| 1. IntroductionTD-SCDMA, the third generation mobile communication standard that China puts forward and holds the independent intellectual property rights, is one of the three primary standards certificated by ITU. The present study and exploiture to TD-SCDMA is roughly limited relative to WCDMA and CDMA 2000. TD-SCDMA is put forward in China, both the international and domestic research to it is seriously lack, so its study must be inhanced further more to insure the success. In order to allocate resources to integrated service, which including voice service—real time service (RT) and data service—non-real time service(NRT), TD-SCDMA, one of the 3G standards, need to be able to afford an efficient resource-allocating mode . As one of the key technic of TD-SCDMA, Baton Handover(BH) is very important for TD-SCDMA system. Studying on the BH is good at the compatibility of TD-SCDMA system with others in the radio communication research field.Radio resource management (RRM) can use limited wireless resources rationally and effectively, which includes power control, handover, call admission control (CAC), congestion control and pocket control. BH of the TD-SCDMA system, which in order to ensure the continuity of UE, the load of network and operation maintenance, is a process making UE transform from current link layer to other cellular, and a technic that the communication service don't interrupt. Optimize of handover is very important for any cellular communication system. So based on intrinsic algorithms, not dropping data and interrupting communication, we can optimize them to save channel resource.After the study on the domestic and overseas'BH algorithmic, the strategy in the BH process of TD-SCDMA system has been studied and a mixed-data rate, new algorithm called resource reserved with call preferential queuing and resource reserved with auto suit limit call preferential queuing scheme are introduced in this paper. 2. Resource Reserved with Call Preferential Queuing SchemeConsidering system handover influence, if it can reduce the lost of handover, it can abate handover negative influence. And based on queue theory, we improve arithmetic in increasing user PRI. In this paper, we staple user into 4 types from low to high: common low rate user, common high rate user, VIP low rate user and VIP high rate user. And we set up a two-dimension Markov chain resource reserved model.In this model, there are N+M channel in the cellular: M channels will be used in handover requirement; N channels will be used in new call requirement in the cell and handover requirement in other cell. So new call requirement will be rejected when there are more than M (include M) channels used in the cell. But handover requirement will be accepted in other cell. However, handover requirement will be rejected when there are more than M+N (include M+N) channels used in other cell. Getting across analyzing this model, we get p (i , j), and3. Resource Reserved with Auto Suit Limit Call Preferential Queuing SchemeBased on the algorithm called resource reserved with call preferential queuing scheme, we divide requirement into two types: high rate user and low rate user. For the low rate user, the parameter isn't changed. But for the high rate user, channel performance drops quickly in its cell. We change the parameter with move rate. We make the parameter of high rate user drop properly and satisfy handover condition, and obtain the priority. So high rate user can be serviced firstly. The scheme reduces the channel block and improves the total channel utilization efficiency.4. The simulation and analysis of the scheme improved In this paper, we put forward a new algorithm of BH that is based on the method of tradition, resource reserved, FIFO, PRI queue and auto suit limit. Imposing the technique of synchronization of above and smart antenna, we estimate possible direction based on move direction. Also we make sure PRI of BH that is based on VIP sigh, pilot sigh, distance, move rate and direction, acceleration latency time etc.To validate the performance of the scheme improved, tradition, resource reserved, FIFO, PRI queue, the new method are simulated by computer respectively. From the simulation results, compared with the method of tradition, resource reserved, FIFO, PRI queue, the new method can improve the performance of handover, and this arithmetic will be used in the cells of high rate users. The result shows that, compared with common low rate user, common high rate user, VIP low rate user and VIP high rate user, the division of the users improves the total channel utilization efficiency and QoS of systems.5. ConclusionOn the base of studying on the domestic and overseas'BH algorithmic, the strategy in the BH process of TD-SCDMA system has been studied and a mixed-data rate, a new algorithm called resource reserved with auto suit limit call preferential queuing scheme is introduced in this paper. Especially in high move rate user, this method is better.And certain reference is provided for the research on the BH arithmetic of TD-SCDMA. |
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