CN1210901C - Resource allocation method on switching for CDMa base station system - Google Patents

Abstract

The invention discloses a resource allocation method for CDMA base station system switching. Firstly, it is judged whether an adjacent cell with the same frequency and the same frame offset can be found in the same BTS. Whether the frame offset is the same as the currently used frame offset, if they are the same, perform soft handoff; if the conditions of soft handover cannot be met, use semi-soft handover. The invention can effectively avoid call drop, improve call effect and make full use of system resources.

Description

Resource Allocation Method During CDMA Base Station System Handover

The present invention relates to a CDMA base station system, in particular to a resource allocation method for handover between cells in the CDMA base station system.

Because the CDMA mobile communication system is far superior to other cellular systems in terms of system capacity and radiation reduction, the CDMA system has been more and more widely used all over the world. In the CDMA system, the handover of the mobile station in the CDMA base station system is a very important part, and different handover modes are adopted, which directly affect the handover success rate and resource utilization rate. When the mobile station is handed over in the CDMA base station system, it is necessary to specify the handover method and allocate various resources accordingly. The current handover methods mainly include soft handover, softer handover and semi-soft handover. The softer handover transmits and receives signals in the same base station It only needs to reassign the traffic channel and determine which channel unit in the channel unit that has established a call to use. During softer handover, because no new channel unit is allocated, the handover The process is short, and the possibility of call drop during switching is very low, so when switching, first judge whether a softer switching can be performed. Soft handover refers to the handover between the same carrier frequency in different cells. Soft handover needs to allocate channel units and service channels, and the frame offset must be the same as that of the original established call. The soft handover method is a major feature of the CDMA system. , using the soft handoff method, the call is not interrupted, so that the user can always keep the call even when moving fast. Semi-soft handover is a way of hard handover, which refers to the handover between different cells in the same base station controller (BSC, Base Station Controller). New service channels and channel units need to be allocated. The base station has established a call, and then establishes a call process with a new base station. Obviously, semi-soft handover is not an appropriate handover method that users want. This method directly affects the call drop rate and call effect during handover. In the current practical application, when the mobile phone finds that the pilot signal of the original base station is very weak and requires switching, it generally adopts arbitrarily selecting the switching method, resulting in a very low switching success rate, increasing the possibility of dropped calls during switching, and In many cases, it will cause a waste of system resources. Can not reflect the gapless call advantage of the CDMA system.

The purpose of the present invention proposes a resource allocation method when effectively avoiding call drop, improving call effect and making full use of system resources when switching over CDMA base station systems, so as to overcome the call drop rate caused by the arbitrariness of resource allocation during existing CDMA base station system switching High, low call quality and insufficient utilization of system resources.

In order to achieve the above object, the present invention proposes a resource allocation method when a CDMA base station system is switched, which is characterized in that, comprising the following steps:

101 judge whether the adjacent cell is in the base station controller according to the pilot frequency offset, if the adjacent cell is in the base station controller, continue, otherwise report that the handover cannot be performed, and turn to 116;

102 Judging whether the adjacent cell has a carrier frequency of the same frequency, if there is a carrier frequency of the same frequency, continue, otherwise turn to 111;

103 judging whether the current frequency has an idle traffic channel, if there is an idle traffic channel under the current frequency, then continue, otherwise turn to 111;

104 find the corresponding baseband data subsystem;

105. According to resource usage, judge whether softer handover is possible, if the conditions for softer handover are met, turn to 110, otherwise continue;

106 Obtain all available frame offsets according to the recorded frame offset usage;

107 Determine whether the available frame offset of the channel unit is the same as the currently used frame offset, if they are the same, perform soft handover, then continue, otherwise go to 111;

108 Judging whether there are idle and available channel unit resources, if there is no available channel unit resource, then turn to 111; otherwise continue;

109 Allocate channel element resources according to the allocated frame offset;

110 allocates idle traffic channels, if the handover resource allocation is completed, go to step 116; otherwise go to step 101;

111 According to the principle of load sharing, select the carrier frequency with the smallest load from all the carrier frequencies in turn, if there are still available carrier frequencies, continue, otherwise report resource allocation failure, go to 116;

112 select another carrier frequency, and perform semi-soft switching without allocating a new vocoder unit;

113 Judging whether there is an idle traffic channel under the carrier frequency, if there is no available idle traffic channel, then turn to 111; otherwise continue;

114 Determine whether the difference between the available frame offset of the channel unit and the start sampling time of each frame of the selector vocoder is smaller than the given maximum allowable frame offset of the channel unit and the start sampling time of each frame of the selector vocoder Poor, if less than, continue, otherwise resource allocation fails, go to 116;

115 Judging whether the cell still has idle channel unit resources, if so, turn to 109, otherwise turn to 111;

116 over.

By adopting the method of the present invention, the best switching mode can be selected according to the existing conditions. Under different conditions, modes such as softer switching, soft switching and semi-soft switching can be selected, thereby effectively improving the switching speed and reducing The selector vocoder and channel unit occupied by the call are eliminated, the resources are fully utilized, the capacity of the base station is expanded, and the economic benefit is improved. And it increases the success probability of soft handover, and reduces the call drop rate of the mobile station when handover. Compared with the existing switching method, many disadvantages caused by the randomness of the switching mode can be effectively avoided, and it is possible to maximize the efficiency of the switching process.

