RSCP does not provide measurement parameters based on the interference degree of the channel and the magnitude of the noise, so it cannot fully reflect the status of the channel. For example, when the UE selects a primary cell, it selects a cell with the largest RSCP in its active set as its primary cell, but there are currently many users in this cell, and the interference and noise are relatively large, so this cell is used as the primary cell. Not the best option for UE. In addition, the CDMA (Code Division Multiple Access) mobile communication system is an interference-limited system, and the amount of interference determines the number of users accommodated in a cell and the quality of services provided. Therefore, selecting the primary cell of the UE without considering channel interference and noise conditions cannot ensure that the UE selects a cell with the best communication conditions as its primary cell.

Contents of the invention

The present invention provides a method for user equipment to select a primary cell in a mobile communication system, so as to ensure that a UE in the mobile communication system can select a cell with the best communication status as its primary cell.

The purpose of the present invention is achieved in this way: the method for user equipment to select a primary cell in a mobile communication system includes:

(1) For the pilot information of the dedicated physical control channel of each cell in the active set, the user equipment periodically calculates the signal-to-interference ratio value of each time slot in each physical frame, and calculates the signal-to-interference ratio of the 14 time slots in the physical frame After the ratios are accumulated and summed, they are used as the signal-to-interference ratio of the cell. The signal-to-interference ratio reflects the power of the signal transmitted by the dedicated channel, the degree of interference of the channel, and the size of the noise;

(2) Determine the cell where the dedicated physical control channel with the best signal-to-interference ratio is located, that is, determine the cell where the dedicated channel with the best communication effect is located;

(3) The cell is set as the primary cell of the user equipment, and other cells are set as non-primary cells of the user equipment.

The dedicated physical control channel is a dedicated physical control channel in a WCDMA (Wideband Code Division Multiple Access) mobile communication system.

Described step (3) comprises:

(31) Setting a threshold value based on the signal-to-interference ratio according to the communication needs of the user equipment;

(32) comparing the signal-to-interference ratio value of each dedicated physical control channel with the threshold value;

(33) The cell where the dedicated physical control channel that meets the threshold requirement is located is the cell with the best signal-to-interference ratio.

It can be seen from the above-mentioned technical solution provided by the present invention that the present invention selects the primary cell of the UE by measuring the signal-to-interference ratio of the pilot information of the dedicated channel. The signal-to-interference ratio of the pilot information comprehensively reflects the power of the signal, the channel Therefore, the pilot information of the dedicated channel can accurately reflect the status of the dedicated channel used by the UE in the actual communication process. Therefore, in the present invention, the UE can select a channel with the best communication effect in the active set. The cell acts as its own primary cell, thereby ensuring the communication quality in the communication system, and overcoming many problems existing in the method of selecting the primary cell by measuring RSCP in the prior art. In addition, in the WCDMA system, the UE needs to calculate the signal-to-interference ratio in each time slot to regulate the downlink transmission power of the base station. The present invention can perform cell selection according to the signal-to-interference ratio calculated by the UE. The invention is implemented without adding overhead to the system.

Description of drawings

Fig. 1 is the specific embodiment flow chart of the present invention.

Detailed ways

The method of using SSDT in the prior art is to select the cell with the highest transmit signal power in the active set as the main cell to transmit service data, and at the same time restrict other cells in the active set to transmit service data information, thereby reducing interference to other users in the cell. However, if the UE only considers the signal power when selecting a cell, and does not consider channel interference and noise, it may select a cell with high signal power, interference, and noise as the primary cell, which will not help reduce downlink transmit power. Just aiming at this problem, the present invention improves the method for the UE to select the primary cell.

The method for user equipment to select a primary cell in a mobile communication system provided by the present invention is especially applicable to a WCDMA mobile communication system, and specific implementation methods are described as follows in conjunction with the accompanying drawings:

Step 1: The UE periodically measures the SIR (Signal-to-Interference Ratio: Signal-to-Interference Ratio) value of the pilot of the DPCCH (Dedicated Physical Control Channel: Dedicated Physical Control Channel) of each cell in the active set. The SIR reflects the value transmitted by the Dedicated Physical Control Channel. Signal power, channel interference and noise;

Calculate the SIR value of each time slot in each physical frame, and accumulate and sum the SIR values of the 14 time slots in the physical frame; SIR uses the pilot information of the dedicated physical control channel, which can reflect the status of the dedicated channel , and in current WCDMA technical standards, the dedicated channels of the primary cell and the non-primary cell all transmit DPCCH information in the SSDT process, which provides a basis for the implementation of the present invention;

In addition, because in the WCDMA system, the UE needs to calculate the SIR value for each time slot to control the downlink transmission power, so the present invention will not increase the overhead of the system, and will not affect the existing system;

Step 2: Set a threshold value based on the SIR value according to the communication needs of the user equipment;

Step 3: compare the pilot information SIR value of each dedicated physical control channel in step 1 with the threshold value, and judge whether each SIR value meets the threshold value requirement, if so, perform step 4, otherwise, perform step 5;

Step 4: The cell where the dedicated physical control channel that meets the threshold value requirement is located is the cell with the best signal-to-interference ratio, and this cell is set as the primary cell of the user equipment;

Step 5: Set the cell as a non-primary cell of the user equipment.

Through the above process, the UE can select a cell with the best communication effect in the active set as its primary cell, and use other cells as non-primary cells.

In the specific embodiment of the present invention, it is also possible to directly compare the signal-to-interference ratio of each cell in the active set, select the cell with the largest signal-to-interference ratio as the cell with the best communication effect, set it as the primary cell of the user equipment, and set the other cells as Set as the non-primary cell of the user equipment.

Claims (3)

1. A method for user equipment to select a primary cell in a mobile communication system, comprising: (1) For the pilot information of the dedicated physical control channel of each cell in the active set, the user equipment periodically calculates the signal-to-interference ratio value of each time slot in each physical frame, and calculates the signal-to-interference ratio value of the 14 time slots in the physical frame After the accumulation and summation, it is used as the signal-to-interference ratio of the cell. The signal-to-interference ratio reflects the power of the signal transmitted by the dedicated channel, the degree of interference of the channel, and the size of the noise; (2) Determine the cell where the dedicated physical control channel with the best signal-to-interference ratio is located, that is, determine the cell where the dedicated channel with the best communication effect is located; (3) The cell is set as the primary cell of the user equipment, and other cells are set as non-primary cells of the user equipment. 2. The method for user equipment to select a primary cell in a mobile communication system according to claim 1, wherein the dedicated physical control channel is a dedicated physical control channel in a wideband code division multiple access mobile communication system. 3. The method for user equipment to select a primary cell in a mobile communication system according to claim 1 or 2, characterized in that said step (3) includes: (31) Setting a threshold value based on the signal-to-interference ratio according to the communication needs of the user equipment; (32) comparing the signal-to-interference ratio value of each dedicated physical control channel with the threshold value; (33) The cell where the dedicated physical control channel that meets the threshold requirement is located is the cell with the best signal-to-interference ratio.

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