Medium access control for Beyond Third Generation heterogeneous wireless networks

• Main Author: Fong, Mo-Han
• Other Authors: Gulliver, T. Aaron
• Language: English; en
• Published: 2010
• Subjects: wireless communication systems; UVic Subject Index::Sciences and Engineering::Engineering
• Online Access: http://hdl.handle.net/1828/2208

This thesis focuses on one of the key development areas of Beyond IMT-2000 or Beyond 3rd Generation (B3G) systems recommended by ITU-R M.1645, that is, new radio access systems that provide significantly higher performance for different deployment scenarios which may encompass different access technologies while maintaining seamless access and mobility from the user's perspective. Our objective is to develop various Medium Access Control (MAC) solutions for this new B3G access system. We introduce a novel B3G multi-mode access system framework based on heterogeneous physical layer (PL) modes or configurations, anchored by a common layer 2 and layer 3 protocol stack. Such a system can support a wide variety of physical layer multiple access technologies to target different deployment scenarios and performance targets. The anchor or common layer 2/3 protocols enable seamless handoff and dynamic radio resource/load/spectrum management across the different PL modes to achieve optimum spectrum efficiency and Quality of Service (QoS) support. As a basic form of the proposed B3G multi-mode access system and the first evolution step from the existing 3rd Generation (3G) cellular systems, we propose the multi-carrier expansion of Direct Spread Code Division Multiple Access, i.e. MC DS-CDMA. MC DS-CDMA supports concurrent transmissions on multiple DS-CDMA carriers anchored by a common layer 2/3 protocol stack. The common layer 2/3 protocol stack supports fully asymmetrical and dynamic Forward Link (FL) and Reverse Link (RL) carrier(s) allocation based on QoS requirements and Service Level Agreement (SLA). MC DS¬CDMA also provides backward compatibility to existing single carrier DS-CDMA systems, thus allowing for overlay of legacy and new systems while the network deployment migrates towards B3G broadband support. We further investigate load balancing schemes across multiple PL modes sharing the same spectrum resource in Time Division Multiplex (TDM), Frequency Division Multiplex (FDM) or Code Division Multiplex (CDM) fashions. For TDM and FDM cases, we propose a new Integrated Load Balancing and Scheduling (ILBS) scheme that maximizes the system capacity while meeting users' QoS and SLA. For the CDM case, we propose a dynamic Walsh code and Base Station (BS) transmit power sharing scheme between power-controlled dedicated traffic channels and rate-controlled packet data channels across multiple CDMA carriers. An important aspect of MAC for wireless mobile systems is the MAC states management. We develop a universal MAC state machine concept that anchors the heterogeneous PL modes so that when a user switches from one PL mode to another, the MAC state and the associated context information of the MS can be retained. to minimize packet loss and PL mode switching/handoff latency. We further look into the decision criteria used to transition a user from one MAC state to another. It is an important part of MAC for both the existing 3G systems and the B3G systems. The decision criteria should aim to maximize system capacity while meeting users' QoS and SLA requirements, while at the same time achieving power-saving. We propose a novel priority based state transition algorithm that achieves these objectives. Overall, our research provides key solutions to the challenges of next generation wireless systems envisioned to encompass heterogeneous characteristics and performance targets.