QoS-Enabled Power Efficient Next-Generation Broadband Wireless Access Systems

越来越多的人要求未来的网络应该是无所不在、无处不在、具有多媒体功能的，即任何人都应该随时随地拥有宽带接入。这就要求未来的网络接入应该是宽带、高速的，并支持各种多媒体应用的服务质量(Qos)。鉴于目前的接入技术(如WiFi、GSM/GPRS/3G UMTS和DSL电缆接入)不能充分满足上述要求，如果没有下一代支持服务质量的宽带无线接入技术的开发，这一愿景将不会实现。正交频分多址(OFDMA)技术已经成为下一代宽带无线接入网络中最有前途的传输技术候选。与传统的单载波系统相比，正交多载波传输方案具有更强的稳健性以缓解无线多径失真效应，并且可以根据用户的特定服务质量要求灵活地将可用子载波的任何子集分配给任何用户。该方案旨在为基于OFDMA的新兴宽带无线接入系统探索有效的无线和发射功率资源管理方案，以保证用户所感知的服务质量性能。我们计划设计一种跨层优化方案，通过联合考虑来自物理层和上层的信息来优化分配子载波和功率资源。信息论和先进的排队论将结合在一起，对无线系统动力学进行建模。具体地说，研究了一种新的物理层信道估计方法来估计信道状态信息，并将其用于建立稳健的功率比特加载模型。建立了一种改进的马尔可夫调制泊松过程(MMPP)排队模型，用于模拟上层异质多媒体应用的服务质量性能。在调度器处，建立跨层多目标优化，寻求低复杂度的算法来搜索联合副载波和功率分配的最优解。该项目的成果将为加快新兴的下一代宽带无线接入系统在英国和全球的快速和无处不在的部署做出重大贡献。

There is a growing demand that future networks should be ubiquitous, pervasive and multimedia-capable, i.e. anyone should have broadband access at anytime and anywhere. This demands that the future network access should be broadband, high-speed, and with Quality of Service (QoS) support for various multimedia applications. This vision will not become true without the development of next-generation QoS-enabled broadband wireless access technologies given that the current access technologies (e.g. WiFi, GSM/GPRS/3G UMTS and DSL cable access) cannot sufficiently satisfy the above requirements. Orthogonal Frequency Division Multiple Access (OFDMA) technology has emerged as a most promising transmission technique candidate to be utilized for the next-generation broadband wireless access networks. Compared to conventional single-carrier systems, the orthogonal multi-carrier transmission scheme offers increased robustness to mitigate wireless multi-path distortion effects, and any subsets of the available subcarriers can be flexibly assigned to any users according to their specific QoS requirements.This proposal seeks to explore effective solutions for managing radio and transmission power resources to guarantee the QoS performance as perceived by users with minimum transmission power consumption for emerging OFDMA-based broadband wireless access systems. We plan to design a cross-layer optimization scheme, where subcarrier and power resources are optimally allocated by jointly considering the information from both physical and upper layers. Information theory and advanced queuing theory will be combined together for modelling wireless system dynamics. Specifically, a novel channel estimation method is to be investigated for physical layer to estimate channel state information, and then to be utilized to formulate a robust power bit loading model. An advanced Markov Modulated Poisson Process (MMPP) queuing model is to be created for modelling QoS performance of upper layer heterogeneous multimedia applications. At the scheduler, a cross-layer multi-objective optimization will then be formulated and low-complexity algorithms are sought to search optimal solutions of joint subcarrier and power allocation. The outcomes of this project will make a significant contribution toward acceleration of the rapid and ubiquitous deployment of emerging next-generation broadband wireless access systems in the UK and worldwide.