Development of Simulation Components for Wireless Communication

abstract: This thesis work present the simulation of Bluetooth and Wi-Fi radios in real life interference environments. When information is transmitted via communication channels, data may get corrupted due to noise and other channel discrepancies. In order to receive the information safely and correctly, error correction coding schemes are generally employed during the design of communication systems. Usually the simulations of wireless communication systems are done in such a way that they focus on some aspect of communications and neglect the others. The simulators available currently will either do network layer simulations or physical layer level simulations. In many situations, simulations are required which show inter-layer aspects of communication systems. For all such scenarios, a simulation environment, WiscaComm which is based on time-domain samples is built. WiscaComm allows the study of network and physical layer interactions in detail. The advantage of time domain sampling is that it allows the simulation of different radios together which is better than the complex baseband representation of symbols. The environment also supports study of multiple protocols operating simultaneously, which is of increasing importance in today's environment.Dissertation/ThesisMasters Thesis Electrical Engineering 201

The Gaussian Approximation to Multiple-Access Interference in the Evaluation of the Performance of a Communication System with Convolutional Coding and Viterbi Decoding

The standard Gaussian approximation is extended to the performance analysis of direct-sequence code-division multiple-access (DS-CDMA) systems using binary con-volutional coding, quaternary modulation with quaternary direct-sequence spreading and Viterbi decoding. Using the standard Gaussian approximation, the random variables mod-eling the multiple-access interference in the receiver statistics are replaced by an equivalent additive Gaussian noise term with the same variance as the actual multiple-access interfer-ence term. The Gaussian approximation is shown to result in an accurate approximation to the probability of code-word error at the receiver. The accuracy is demonstrated by compar-ing simulation results for the actual multiple-access system and a model using the standard Gaussian approximation. Both are compared with two previously developed closed-form bounds on the performance: the concave-first-event bound and the concave-integral bound

Hybrid ARQ with parallel and serial concatenated convolutional codes for next generation wireless communications

This research focuses on evaluating the currently used FEC encoding-decoding schemes and improving the performance of error control systems by incorporating these schemes in a hybrid FEC-ARQ environment. Beginning with an overview of wireless communications and the various ARQ protocols, the thesis provides an in-depth explanation of convolutional encoding and Viterbi decoding, turbo (PCCC) and serial concatenated convolutional (SCCC) encoding with their respective MAP decoding strategies.;A type-II hybrid ARQ scheme with SCCCs is proposed for the first time and is a major contribution of this thesis. A vast improvement is seen in the BER performance of the successive individual FEC schemes discussed above. Also, very high throughputs can be achieved when these schemes are incorporated in an adaptive type-II hybrid ARQ system.;Finally, the thesis discusses the equivalence of the PCCCs and the SCCCs and proposes a technique to generate a hybrid code using both schemes

Acceleration of High-Fidelity Wireless Network Simulations

Network simulation with bit-accurate modeling of modulation, coding and channel properties is typically computationally intensive. Simple link-layer models that are frequently used in network simulations sacrifice accuracy to decrease simulation time. We investigate the performance and simulation time of link models that use analytical bounds on link performance and bit-accurate link models executed in Graphical Processing Units (GPUs). We show that properly chosen analytical bounds on link performance can result in simulation results close to those using bit-level simulation while providing a significant reduction in simulation time. We also show that bit-accurate decoding in link models can be expedited using parallel processing in GPUs without compromising accuracy and decreasing the overall simulation time

Packet data communications over coded CDMA with hybrid type-II ARQ

This dissertation presents in-depth investigation of turbo-coded CDNIA systems in packet data communication terminology. It is divided into three parts; (1) CDMA with hybrid FEC/ARQ in deterministic environment, (2) CDMA with hybrid FEC/ARQ in random access environment and (3) an implementation issue on turbo decoding. As a preliminary, the performance of CDMA with hybrid FEC/ARQ is investigated in deterministic environment. It highlights the practically achievable spectral efficiency of CDMA system with turbo codes and the effect of code rates on the performance of systems with MF and LMMSE receivers, respectively. For given ensemble distance spectra of punctured turbo codes, an improved union bound is used to evaluate the error probability of ML turbo decoder with MF receiver and with LMMSE receiver front-end and, then, the corresponding spectral efficiency is computed as a function of system load. In the second part, a generalized analytical framework is first provided to analyze hybrid type-11 ARQ in random access environment. When applying hybrid type-11 ARQ, probability of packet success and packet length is generally different from attempt to attempt. Since the conventional analytical model, customarily employed for ALOHA system with pure or hybrid type-I ARQ, cannot be applied for this case, an expanded analytical model is introduced. It can be regarded as a network of queues and Jackson and Burke\u27s theorems can be applied to simplify the analysis. The second part is further divided into two sub topics, i.e. CDMA slotted ALOHA with hybrid type-11 ARQ using packet combining and CDMA unslotted ALOHA with hybrid type-11 ARQ using code combining. For code combining, the rate compatible punctured turbo (RCPT) codes are examined. In the third part, noticing that the decoding delay is crucial to the fast ARQ, a parallel MAP algorithm is proposed to reduce the computational decoding delay of turbo codes. It utilizes the forward and backward variables computed in the previous iteration to provide boundary distributions for each sub-block MAP decoder. It has at least two advantages over the existing parallel scheme; No performance degradation and No additional computation

Techniques for improving the performance of frequency-hopped multiple-access communication systems

Imperial Users onl

New Analytical Bounds on the Probability of Code-Word Error for Convolution Codes with Viterbi Decoding

New analytical bounds are developed for the probability of code-word error in a communication system with convolutional coding and soft-decision Viterbi decoding. The bounds are applicable to communications in channels with asynchronous interferers which are modeled as independent, partial-time white Gaussian interference sources. This model is often used in simulations to reflect the circumstances encountered in many packet radio communication networks. The new results include both purely analytical bounds and offline-simulation-aided bounds that permit implementation of accurate communication-link models with much lower online computational and storage requirements than are required with traditional Monte Carlo simulations of link performance. They significantly improve the trade-off that has previously existed between model fidelity and simulation complexity in Monte Carlo simulations of large-scale wireless communication networks with links employing convolutional coding

Underwater acoustic communications and adaptive signal processing

This dissertation proposes three new algorithms for underwater acoustic wireless communications. One is a new tail-biting circular MAP decoder for full tail-biting convolution (FTBC) codes for very short data blocks intended for Internet of Underwater Things (IoUT). The proposed algorithm was evaluated by ocean experiments and computer simulations on both Physical (PHY) and Media access control (MAC) layers. The ocean experimental results show that without channel equalization, the full tail-biting convolution (FTBC) codes with short packet lengths not only can perform similarly to zero-tailing convolution (ZTC) codes in terms of bit error rate (BER) in the PHY layer. Computer simulation results show that the FTBC codes outperform the ZTC codes in terms of MAC layer metrics, such as collision rate and bandwidth utilization, in a massive network of battery powered IoUT devices. Second, this dissertation also proposes a new approach to utilizing the underwater acoustic (UWA) wireless communication signals acquired in a real-world experiment as a tool for evaluating new coding and modulation schemes in realistic doubly spread UWA channels. This new approach, called passband data reuse, provides detailed procedures for testing the signals under test (SUT) that change or add error correction coding, change bit to symbol mapping (baseband modulation) schemes from a set of original experimental data --Abstract, page iv