Improvements and New Techniques for Deterministic and Stochastic SIR based Power Control for 3-G Wireless CDMA Networks

3-G 无线 CDMA 网络基于确定性和随机 SIR 功率控制的改进和新技术

• 批准号: 0106857
• 负责人: Zoran Gajic
• 金额: $ 25.95万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-10-01 至 2005-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0106857&HistoricalAwards=false
• 关键词: Improvements; New; Techniques; Deterministic; Stochastic

The proposed research is about the use of optimal control theory and modern numerical linear algebratechniques to improve existing power control schemes and to formulate and solve more general and morerealistic formulations of power control problem in 3-G wireless CDMA networks. The first two parts of theproposal deal with the deterministic power control problem and its variants, and the third part is onstochastic versions of the same problem. In the first part of the proposed research, an improvement of distributed constrained power controlalgorithm (PCPC), which is presently considered in the literature as the most efficient one, is suggestedvia the use of the acceleration techniques for fixed-point iterations and via the use Krylov subspaceiterations (presently considered as the most efficient numerical method for solving systems of linearlarge scale algebraic equations). The second part of the proposal considers an optimal fast closed-loop SIR-based power controlscheme for 3-G wireless CDMA network, based on the recent research work of the author of this proposaland his doctoral student. In addition of being optimal, the scheme obtained theoretically converges in oneiteration. This scheme follows perfectly channel variations and assumes that the link gains constantlychange in time. Due to the fact that the scheme needs a scalar discrete-time estimator (predictor), itpractically converges in 4-5 iterations. Simulations on a CDMA system demonstrate the effectiveness ofthe optimal power control algorithm and its superiority over the corresponding IS-95 algorithm and thepresent version of the DCPC algorithm. As a future research topic, a comparative analysis between theoptimized power control algorithm and the improved versions of the DCPC algorithm (accelerated andKrylov subspace based) to be obtained in the first part of this proposal, is suggested first. Secondly, sinceduring optimization, the weighted sum of the transmission power and the SIR (signal-to-interference)error, are jointly optimized, the power control problem can be put in the framework of Nash dynamicgames. It is suggested to extend the optimized power control results to capture the conflict situationamong users in a wireless network, which leads to the formulation of a Nash dynamic game problem. The third part of this proposal deals with the stochastic formulation of the power control problem. Thisis a pretty much new and widely open research problem. The basic problem formulation extends thedeterministic optimized power control problem to a stochastic environment, and leads to the linear powerevolution equation with additive Gaussian white noise. This problem formulation assumes that either linkgains or background noise or both are modeled as Gaussian white noise stochastic processes. Its variantof colored background noise and colored link gains noise are also suggested for future research. Inaddition, more realistic situations of state- and control-dependent noise using optimal control theoryresults will be considered. The control variables will be the ones that regulate the convergence process ofthe state variables (transmission powers and SIR errors) to their optimal values in a noisy environment.Note that the state- and control-dependent noise optimal control problems in discrete-time domain havebeen solved recently in the optimal control literature. In the final stage of this proposal, it is suggested tostudy the power control problem assuming that the link gains change according to Poisson stochasticprocesses. The impact of the proposed research will be in the area of improvements of the capacity of 3-Gwireless CDMA networks, reliability of quality of service (QoS) and durability of user's battery life. Allthese will be achieved by controlling interference in an optimal manner.

本论文的主要研究内容是利用最优控制理论和现代数值线性代数技术来改进现有的功率控制方案，并建立和求解更一般、更现实的3-G无线CDMA网络功率控制问题的公式。该提案的前两部分处理确定性功率控制问题及其变体，第三部分是同一问题的随机版本。 在所提出的研究的第一部分中，改进的分布式约束功率控制算法（PCPC），这是目前在文献中被认为是最有效的一个，通过使用加速技术的固定点迭代和通过使用Krylov子空间迭代（目前被认为是最有效的数值方法求解线性大规模代数方程组）。 论文的第二部分是在作者及其博士生近期研究工作的基础上，提出了一种适用于3G无线CDMA网络的基于SIR的最优快速闭环功率控制方案。所得到的格式不仅是最优的，而且理论上在一次迭代中收敛。该方案完全遵循信道变化，并假设链路增益随时间不断变化。由于该方案需要一个标量离散时间估计器（预报器），因此它实际上在4-5次迭代中收敛。在CDMA系统上的仿真结果表明了最优功率控制算法的有效性，并与相应的IS-95算法和现有的DCPC算法相比具有明显的优越性。作为一个未来的研究课题，优化的功率控制算法和DCPC算法的改进版本（加速和Krylov子空间为基础）之间的比较分析，将在本建议的第一部分中获得，建议第一。其次，在优化过程中，由于发射功率和信干比误差的加权和是联合优化的，因此功率控制问题可以放在Nash动态博弈的框架中进行求解。最后，提出了一种基于最优功率控制的无线网络中用户间冲突的解决方案，并将其转化为一个纳什动态博弈问题。 本建议的第三部分涉及功率控制问题的随机公式化。这是一个相当新的和广泛开放的研究问题。基本问题形式将确定性最优功率控制问题扩展到随机环境中，得到了加性高斯白色噪声下的线性功率旋转方程。这个问题的制定假设，无论是linkgains或背景噪声或两者都建模为高斯白色噪声随机过程。并提出了其有色背景噪声和有色链路增益噪声的变体，供今后研究参考.此外，更现实的情况下，状态和控制相关的噪声使用最优控制理论的结果将被考虑。控制变量将是那些调节收敛过程的状态变量（传输功率和SIR误差），以他们的最佳值在一个嘈杂的environment.Note的状态和控制相关的噪声最优控制问题在离散时间域已解决最近在最优控制文献。在最后阶段的建议，它建议研究的功率控制问题，假设链路增益的变化根据泊松随机过程。 所提出的研究的影响将在该地区的3-Gwireless CDMA网络的容量，服务质量（QoS）的可靠性和用户的电池寿命的耐久性的改进。所有这些都将通过以最佳方式控制干扰来实现。