Recent Wireless Communication Standards Research Articles

Experimental validation of orthogonal frequency division multiplexing with peak‐to‐average power ratio reduction and out‐band distortion control using software defined radio

Orthogonal frequency division multiplexing (OFDM) is an emerging technology in recent wireless communication standards where high data rate is required at low latency and better spectral efficiency. OFDM signals have a generic problem of high peak-to-average power ratio (PAPR) due to the superimposition of the data-modulated subcarriers. This high peak signals may result in amplifier non-linearity which creates many problems such as performance degradation and out-of-band distortion. Hence, the authors addressed this problem by designing and implementing four new PAPR reduction schemes such as phase modulation, rail clipping, sample and hold approach and threshold methods based on amplitude clipping to reduce PAPR and improve the band gap between spectral sidelobes to main lobe significantly. For practical proof of the suggested concepts, they have chosen software-defined radio as an experimental setup in which universal software radio peripheral N210 employed as hardware and GNU radio as software. Experimental results are analysed in terms of significant PAPR reduction and out-of-band spectral leakage control. Besides these, motivation, background and relevant mathematical analysis with rigid justification are presented in this study.

DESIGN AND IMPLEMENTATION OF TURBO CODER FOR LTE ON FPGA

Recent wireless communication standards such as 3GPP-LTE, WiMax, DVB-SH and HSPA incorporates turbo code for its excellent performance. This work provides an overview of the novel class of channel codes referred to as turbo codes, which have been shown to be capable of performing close to the Shannon Limit. It starts with a brief discussion on turbo encoding, and then move on to describing the form of the iterative decoder most commonly used to decode turbo codes. Here, Turbo decoder uses original MAP algorithm instead of using the approximated Max log-MAP algorithm thereby it reduces the number iterations to decode the transmitted information bits. This paper presents the FPGA (Field Programmable Gate Array) implementation simulation results for Turbo encoder and decoder structure for 3GPP-LTE standard.

High-Throughput and Area-Efficient MIMO Symbol Detection Based on Modified Dijkstra's Search

The multiple-input-multiple-output (MIMO) technique is being actively adopted in recent wireless communication standards to enhance data rate. Though channel capacity is increased by adopting multiple spatial streams, the computational complexity needed to eliminate the interference hinders the implementation of a practical system. In this paper, we propose a modified Dijkstra's algorithm and a precalculation technique to improve the throughput by allowing overlapped processing. For the maximum-likelihood (ML) detection, in addition, we propose a simple approximation of L2-norm calculation to reduce the computational complexity without degrading the error performance noticeably. A MIMO symbol detector based on the proposed algorithm is implemented in a 0.18- μm CMOS process, targeting 4 × 4 16-QAM. It occupies about 0.5 mm2 with 25.1 K equivalent gates and shows a throughput of over 300 Mb/s.