Simulation and Complexity Analysis of Iterative Interference Cancellation Receivers for LTE/LTE-Advanced

The paper details the simulation of a single user MIMO receiver operating according to the 3GPP/LTE standard applying a Parallel or Successive Interference Cancellation (PIC/SIC) strategy to a multicarrier (OFDMA/SC-FDMA) scheme. The algorithm details are analyzed and the PIC and SIC cancellation strategies are simulated and compared on random MIMO selective fading channels, considering limited complexities. The best PIC and SIC schemes for a given limited complexity (8 turbo decoding iterations per codeword) are compared for different codeblock lengths and spatial correlation scenarios over an EPA channel model. The 2 cycles SIC scheme shows the best performance over the selected scenarios, offering gains over the non-iterative schemes (measured at BLER values of 0.1) ranging from 1 to 4 dB in the considered cases. Larger gains are obtained with higher spatial correlation and shorter codeblock lengths. Better overall performance are obtained with lower spatial correlation and longer codeblock lengths

Frequency-Domain Turbo Equalisation in Coded SC-FDMA Systems: EXIT Chart Analysis and Performance

In this paper, we investigate the achievable performance of channel coded single-carrier frequency division multiple-access (SC-FDMA) systems employing various detection schemes, when communicating over frequency-selective fading channels. Specifically, three types of minimum mean-square error (MMSE) based frequency-domain (FD) turbo equalisers are considered. The first one is the turbo FD linear equaliser (LE). The second one is a parallel interference cancellation (PIC)-assisted turbo FD decision-feedback equaliser (DFE). The final one is the proposed hybrid interference cancellation (HIC)-aided turboFD-DFE, which combines successive interference cancellation (SIC) with iterative PIC and decoding. The benefit of interference cancellation (IC) is analysed with the EXtrinsic Information Transfer (EXIT) charts. The performance of the coded SC-FDMA systems employing the above-mentioned detection schemes is investigated with the aid of simulations. Our studies show that the IC techniques achieve an attractive performance at a moderate complexity

LTE uplink MIMO receiver with low complexity interference cancellation

In LTE/LTE-A uplink receiver, frequency domain equalizers (FDE) are adopted to achieve good performance. However, in multi-tap channels, the residual inter-symbol and inter-antenna interference still exist after FDE and degrade the performance. Conventional interference cancellation schemes can minimize this interference by using frequency domain interference cancellation. However, those schemes have high complexity and large feedback latency, especially when adopting a large number of iterations. These result in low throughput and require a large amount of resource in software defined radio implementation. In this paper, we propose a novel low complexity interference cancellation scheme to minimize the residual interference in LTE/LTE-A uplink. Our proposed scheme can bring about 2 dB gains in different channels, but only adds up to 7.2 % complexity to the receiver. The scheme is further implemented on Xilinx FPGA. Compared to other conventional interference cancellation schemes, our scheme has less complexity, less data to store, and shorter feedback latency.Renesas MobileTexas IntrumentsXilinxSamsungHuaweiNational Science Foundation (NSF

Non-Orthogonal Narrowband Internet of Things: A Design for Saving Bandwidth and Doubling the Number of Connected Devices

IEEE Narrowband IoT (NB-IoT) is a low power wide area network (LPWAN) technique introduced in 3GPP release 13. The narrowband transmission scheme enables high capacity, wide coverage and low power consumption communications. With the increasing demand for services over the air, wireless spectrum is becoming scarce and new techniques are required to boost the number of connected devices within a limited spectral resource to meet the service requirements. This work provides a compressed signal waveform solution, termed fast-orthogonal frequency division multiplexing (Fast-OFDM), to double potentially the number of connected devices by compressing occupied bandwidth of each device without compromising data rate and bit error rate (BER) performance. Simulation is firstly evaluated for the Fast-OFDM with comparisons to single-carrier-frequency division multiple access (SC-FDMA). Results indicate the same performance for both systems in additive white Gaussian noise (AWGN) channel. Experimental measurements are also presented to show the bandwidth saving benefits of Fast-OFDM. It is shown that in a line-of-sight (LOS) scenario, Fast-OFDM has similar performance as SC-FDMA but with 50% bandwidth saving. This research paves the way for extended coverage, enhanced capacity and improved data rate of NB-IoT in 5th generation (5G) new radio (NR) networks

