Experimental and theoretical study of OTA throughput of 4G LTE wireless terminals for different system bandwidths and coherence bandwidths in Rich Isotropic Multipath

Paper i proceeding, 2012

The 3rd Generation Partnership Project (3GPP) has provided successful reports and specifications for Long Term Evolution (LTE) [1]. The LTE standard is the latest communication technology standard today which is extensively adopted by the industry to satisfy the demands of their customers with high speed internet and low latency. The major differences between LTE and its predecessor telecommunication standards i.e. WCDMA and GSM are Orthogonal Frequency Division Multiplexing (OFDM), Multiple-Input Multiple-Output (MIMO), and scalable bandwidth which provide improved receiver sensitivity, higher throughput data-rates, and flexibility. However, LTE also increases cost and system complexity, and therefore it puts strict requirements to ensure as high spectral efficiency as possible. To successfully deploy LTE with improved user-experience, it is of importance to be able to measure, quantify, and compare the performance of LTE devices. This paper presents an experimental study of the effect on the throughput of different system bandwidths when the environment has different coherence bandwidths, for a 2×2 MIMO diversity case. The results are compared with a theoretical model that includes the receiver sensitivity in the form of an ideal threshold receiver as defined in [2]. Both conductive-tests and OTA-tests are performed. The conductive test-environment can be represented by an ideal Line-Of-Sight (LOS) channel (i.e. no fading) with Additive White Gaussian Noise, referred to as an AWGN channel. The OTA test-environment is a Rich Isotropic Multipath (RIMP), i.e. a Rayleigh fading environment with no LOS, emulated experimentally by a reverberation chamber. The Device-Under-Test (DUT) is tested both by connecting a cable directly to an LTE base station simulator, referred to as conducted tests, and in the reverberation chamber. Our previous related work was about conducted and OTA throughput modeling for SISO and SIMO in [2]; for different coherence bandwidths in [3]; and for 2×2 MIMO multiplexing in [4]. The purpose of the present paper is to study measured throughput for different system bandwidths and see how well the OFDM model works for all these, and to investigate how the threshold level change with the system bandwidth.