Time-Hopping Multicarrier Code-Division Multiple-Access

A time-hopping multicarrier code-division multiple-access (TH/MC-CDMA) scheme is proposed and investigated. In the proposed TH/MC-CDMA each information symbol is transmitted by a number of time-domain pulses with each time-domain pulse modulating a subcarrier. The transmitted information at the receiver is extracted from one of the, say $M$, possible time-slot positions, i.e., assuming that $M$-ary pulse position modulation is employed. Specifically, in this contribution we concentrate on the scenarios such as system design, power spectral density (PSD) and single-user based signal detection. The error performance of the TH/MC-CDMA system is investigated, when each subcarrier signal experiences flat Nakagami-$m$ fading in addition to additive white Gaussian noise (AWGN). According to our analysis and results, it can be shown that the TH/MC-CDMA signal is capable of providing a near ideal PSD, which is flat over the system bandwidth available, while decreases rapidly beyond that bandwidth. Explicitly, signals having this type of PSD is beneficial to both broadband and ultra-wide bandwidth (UWB) communications. Furthermore, our results show that, when optimum user address codes are employed, the single-user detector considered is near-far resistant, provided that the number of users supported by the system is lower than the number of subcarriers used for conveying an information symbol

Timing and Carrier Synchronization in Wireless Communication Systems: A Survey and Classification of Research in the Last 5 Years

Timing and carrier synchronization is a fundamental requirement for any wireless communication system to work properly. Timing synchronization is the process by which a receiver node determines the correct instants of time at which to sample the incoming signal. Carrier synchronization is the process by which a receiver adapts the frequency and phase of its local carrier oscillator with those of the received signal. In this paper, we survey the literature over the last 5 years (2010–2014) and present a comprehensive literature review and classification of the recent research progress in achieving timing and carrier synchronization in single-input single-output (SISO), multiple-input multiple-output (MIMO), cooperative relaying, and multiuser/multicell interference networks. Considering both single-carrier and multi-carrier communication systems, we survey and categorize the timing and carrier synchronization techniques proposed for the different communication systems focusing on the system model assumptions for synchronization, the synchronization challenges, and the state-of-the-art synchronization solutions and their limitations. Finally, we envision some future research directions

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

Multiuser MIMO-OFDM Systems using Subcarrier Hopping

Recently space division multiple access (SDMA) assisted multiple-input–multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems invoking multiuser detection (MUD) techniques have attracted substantial research interest, which is capable of exploiting both transmitter multiplexing gain and receiver diversity gain. A new scheme referred to here as slowsubcarrierhopping (SSCH) assisted multiuser SDMA-OFDM, is proposed. It is shown that, with the aid of the so-called uniform SSCH (USSCH) pattern, the multiuser interference (MUI) experienced by the high-throughput SDMA-OFDM system can be effectively suppressed, resulting in a significant performance improvement. In the investigations conducted, the proposed USSCH-aided SDMA-OFDM system was capable of outperforming a range of SDMA-OFDM systems considered, including the conventional SDMA-OFDM system dispensing with the employment of frequency-hopping techniques. For example, at an Eb/N0 value of 12 dB, the proposed USSCH/SDMA-OFDM system reduced the bit error ratio (BER) by about three orders of magnitude, in comparison to the conventional SDMA-OFDM system, while maintaining a similar computational complexity

Space time transceiver design over multipath fading channels

Imperial Users onl

On the theoretical aspects of multi-carrier spread spectrum systems.

