Capacity and BER performance improvement in integrated MIMO-OFDM system using optimal power allocation, channel estimation, and turbo coding,International Journal of Communication Systems

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Capacity and BER performance improvement in integrated MIMO-OFDM system using optimal power allocation, channel estimation, and turbo coding
International Journal of Communication Systems ( IF 1.7 ) Pub Date : 2021-07-13 , DOI: 10.1002/dac.4915
Srinu Pyla ₁ , Padma Raju K , Bala Subrahmanyam N ₁

Affiliation

Among communication systems, multiple input multiple output (MIMO) system has the capability of providing spectral efficiency, high data rates, diversity gain, and improved reliability. Suitably designed orthogonal frequency division multiplexing (OFDM) transmits the signal without inter symbol interference and multipath fading. Hence, MIMO-OFDM is a strong candidate for 4G and 5G wireless systems. However, variations in signal-to-noise ratio (SNR) due to the random nature of the channel and poor capacity at low SNR are critical issues in conventional MIMO-OFDM system. This paper explains how optimal power allocation (OPA), channel estimation, and coding improve the capacity and bit error rate (BER) performance of MIMO-OFDM system. In OPA, the transmitter power is distributed adaptively to the channels based on the SNR statistics using singular value decomposition and water filling algorithm. In case of low SNR, less number of channels are selected for power allocation. Least squares (LS), minimum mean square error (MMSE), and least mean square (LMS) estimators are considered in comb type pilot channel estimation while turbo code is used with code rates of 1/2 and 1/3. From the simulation results, capacity improvement of 5 b/s/Hz and 11 b/s/Hz is observed for MIMO-OFDM systems with four antennas and eight antennas, respectively. It is also found that performance of LMS estimator improved by 3.5-dB SNR over LS and 1 dB SNR over MMSE. In this paper is shown how LMS estimator and 1/3 turbo code have been integrated with MIMO-OFDM, and this has resulted in around 4-dB SNR improvement over conventional MIMO-OFDM.

中文翻译：

使用最佳功率分配、信道估计和 Turbo 编码提高集成 MIMO-OFDM 系统的容量和 BER 性能

在通信系统中，多输入多输出 (MIMO) 系统具有提供频谱效率、高数据速率、分集增益和提高可靠性的能力。适当设计的正交频分复用 (OFDM) 可以在没有符号间干扰和多径衰落的情况下传输信号。因此，MIMO-OFDM 是 4G 和 5G 无线系统的有力候选。然而，由于信道的随机性和低 SNR 下的低容量导致的信噪比 (SNR) 变化是传统 MIMO-OFDM 系统中的关键问题。本文解释了最佳功率分配 (OPA)、信道估计和编码如何提高 MIMO-OFDM 系统的容量和误码率 (BER) 性能。在 OPA 中，使用奇异值分解和注水算法，基于 SNR 统计，将发射机功率自适应地分配到信道。在低 SNR 的情况下，选择较少数量的信道进行功率分配。在梳状导频信道估计中考虑了最小二乘法 (LS)、最小均方误差 (MMSE) 和最小均方 (LMS) 估计器，而使用 1/2 和 1/3 码率的 turbo 码。从仿真结果来看，对于具有四根天线和八根天线的 MIMO-OFDM 系统，分别观察到 5 b/s/Hz 和 11 b/s/Hz 的容量改进。还发现 LMS 估计器的性能比 LS 提高了 3.5 dB SNR，比 MMSE 提高了 1 dB SNR。本文展示了 LMS 估计器和 1/3 turbo 码如何与 MIMO-OFDM 集成，

更新日期：2021-08-16

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