Transmitter Optimization in Multiuser Wireless Systems with Quality of Service Constraints

In this dissertation, transmitter adaptation for optimal resource allocation in wireless communication systems are investigated. First, a multiple access channel model is considered where many transmitters communicate with a single receiver. This scenario is a basic component of a. wireless network in which multiple users simultaneously access the resources of a wireless service provider. Adaptive algorithms for transmitter optimization to meet Quality-of-Service (QoS) requirements in a distributed manner are studied. Second, an interference channel model is considered where multiple interfering transmitter-receiver pairs co-exist such that a given transmitter communicates with its intended receiver in the presence of interference from other transmitters. This scenario models a wireless network in which several wireless service providers share the spectrum to offer their services by using dynamic spectrum access and cognitive radio (CR) technologies. The primary objective of dynamic spectrum access in the CR approach is to enable use of the frequency band dynamically and opportunistically without creating harmful interference to licensed incumbent users. Specifically, CR users are envisioned to be able to provide high bandwidth and efficient utilization of the spectrum via dynamic spectrum access in heterogeneous networks. In this scenario, a distributed method is investigated for combined precoder and power adaptation of CR transmitters for dynamic spectrum sharing in cognitive radio systems. Finally, the effect of limited feedback for transmitter optimization is analyzed where precoder adaptation uses the quantized version of interference information or the predictive vector quantization for incremental updates. The performance of the transmitter adaptation algorithms is also studied in the context of fading channels

Resource allocation in DS-CDMA systems with side information at the transmitter

In a multiuser DS-CDMA system with frequency selectivity, each userâÂÂs spreading sequence is transmitted through a different channel and the autocorrelation and the cross correlation properties of the received sequences will not be the same as that of the transmitted sequences. The best way of designing spreading sequences for frequency selective channels is to design them at the receiver exploiting the usersâ channel characteristics. By doing so, we can show that the designed sequences outperform single user AWGN performance. In existing sequence design algorithms for frequency selective channels, the design is done in the time domain and the connection to frequency domain properties is not established. We approach the design of spreading sequences based on their frequency domain characteristics. Based on the frequency domain characteristics of the spreading sequences with unconstrained amplitudes and phases, we propose a reduced-rank sequence design algorithm that reduces the computational complexity, feedback bandwidth and improves the performance of some existing sequence design algorithms proposed for frequency selective channels. We propose several different approaches to design the spreading sequences with constrained amplitudes and phases for frequency selective channels. First, we use the frequency domain characteristics of the unconstrained spreading sequences to find a set of constrained amplitude sequences for a given set of channels. This is done either by carefully assigning an already existing set of sequences for a given set of users or by mapping unconstrained sequences onto a unit circle. Secondly, we use an information theoretic approach to design the spreading sequences by matching the spectrum of each userâÂÂs sequence to the water-filling spectrum of the userâÂÂs channel. Finally, the design of inner shaping codes for single-head and multi-head magnetic recoding channels is discussed. The shaping sequences are designed considering them as short spreading codes matched to the recoding channels. The outer channel code is matched to the inner shaping code using the extrinsic information transfer chart analysis. In this dissertation we introduce a new frequency domain approach to design spreading sequences for frequency selective channels. We also extend this proposed technique to design inner shaping codes for partial response channels

5G Outlook – Innovations and Applications

5G Outlook - Innovations and Applications is a collection of the recent research and development in the area of the Fifth Generation Mobile Technology (5G), the future of wireless communications. Plenty of novel ideas and knowledge of the 5G are presented in this book as well as divers applications from health science to business modeling. The authors of different chapters contributed from various countries and organizations. The chapters have also been presented at the 5th IEEE 5G Summit held in Aalborg on July 1, 2016. The book starts with a comprehensive introduction on 5G and its need and requirement. Then millimeter waves as a promising spectrum to 5G technology is discussed. The book continues with the novel and inspiring ideas for the future wireless communication usage and network. Further, some technical issues in signal processing and network design for 5G are presented. Finally, the book ends up with different applications of 5G in distinct areas. Topics widely covered in this book are: • 5G technology from past to present to the future• Millimeter- waves and their characteristics• Signal processing and network design issues for 5G• Applications, business modeling and several novel ideas for the future of 5