The present invention will be further described below in conjunction with accompanying drawing:

Fig. 1 is a flowchart of CDMA base station system handover resource allocation in the present invention.

In the flowchart shown in FIG. 1 , it is stipulated how many identical frame offsets are allowed on one channel board at most, and the frame offset of each channel unit is not fixed. According to the handover resource allocation strategy proposed by the present invention, first judge whether the mobile phone can be made softer handover, because its reliability is the highest; secondly, judge whether the soft handover condition is satisfied; if the soft handover condition cannot be satisfied, then select semi-soft handover . To reduce the occupied selector vocoder and channel unit, and reduce the drop rate. Since the CDMA system uses the pilot frequency offset to distinguish different base stations, it is first necessary to judge whether the adjacent cell is in the base station controller BSC according to the pilot frequency offset. If the adjacent cell is not in the base station controller BSC, report that handover cannot be performed , otherwise judge whether the adjacent cell has the same carrier frequency, if it has the same carrier frequency, judge whether the current frequency has an idle traffic channel, if there is an idle traffic channel under the current frequency, find the corresponding baseband data subsystem (BDS Base band DigitalSubsystem), according to the resource usage, determine whether a softer switch can be made. If the conditions for softer handover are met, resources are allocated, and the condition for softer handover is to find adjacent cells with the same frequency and the same frame offset in the same base transceiver station (BTS, basetransceiver station). Otherwise, it is judged whether soft handover can be performed, and if the available frame offset of the channel unit is the same as the currently used frame offset, soft handover is performed and resources are allocated. When the conditions of soft handover and softer handover are not satisfied, semi-soft handover is attempted, and the carrier frequency with the least load is selected according to the load sharing principle. If the carrier frequency has an idle traffic channel, and the available frame offset and selection of channel units If the difference between the start sampling times of each frame of the vocoder is less than a given value, resources are allocated for semi-soft switching. Otherwise return allocation failed. Therefore, the probability of soft handover is effectively increased, the drop rate during the call is reduced, and the occupancy of the selector vocoder and channel unit is minimized, resources are fully utilized, and economic benefits are improved.

Claims (3)

1. A resource allocation method when a CDMA base station system is switched, characterized in that, comprising the following steps: Step 1 (101) judges whether adjacent cell is in this base station controller according to pilot frequency offset, if this adjacent cell is in this base station controller, continues, otherwise report can not switch, turn step 16 (116); Step 2 (102) judges whether adjacent cell has the carrier frequency of same frequency, if there is the carrier frequency of same frequency, then continue, otherwise turn step 11 (111); Step 3 (103) judges whether current frequency has idle traffic channel, if there is idle traffic channel under current frequency, then continue, otherwise turn step 11 (111); Step 4 (104) finds the corresponding baseband data subsystem; Step 5 (105) judges whether softer handover is possible according to the resource usage situation, if the conditions for softer handover are met, then turn to step 10 (110), otherwise continue; Step 6 (106) Obtain all available frame offsets according to the recorded frame offset usage; Step 7 (107) judges whether to meet the soft handover condition, if met, then carry out soft handover, continue, otherwise turn to step 11 (111); Step 8 (108) judges whether there is idle and available channel element resource, if there is no available channel element resource, then turn to step 11 (111), otherwise continue; Step 9 (109) allocates channel element resources according to the allocated frame offset; Step 10 (110) allocates an idle traffic channel, handover resource allocation is completed, and turns to step 16 (116), otherwise turns to step 1 (101); Step 11 (111) selects the carrier frequency with the smallest load from all carrier frequencies in turn according to the load sharing principle, if there is still an available carrier frequency, then continue, otherwise report resource allocation failure, go to step 16; Step 12 (112) selects another carrier frequency, carries out the semi-soft switching that does not distribute new vocoder unit; Step 13 (113) judges whether there is an idle traffic channel under the carrier frequency, if there is no available idle traffic channel, then turn (111); if there is, then continue; Step 14 (114) judges whether the difference between the available frame offset of the channel unit and the start sampling time of each frame of the selector vocoder is less than the given maximum allowable frame offset of the channel unit and each frame of the selector vocoder Start the difference of sampling time, if less than, then continue, otherwise resource allocation fails, go to step 16 (116); Step 15 (115) judges whether this sub-district also has idle channel unit resources, if yes, turn to step 9 (109), otherwise turn to step 11 (111); Step 16 (116) ends. 2. The resource allocation method during CDMA base station system handover according to claim 1, characterized in that the softer handover condition described in step 5 (105) is that the same base station transceiver can find the same frequency and can be divided. Neighboring cells with the same frame offset. 3. The resource allocation method during CDMA base station system handover according to claim 1, wherein the soft handover condition in step 7 (107) is that the available frame offset of the channel unit is the same as the currently used frame offset .

Images