MIMO Wireless Communications - From Real-World Propagation to Space-Time Code Design, Oestges and Clerckx Oestges & Clerckx.pdf (original) (raw)

MIMO channels: optimizing throughput and reducing outage by increasing multiplexing gain

TELKOMNIKA Telecommunication Computing Electronics and Control, 2020

The two main aims of deploying multiple input multiple out (MIMO) are to achieve spatial diversity (improves channel reliability) and spatial multiplexing (increase data throughput). Achieving both in a given system is impossible for now, and a trade-off has to be reached as they may be conflicting objectives. The basic concept of multiplexing: divide (multiplex) transmit a data stream several branches and transmit via several (independent) channels. In this paper, we focused mainly on achieving spatial multiplexing by modeling the channel using the diagonal Bell Labs space time scheme (D-BLAST) and the vertical Bell Labs space time architecture (V-BLAST) Matlab simulations results were a lso given to further compare the advantages of spatial multiplexing. Keywords: Diversity MIMO Multiplexing Reliability Spatial Throughput This is an open access article under the CC BY-SA license. 1. INTRODUCTION The need for and data rates and a high quality of service (QoS). Over the years, the ubiquity offered by wireless communication has made it the more preferred means over wired; hence, there has been an increase in research on how to improve the modulation schemes used over the air interface. Multiple input multiple output (MIMO) offers desirable properties that meet most of the requirement stated above. By using multiple output multiple input (MIMO) systems, diversity gain mitigates fading, increases coverage and improves QoS. Multiplexing gain increases capacity and spectral efficiency with no additional power or bandwidth expenditure [1]. The core idea under the MIMO systems is the ability to turn multi-path propagation, which is typically an obstacle in conventional wireless communication, into a benefit for users [2]. With MIMO, the capacity of a communication system increases linearly with the number of antennas, thereby achieving an increase in spectral efficiency, without requiring more resources in terms of bandwidth and power [3-5]. From Figure 1 shows that MIMO technology has two main objectives which it aims to achieve: high spatial multiplexing gain and high spatial diversity. To attain spatial multiplexing, the system is made to carry multiple data stream over one frequency, simultaneously-form multiple independent links (on same channel) between transmitter and receiver to communicate at higher data rates. In low SNR environment, spatial diversity techniques are applied to mitigate fading and the performance gain is typically expressed as diversity gain (in dB) [6]; for higher SNR facilitates the use of spatial multiplexing (SM), i.e., the transmission of parallel data streams, and information theoretic capacity in bits per second per Hertz (bits/s/Hz) is the performance measure of choice [7]. Spatial diversity works on the principle of transmission