A Simple and Efficient IQ Data Compression Method Based on Latency, EVM, and Compression Ratio Analysis

Abstract

Latency, error vector magnitude (EVM) and compression ratio (CR) are performance evaluation factors of IQ data compression. The purposes of IQ data compression are to minimize the latency, EVM and to maximize the CR. However, there is a tradeoff between them. In this paper, based on the evaluation factors, we analyze existing IQ data compression schemes and propose a simple and efficient method from the analyzed results. The proposed method is composed of partial cyclic prefix and cyclic suffix insertion, K/L decimation, low-order bits removal, and partial Huffman code. It presents the techniques to minimize the EVM caused by K/L decimation and to optimize the number of removable low bits and available Huffman encoding bits based on the average signal power and desired EVM. The proposed method can achieve the CR of 4 times or more in about 2% EVM for the LTE downlink and uplink. The simulation results show that the proposed method is applicable to SIMO and MIMO environments.

Keywords

• IQ data compression
• latency
• error vector magnitude (EVM)
• Huffman code