TD-SCDMA系统中的上/下行链路动态信道分配策略

Dynamic channel allocation strategy between uplink and downlink for TD-SCDMA system

在TD-SCDMA系统的上行和下行链路中,话音业务是对称的,而数据业务是非对称的。为了适合于这种业务的非对称,提出在TD-SCDMA系统中采用上/下行链路动态信道分配(DCA)的策略。在慢DCA中,根据在线话音用户数和下一时隙上/下行链路中业务数量的比值来动态地分配时隙。针对上/下行链路中的负载具有时变性的特点,提出对下一时隙业务负载进行预测的方法。在快DCA中,提出将保护信道方法和可移动边界方法相结合的策略。同时,将这两种方法与传统的对称时隙分配方法进行仿真比较。仿真结果表明,基于业务预测的方法,能够根据非对称的上/下行链路业务对上/下行链路中的时隙进行动态分配;在不影响话音业务性能的情况下,该方法不仅具有更好的数据业务性能,而且能更有效地使用信道。

In TD-SCDMA system, symmetric voice traffic exists between uplink （UL） and downlink （DL）, while data traffic being highly asymmetric to data traffic. For the sake of adapting to data traffic asymmetry between UL and DL, an UL/DL dynamic channel allocation （DCA） strategy was proposed for TD-SCDMA system. In the slow DCA, time slot dynamically based on the number of ongoing voice users and the UL/DL traffic ratio in next interval were allocated. According to the property of the load varying timely in uplink and downlink, the predictive method was introduced to predict the next interval traffic load. In the fast DCA, the guard channel method and the movable boundary method were combined. The strategies with and without traffic predicted were simulated together with the traditional symmetric time slot allocation scheme. The simulated results show that the proposed scheme based on traffic prediction can not only allocate UL/DL time slots according to the asymmetry UL/DL traffic and provide better data service performance without affecting the voice service performance, but also use channels more efficiently.