标题: | GPRS之两段式上传频道分配 Two-Stage Dynamic Uplink Channel Assignment for GPRS (General Packet Radio Service) |
作者: | 江美燕 Chiang, Mei-Yan 林盈达 Lin, Ying-Dar 资讯科学与工程研究所 |
关键字: | GPRS;上传频道;频道分配;GPRS;uplink;channel assignment |
公开日期: | 1999 |
摘要: | 为了支援不同网际网路应用所需的服务品质,GPRS支援多频道分配;此外,为了使上传频宽能更有效率的运用,GPRS将多个使用者分配至同一频道,并依据各使用者当时的资料流量决定要上传频道分配给这些使用者中的哪一个使用。 如此将多频道分配给一个使用者,加上将多个使用者分配至同一频道再动态选取使用者来使用频道的动作,可被视为一个两段式上传频道分配的机制。在第一阶段,基地台依据由手机收到的上传要求讯息内容,决定分配多少个频道、哪些频道给此手机;在第二阶段,基地台针对每个上传频道,动态地在其中挑选出被分配至此频道中多个使用者之一来使用此频道。针对这个两段式分配机制,针对第一阶段,我们提出了两种维持各个PDCH间流量负担平衡的衡量标准;针对第二阶段,我们提出了一些预测的方式,来挑选使用者,以期增加上传频宽的使用率。 从模拟结果,我们可以发现,依据由实际传送情况测量到的流量作为频道负荷标准,比起单用每个频道所分配到的使用者个数为负荷标准,更加能维持频道间的负担平衡,且我们亦发现,若频道间的负担不平衡,将使所有频道整体的使用率降低;而第二阶段的预测方法中,我们发现RRLAA表现最佳,亦即猜错率最低,且我们也发现,预测错误的主要影响包括较长的封包排队时间和较低的整体频道使用率。 GPRS (General Packet Radio Service) supports multislot assignment for one user and multiplexing of several users in one PDCH (Packet Data CHannel). In this way, desired QoS (Quality of Services) are met by dynamically adjusting the allocation of traffic channels according to the instantaneous user bit rate. Such dynamic allocation procedure can be viewed as a two-stage assignment. On stage 1, BS (Base Station) assigns several PDCHs to one user. On stage 2, BS selects one of the multiplexed users in a PDCH to use the radio resource. In this paper, we examine how to maintain load balancing between PDCHs on stage 1 and propose several selection schemes on stage 2. From simulation results, it is observed that the penalty deduced by poor load balancing scheme is lower system throughput and negligible packet queueing delay. Among different stage2 selection policies, RRLAA (Round-Robin with Linearly-Accumulated Adjustment) outperforms while having the minimal mis-selection rate. The major penalty of mis-selection is observed to be higher packet queueing delay and lower system throughput. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#NT880394072 http://hdl.handle.net/11536/65572 |
显示于类别: | Thesis |