Implementação de um sistema de comunicações móveis para o Uplink

Mestrado em Engenharia Electrónica e TelecomunicaçõesÉ evidente que actualmente cada vez mais a internet móvel está presente na vida das sociedades. Hoje em dia é relativamente fácil estar ligado à internet sempre que se quiser, independentemente do lugar onde se encontra (conceito: anytime and anywhere). Desta forma existe um número crescente de utilizadores que acedem a serviços e aplicações interactivas a partir dos seus terminais móveis. Há, portanto, uma necessidade de adaptar o mundo das telecomunicações a esta nova realidade, para isso é necessário implementar novas arquitecturas que sejam capazes de fornecer maior largura de banda e reduzir os atrasos das comunicações, maximizando a utilização dos recursos disponíveis do meio/rede e melhorando assim a experiência do utilizador final. O LTE representa uma das tecnologias mais avançadas e de maior relevância para o acesso sem fios em banda larga de redes celulares. OFDM é a tecnologia base que está por traz da técnica de modulação, bem como as tecnologias adjacentes, OFDMA e SC-FDMA, usadas especificamente no LTE para a comunicação de dados descendente (downlink) ou ascendente (uplink), respectivamente. A implementação de múltiplas antenas em ambos os terminais, potenciam ainda mais o aumento da eficiência espectral do meio rádio permitindo atingir grandes taxas de transmissão de dados. Nesta dissertação é feito o estudo, implementação e avaliação do desempenho da camada física (camada 1 do modelo OSI) do LTE, no entanto o foco será a comunicação de dados ascendente e a respectiva técnica de modelação, SC-FDMA. Foi implementada uma plataforma de simulação baseada nas especificações do LTE UL onde foram considerandos diferentes esquemas de antenas. Particularmente para o esquema MIMO, usou-se a técnica de codificação no espaço-frequência proposta por Alamouti. Foram também implementados vários equalizadores. Os resultados provenientes da simulação demonstram tanto a eficiência dos diversos modos de operação em termos da taxa de erro, como o excelente funcionamento de processos de mapeamento e equalização, que visam melhorar a taxa de recepção de dados.It is clear that mobile Internet is present in the life of societies. Nowadays it is relatively easy to be connected to the internet whenever you want, no matter where you are (concept: anytime and anywhere). Thus, there are a growing number of users accessing interactive services and applications from their handsets. Therefore, there is a need to adapt the world of telecommunications to this new reality, for that it is necessary to implement new architectures that are able to provide higher bandwidth and reduce communication delays, maximizing use of available resources in the medium/network and thereby improving end-user experience. LTE represents one of the most advanced architectures and most relevant to wireless broadband cellular networks. OFDM is the technology that is behind the modulation technique and the underlying technologies, OFDMA and SCFDMA, used specifically in LTE for data communication downward (downlink) or upward (uplink), respectively. The implementation of multiple antennas at both ends further potentiate the increase of spectral efficiency allowing to achieve high rates of data transmission. In this dissertation is done the study, implementation and performance evaluation of the physical layer (OSI Layer 1) of the LTE, but the focus will be communication and its upstream data modeling technique, SC-FDMA. We implemented a simulation platform based on LTE UL specifications where were considered different antenna schemes. Particularly for the MIMO scheme, we used the technique of space-frequency coding proposed by Alamouti. We also implemented several equalizers. The results from the simulation demonstrate both the efficiency of different modes of operation in terms of error rate, as the excellent operation of mapping processes and equalization, designed to improve the rate of receiving data