Comparative Evaluation of UMTS, WLAN, BWA, MBWA, and UWB Systems

UMTS, WLAN, BWA and UWB systems are compared in this paper. The comparative analysis covers system capacity, QoS, and radiowave propagation

Viability of concurrent transmission and reception for UWB radios over multipath channels

Multihop transmissions over wireless mesh networks present limited end-to-end (E2E) data rates, as every hop waits for an entire packet to arrive before starting retransmission. That is, the E2E data rate drops when every hop stores and then forwards packets, thus making such transmissions unsuitable for multimedia applications. In this work, in order to increase data rates, we present an ultra-wideband (UWB) radio transceiver capable of concurrently transmit and receive (cTxRx) packets. However, concurrently receiving and transmitting comes at the cost of a channel model with increased interference level. Herein, we explain a new interference model and propose a transceiver that compensates for it. We describe the transceiver mathematically and analyze its performance via simulations. Also, we demonstrate that the E2E data rate exceeds that of current multihop transmissions, thus allowing multimedia traffic to be transmitted over a multi-hop wireless mesh network

[[alternative]]System Evaluation, Simulation Platform Set Up and Baseband Circuit Implementation for Wireless Sensor Network

計畫編號：NSC93-2213-E032-023研究期間：200408~200507研究經費：515,000[[abstract]]本計畫分三年以實現無線感測網路之系統評估模擬平台建置與基頻電路研製。本計劃研 究子題如下： (A) IEEE 802.15.4 系統之分析及設計 1. 媒介擷取控制層與實體層間之介面設計 2. 系統架構的確定，系統規格及各子方塊之間之介面規格之訂定 3. 低功率基頻電路的設計及探討 4. 接收機技術研究(同步、通道等化、信號偵測等) 5. 利用 ADS 與 Matlab 以建立模擬平台 6. 傳送端與接收端低功率基頻電路之硬體實現 (B) IEEE 802.15.4a 系統之分析及設計 1. UWB 基本原理之研究與探討 2. UWB 傳送與接收基本技術之研究 3. 利用 ADS 及 Matlab 建立模擬平台，對 UWB 之架構模擬 4. UWB 基本方塊規格之訂定 5. 精確定位之研究 (C) IEEE 802.15.4 之MIMO 架構設計 1. MIMO 架構之演算法與架構之研究 2. MIMO 架構之用於IEEE 802.15.4 之通道效應之探討與研究 3. 利用MIMO 架構傳送MPEG-4 之效能探討 4. MIMO 架構之接收技術之研究 5. 利用 ADS 及 Matlab 建立性模擬平台以研究多頻帶的傳輸特性 6. 探討如何利用基頻電路的切換以達低功率而高速的信號傳送 (D) 通道分析及模型的建立 1. 通道傳送損失特性之分析 2. 路徑衰減及多重路徑之分析 3. 路徑衰減之經驗公式推導 4. 通道模型之建立 5. 通道等化器演算法之推導及分析(E) 模擬平台的建立 1. 利用 ADS 程式以建立基頻及 RF 端之模擬平台 2. 利用 Matlab 程式以建立基頻及 RF 端之模擬平台 3. 基頻及 RF 端 ADS 模擬平台的介面設計 4. 基頻及 RF 端 Matlab 模擬平台的介面設計 5. 系統特性的模擬及數據分析 (F) 測試平台的建立 1. IEEE 802.15.4 實體層各子方塊之 Verilog 程式燒錄至 FPGA 並測試 2. IEEE 802.15.4 實體層整合電路之 Verilog 程式燒錄至 FPGA 並測試 3. Mulit-Band 實體層之 Verilog 程式燒錄至 FPGA 並測試 4. IEEE 802.15.4 實體層 ASIC 之測試 5. IEEE 802.15.4 實體層 ASIC 與 RF 之整合測試 6. IEEE 802.15.4 實體層 ASIC 與 MAC 之整合測試 7. IEEE 802.15.4 實體層 ASIC , MAC 及 RF 之整合測試[[sponsorship]]行政院國家科學委員

On the performance and capacity of space-time block coded multicarrier CDMA communication systems

Ph.DDOCTOR OF PHILOSOPH

Target Localization Using Approximate Maximum Likelihood for MIMO Radar Systems

This thesis deals with target localization using multiple-input multiple-output (MIMO) radars. In the field of communications, navigation, radar, and sensing networks, one of the common and most sophisticated problems is target localization. We develop a target localization scheme in distributed MIMO radar systems using bistatic range measurements. The localization approach consists of two phases. First, measurements are divided into multiple groups based on the various transmitter and receiver elements. For each group, an approximate maximum likelihood (AML) estimator is proposed to estimate the location of a target. Then, the estimation results from these different groups are combined to form the final estimate. The performance of the proposed algorithm is validated by simulation and is shown to reach the Cram\'{e}r-Rao lower bound (CRLB) in a range of measurement noise levels. The main advantage of the proposed algorithm is that it achieves a higher accuracy than existing schemes for locating a target position in high-noise conditions

Implementation of multi carrier-code division multiple access-frequency division multiple access with beyond 4G specifications

Hybrid code division multiple access techniques present the open door for the future of code division multiple access and wireless communications. Multicarrier CDMA is the most popular type of hybrid CDMA because of its robustness against multipath fading channels and flexible multiple access capability. MC-CDMA is a predictable technique for future high data rate wireless communication systems according to these appealed properties. The main drawback of MC-CDMA is the power level in uplink, i.e. the ratio of peak power to the average power is high and leads to high instantaneous power which is required in transmission of mobile station. However, there are many researchers working towards reducing the level of the transmitted power. This research presents new method of peak to average power ratio (PAPR) reduction. The proposed method is making use of the characteristics of uplink for current 4th Generation (single carrier frequency division multiple access) which has low PAPR into current MC-CDMA system to reproduce a new MC-CDMA system (MC-CDMA-FDMA) with low PAPR and keep all the characteristics of the basic MC-CDMA system. MC-CDMA-FDMA reduced the level of power from 10 dB to 2 dB in case of 64 FFT size and Walsh Hadamard code is used in spreading block. In addition bit error rate has been reduced from 96x10-5 bps to 82x10-5 bps comparing to SC-FDMA bit error rate. The proposed system also has high flexibility to deal with modern communication systems with minimum required hardware at the base station through optimization of FFT size. The simulation results show that MC-CDMA-FDMA system will be a good candidate for beyond 4th Generation for mobile communication