Wireless communication

Scientists Compare Phase Noise With Vector OFDM

Orthogonal frequency division multiplexing (OFDM), which is used in a range of wireless communication technologies, is a specific subcase of vector OFDM (V-OFDM). V-OFDM generally outperforms OFDM, as it does in scenarios with multipath diversity. To expand upon the ever-present study of V-OFDM techniques for single-transmit antenna systems, a phase-noise estimation and compensation method has been analyzed and developed by the following researchers: Ibo Ngebani, Yabo Li, Xiang-Gen Xia, Sami Ahmed Haider, Aiping Huang, and Minjian Zhao. According to the team, their approach exceeds the performance of OFDM methods.

In an OFDM system, performance is degraded via intercarrier interference and common phase error, which result from the introduction of phase noise. In V-OFDM systems, however, phase noise results in inter-vector-block carrier interference and common-vector-block phase error (CVBPE). To counteract these degrading effects for V-OFDM systems, the researchers developed a pilot vector CVBPE estimation technique. To successfully estimate phase noise, they combined a linear minimum mean square error and maximum likelihood estimator.

In terms of complexity, the phase-noise estimation technique for V-OFDM was found to be less complex than it is for OFDM systems. This discovery could lead to cheaper and smaller ICs for wireless technologies, such as WiFi. Advancing beyond simple estimation, the team used a decorrelation and cancellation technique. They then compensated the V-OFDM system for phase noise. The end result of this process produced performance comparable to a phase-noise-free environment.

See “Analysis and Compensation of Phase Noise in Vector OFDM Systems,” IEEE Transactions on Signal Processing, Dec. 2014, p. 6143-6157.

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