【作者】 蒋体钢；

【导师】 范平志；

【作者基本信息】 西南交通大学 ， 交通信息工程与控制， 2005， 博士

【摘要】 移动通信业务的飞速发展,使得频谱资源和用户需求间的矛盾越来越突出。随着数据通信业务需求的日趋增大,数据通信和话音通信之间也开始相互竞争有限的频率资源。研究表明,采用多层蜂窝系统(HCS),使得宏蜂窝覆盖低话务量地区并为快速呼叫提供服务,而微蜂窝覆盖高话务量地区并为慢速呼叫提供服务,则可以既保证较高的频谱利用效率,又能有效地降低呼叫的切换次数。而采用包分裂策略,可以在保证一定数据通信质量前提下,使话音通信质量不至于恶化。为此,本文围绕多层蜂窝系统无线信道资源管理中三个方面的问题展开了深入地研究:① 多层蜂窝系统话音呼叫信道分配策略,包括多层蜂窝系统话音双向溢出呼叫分析设计,多层蜂窝系统呼叫分层速度门限设计,多层蜂窝系统信道紧凑与借用策略分析设计;② GSM/GPRS信道分配策略,包括话音/数据DRA策略的一般分析模型分析,GSM/GPRS信道分配策略比较分析,带释放信道重组的包分裂策略分析设计,为新到达包分配分裂信道的分析设计,多业务多优先级分析设计;③ 多级蜂窝系统中允许话音和数据呼叫同时共用宏/微蜂窝信道分析设计等。 本文的主要研究工作与贡献表现如下: 1.通过对现有宏/微二层蜂窝模型进行深入分析,提出了任意N层蜂窝系统双向溢出呼叫模型,并进行了一般性理论分析,详细研究了各层在多级蜂窝系统中由于呼叫溢出而导致的性能影响。 2.通过对宏/微蜂窝系统速度门限的分析,提出了基于用户接入不满意度的速度门限。论文首先定义蜂窝系统的不满意度为宏蜂窝层接入不满意度和微蜂窝层接入不满意度的函数。基于此接入不满意度的速度门限可以在一定呼叫到达率,一定蜂窝网络信道分配情况下使用户接入满意度达到最大。 3.现有多层蜂窝系统话音信道分配策略通常仅仅考虑层间呼叫溢出,而不考虑单层蜂窝系统常用的信道借用。本文提出了同时考虑层内紧凑模式信道借用和层间信道溢出的思想。研究结果表明,在考虑层间呼叫溢出时如果同时考虑层内信道借用非常有效,其呼叫阻塞率比在仅考虑层间信道溢出的FCA策略下大为减少。更多还原

【Abstract】 As the mobile communication services grow rapidly, the conflict between frequency resources and subscriber’s demand is getting more seriously. With the increasing demand of data communications, data calls and voice calls start competing the limited channel resources. Recent research indicates that Hierarchical Cellular System (HCS) can increase the channel utilization and reduce the handoff rate effectively. For the data packet transmission, by using the packet De-Allocation scheme, the data service can be enhanced without degrading noticeably the voice service. Therefore, this thesis will focus on the following three key issues related to channel allocations in HCS, i.e. (1) channel allocation scheme for voice calls in HCS, which includes call bi-directional overflow strategy for HCS with arbitrary layers, new layer selection velocity threshold determination scheme for HCS, call bi-directional overflow scheme with channel borrowing in each layer of HCS; (2) channel allocation scheme for GSM/GPRS network, including general analysis model of dynamical channel allocation scheme for voice/data services in GSM/GPRS, performance analysis and comparison of several channel De-Allocation schemes, channel De-Allocation scheme with released channel reallocation, channel De-Allocation with released channel reallocation for both voice calls and packets calls, a new approximate analysis method for multiple traffic and multiple priorities in communication systems; (3) analysis and design of micro/macro channel allocation schemes allowing the sharing of both voice calls and data calls in HCS.The main research work and contributions of the thesis include the following aspects:1. Based on the analysis of the existing channel allocation schemes in macro/micro cellular system, an analytical model for channel allocation scheme with call bi-directional overflow in an HCS with arbitrary layers is proposed, together with the general theoretical analysis and performance evaluation due to the overflow in different layers.2. By analyzing the velocity threshold of layer selection in HCS, a new velocity threshold based on the service unsatisfaction is proposed. Through the velocity threshold, it is possible to achieve the maximum service satisfaction which is a function of the macro/micro service unsatisfaction, under certain call arrival rate and appropriate channel allocation.3. Of those existing channel allocation schemes in HCS, an important fact is that only the call overflowing strategy is considered, and no channel borrowing is investigated, as is the case in the single layer system. In this thesis, a new channel allocation scheme for HCS by considering both call bi-directional overflowing and channel borrowing is presented. Our results show that the blocking probability of the new scheme is much smaller than that of the FCA scheme with only call bi-directional overflowing.4. Different from the existing dynamical resource allocation (DRA) schemes in GSM/GPRS network which normally uses specific fixed parameters, this thesis proposes a general analysis model for DRA in GSM/GPRS networks, and a new strategy named DMCDRA which can dynamically adjust the minimum number of channels a packet can occupy. Our results show that, under different packets call arrival rate, the performance can be enhanced by changing the minimum number of channels a packet call can occupy.5. Based on the investigation of selecting the De-Allocation candidate and suitable time in GSM/GPRS network, this thesis proposes a few De-Allocation schemes for selecting candidate, i.e. selecting from the richest packet, from the poorest packet, from the oldest packet, from the young packet, and from the random packet. In addition, two strategies, i.e. priority De-Allocation and De-Allocation on demand, are discussed, together with the combination of how and when to select candidates. Simulation results show that the selection of De-Allocation candidate randomly with De-Allocation on demand is better because of its low complexity and better performances.6. Concerning the released channels which are not re-allocated immediately in the existing De-Allocation scheme in GSM/GPRS, this thesis proposes a new channel allocation scheme named DA_DRA_MCP which can re-allocate the released channels to packets calls promptly. Simulation results show that the更多还原