TD-SCDMA系统中的上/下行链路动态信道分配策略

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.

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

In TD-SCDMA sy stem, symmetr ic v oice t raf fic exist s betw een uplink ( U L ) and dow nlink ( DL) , w hile data t raff ic being hig hly asymmet ric to data t raf fic. For the sake of adapt ing to data tr aff ic asymmet ry betw een U L and DL, an U L/ DL dynamic channel allocat ion ( DCA) str ategy w as proposed for TD-SCDMA system. In the slow DCA, t ime slot dynamically based on the number of ongo ing voice user s and the UL/ DL t raf fic rat io in nex t interv al w er e al located. According to the pr operty of the load v arying t imely in uplink and dow nlink, the predict ive metho d w as int roduced to predict the next interval tr aff ic load. In the fast DCA, the g uard channel method and the mo vable boundary metho d w ere combined. T he st rategies w ith and w ithout t raf fic predicted w ere simulated together w ith the tr aditional symmet ric t ime slo t al locat ion scheme. T he simulated resul ts show that the pr opo sed scheme based on t raff ic prediction can not only allocate UL/ DL time slot s acco rding to the asymmet ry U L/ DL t raf fic and pr ovide bet ter data service performance w ithout af fect ing the v oice service perfo rmance, but also use channels mo re eff iciently.