by Tsan-Fai Ho.Thesis (M.Phil.)--Chinese University of Hong Kong, 1996.Includes bibliographical references (leaves 64-68).Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Review on spread spectrum communications --- p.1Chapter 1.2 --- The spread spectrum techniques --- p.2Chapter 1.2.1 --- Direct Sequence (DS) Systems --- p.2Chapter 1.2.2 --- Frequency Hopping (FH) Systems --- p.2Chapter 1.2.3 --- Time Hopping (TH) Systems --- p.4Chapter 1.2.4 --- Hybrid Systems --- p.4Chapter 1.3 --- Existing Applications of the spread spectrum systems --- p.5Chapter 1.4 --- Organization of the thesis --- p.6Chapter 2 --- The Concept of Duality --- p.7Chapter 2.1 --- Multi-Carrier Systems - An Overview --- p.7Chapter 2.2 --- Orthogonal Frequency Division Multiplexing --- p.8Chapter 2.2.1 --- Bandwidth Efficiency --- p.9Chapter 2.2.2 --- Spectral Efficiency --- p.10Chapter 2.2.3 --- Effects of fading --- p.11Chapter 2.3 --- Applications of OFDM in multiple access --- p.13Chapter 2.3.1 --- ST-CDMA --- p.13Chapter 2.3.2 --- MC-DS-CDMA --- p.14Chapter 2.3.3 --- OFDM-CDMA --- p.15Chapter 2.4 --- Duality - Time-Frequency Interrelation --- p.16Chapter 3 --- Performance of Multi-Carrier CDMA System --- p.17Chapter 3.1 --- System Model --- p.17Chapter 3.2 --- Performance Analysis --- p.20Chapter 3.2.1 --- Gaussian Channel --- p.20Chapter 3.2.2 --- Fading Channel --- p.24Chapter 3.3 --- Performance with Pulse Shape --- p.33Chapter 3.4 --- Appendix --- p.34Chapter 4 --- Signal Design Criteria for MC-CDMA System --- p.36Chapter 4.1 --- Existence of Signal Distortion --- p.37Chapter 4.2 --- Measures of the Signal Envelope Fluctuation --- p.38Chapter 4.3 --- Complementary Sequences --- p.41Chapter 4.4 --- Crest Factors --- p.42Chapter 4.4.1 --- Time-limited Pulse --- p.43Chapter 4.4.2 --- Ideally Band-Limited Pulses --- p.43Chapter 4.4.3 --- Shaped Pulses --- p.45Chapter 4.5 --- Spectrally Efficient Complementary (SEC) Sequences --- p.48Chapter 4.6 --- Construction of Spectrally Efficient Complementary(SEC) Sequences --- p.50Chapter 4.7 --- Generalized Multiphase Spectrally Efficient Complementary Sequences --- p.55Chapter 5 --- Summary and Future Extensions --- p.58Chapter 5.1 --- Summary of the Results --- p.58Chapter 5.2 --- Topics for Future Research --- p.59AppendixChapter A --- Exhaustive search of MPSEC sequences --- p.61Chapter B --- Papers derived from this thesis --- p.63Bibliography --- p.6

Wavelet-based multi-carrier code division multiple access systems

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Link adaptation for MC-CDMA radio interface

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Multicarrier CDMA systems with MIMO technology

The rapid demand for broadband wireless access with fast multimedia services initiated a vast research on the development of new wireless systems that will provide high spectral efficiencies and data rates. A potential candidate for future generation wireless systems is multi-carrier code division multiple access (MC-CDMA). To achieve higher user capacities and increase the system data rate, various multiple-input multiple-output (MIMO) technologies such as spatial multiplexing and spatial diversity techniques have been proposed recently and combined with MC-CDMA.This research proposes a chip level coded ordered successive spatial and multiuser interference cancellation (OSSMIC) receiver for downlink MIMO MC-CDMA systems. As the conventional chip level OSIC receiver [1] is unable to overcome multiple access interference (MAI) and performs poorly in multiuser scenarios, the proposed receiver cancels both spatial and multiuser interference by requiring only the knowledge of the desired user's spreading sequence. Simulation results show that the proposed receiver not only performs better than the existing linear detectors [2] but also outperforms both the chip and symbol level OSIC receivers. In this work we also compare the error rate performance between our proposed system and MIMO orthogonal frequency division multiple access (MIMO OFDMA) system and we justify the comparisons with a pairwise error probability (PEP) analysis. MIMO MC-CDMA demonstrates a better performance over MIMO OFDMA under low system loads whereas in high system loads, MIMO OFDMA outperforms MIMO MC-CDMA. However if all users' spreading sequences are used at the desired user receiver, MIMO MC-CDMA performs better than MIMO OFDMA at all system loads.In the second part of this work, user grouping algorithms are proposed to provide power minimisation in grouped MC-CDMA and space-time block code (STBC) MC-CDMA systems. When the allocation is performed without a fair data rate requirement, the optimal solution to the minimisation problem is provided. However when some fairness is considered, the optimal solution requires high computational complexity and hence we solve this problem by proposing two suboptimal algorithms. Simulation results illustrate a significantly reduced power consumption in comparison with other techniques.EThOS - Electronic Theses Online ServiceEPSRCGBUnited Kingdo