【作者】 王心霖；

【导师】 许成谦；

【作者基本信息】 燕山大学 ， 通信与信息系统， 2010， 硕士

【摘要】 随着无线通信网络的快速发展,对高数据速率和高服务质量的要求也在日益增长。然而,无线信道的衰落特性却严重降低了数据链路的传输性能。因此,相对于有线通信,无线系统的数据吞吐量在很大程度上被其信道特性所限制。吞吐量通常被定义为数据接收端成功接收数据的速率,它是通信系统服务质量好坏的重要标准。为实现无线系统吞吐量的提高,物理层中基于正交幅度调制实现的自适应调制编码和链路层中自动重传协议得到了广泛研究,但在这些研究中控制复杂度、系统整体性能和耗能的有效性上仍有许多不足。首先,为准确和快速利用信噪比计算此时信道状态下的系统最佳的控制参数,本文针对信道特性在加性高斯白噪声条件下以格雷码编码的正交幅度调制提出了一种基于位判决线为参照结合各信息位格雷码扩展规律的误码率计算方法,并推导了其精确计算模型和提出了一种快速近似计算方法,并通过仿真验证了其精确性和近似性。其次,相对于自适应调制编码和自动重传协议的分层控制,本文基于跨层设计的思想,以物理层的正交幅度调制为基础并结合数据链路层的自动重传和包长控制协议设计了基于最佳子包分割数机制控制下的自适应调制编码结合自动重传的跨层优化控制协议。该协议以接收端反馈到发射端的信噪比作为跟踪信道状态的依据来进行实时控制,并以最大化系统吞吐量为准则,给出了子包数目和调制编码方式联合选择的最优方法。最后,以本文的跨层控制协议为基础综合考虑系统参数和数据负载对能耗的影响,建立了基于无线传感器网络以每数据比特等效能耗为目标的数学模型。并通过仿真,分析和研究了在实现数据吞吐量最大化的过程中传输数据对能耗有效性的影响。更多还原

【Abstract】 In wireless communication networks, the demand for high data rates and quality of service (QoS) is growing at a rapid pace. However, the performance of wireless links is severely degraded due to channel fading, which limits the overall system throughput considerably relative to wired-line alternatives. Throughput, defined as the data rate successfully received, is a key measure of quality of service (QoS) for wireless data transmission systems. To enhance throughput in future wireless data communication systems, adaptive modulation and coding (AMC) at the physical layer and automatic repeat request (ARQ) protocol at the data link layer have been studied extensively, while they also have many obvious defects in aspects of complexity, overall performance, energy consumption and so on.At first, this paper has been proposed an exact and general closed-form expression of the BER performance for the Quadrature Amplitude odulation (QAM), under an AWGN channel when Gray code mapping is employed. And by simulation to verify its accuracy and the approximateSecond, Compared with the separated control of adaptive modulation and coding, and automatic re-transmission protocol on the layer, in this paper, based on the idea of cross-layer design, the cross-layer protocol of adaptive modulation and coding combined with automatic retransmission control under the best number of Separate sub-package is designed based on AMC at the physical layer and ARQ at the data link laye. The protocol with the receiver back to the transmitter SNR as the basis for tracking channel state conduct real-time control. And to maximize system throughput as the goal, the method is given to choose jointly the number of sub-packet and the class of modulation coding. Finally, to the cross-layer control protocol based on comprehensive consideration of system parameters and data load on the impact of energy consumption, a mathematical model of a wireless sensor network based on the data per-bits energy equivalent is established in this paper. And through simulation, analysis and research the data throughput in the process of maximizing the effectiveness of transferring data on the impact of energy consumption.更多还原