The Research Of Forward Link Bandwidth Allocation Scheme In Radio Resource Management

Nowadays, 3G technologies have entered the period of commercial application at home and abroad. The optimal mode of the development of mobile broadband networks is integrating all kinds of 3G-enhanced technologies on the platform of 3G networks based on the CDMA technology. Improving QoS provisionings for radio data traffics is the main object of optimizing and updating the 3G networks.Radio resource management is one of the key technologies to exert the performance of radio netwoks and guarantee the QoS of mobile users. The forward link bandwidth allocation scheme connects the average resource utility ratio of system and the data rate of users directly, and the growth of radio data traffics requires the forward link bandwidth allocation scheme with better performance in 3G networks.This paper studies the forward link bandwidth allocation scheme in 3G technologies. The main research contents include the code allocation scheme in OVSF-CDMA systems and the forward packet scheduling scheme in the systems using TDM (Time Division Multiplex) technology in the forward link.In OVSF-CDMA systems, OVSF codes are the key technology to support variable rate traffics and the OVSF code allocation scheme affects the performance of system. 3GPP supports multi-code schemes. After the description for the rules of code allocation, 3GPP shows a rapid arithmetic which can be used to obtain the optimal allocation code work. This paper analyzes the limitation of this arithmetic and proposes a common rapid arithmetic used to get the optimal allocation code word. In order to elimate the code blockings in OVSF-CDMA system, reassignement is introduced into the process of code allocation. While improving the average resource utility ratio, reassignments bring extra computing burden and signaling overhead. To reduce the bad influences brought by reassignments, paper proposes a schem using the reassignment coefficient as the control threshold. Based on above research, this paper proposes an applied multi-code adaptive reassignment control (MARC) scheme. This scheme uses the threshold control arithmetic which can maintain the reassignment coefficient at a ceitain degree. By using the out loop control mechanism to adjust the value of threshold, systems can reduce the code blocking ratio and ease the bad affects to systems caused by reassignments. Simulation results show that MARC scheme has similar system performance like DCA but performs better than DCA scheme in the reassignment performances.In the systems using TDM technology such as HSDPA, 1xEV-DO,the bandwidth allocation is implemented by the forward packet scheduling scheme. The realization process of packet scheduling schemes in systems is affected by physical protocol, MAC protocol and other techniques. This paper studies the influence to the performance of scheduling scheme casued by techniques such as HARQ, PDMA and proposes a improved PFS orienting to support delay-sensitive traffics.The MARC scheme is applied in City Mobile Telecomunication system and the systems which derive from it, and this scheme improves the system capacity of the series of CMT products effectively.