Implementation of a MIMO OFDM-Based Wireless LAN System

Abstract

Abstract-The combination of multiple-input multiple-output (MIMO) signal processing with orthogonal frequency division multiplexing (OFDM) is regarded as a promising solution for enhancing the data rates of next-generation wireless communication systems operating in frequency-selective fading environments. To realize this extension of OFDM with MIMO, a number of changes are required in the baseband signal processing. An overview is given of the necessary changes, including time and frequency synchronization, channel estimation, synchronization tracking, and MIMO detection. As a test case, the OFDM-based wireless local area network (WLAN) standard IEEE 802.11a is considered, but the results are applicable more generally. The complete MIMO OFDM processing is implemented in a system with three transmit and three receive antennas, and its performance is evaluated with both simulations and experimental test results. Results from measurements with this MIMO OFDM system in a typical office environment show, on average, a doubling of the system throughput, compared with a single antenna OFDM system. An average expected tripling of the throughput was most likely not achieved due to coupling between the transmitter and receiver branches.Index Terms-MIMO systems, orthogonal frequency division multiplexing (OFDM), space division multiplexing, synchronization, wireless LAN.

An Adaptive Power and Bit Allocation Algorithm for MIMO OFDM/SDMA System Employing Zero-Forcing Multi-user Detection

“…It includes N R antennas and data processing blocks whose functions are similar to those in the transmitter of Fig.1. Assuming perfect frequency synchronization, time synchronization and availability of tracking pilot subcarrier [24], the received signals of mth subcarrier is expressed as (2). In the undertaken investigations, it is assumed that the CSI is perfectly known to the receiver.…”

Review of MIMO-OFDM using Carrier Offset on behalf of Literature Survey

“…The maturing of MIMO OFDM technology leads to a several applications such as digital video broad casting (DVB), digital audio broadcasting (DAB), the IEEE 802.16a wireless metropolitan area network (WMAN) standard, and IEEE 802.11a wireless local area network (WLAN) standard. OFDM is also used for dedicated short-range communications and as a potential candidate for fourth generation (4G) mobile wireless communication systems [2]. In MIMO OFDM a collection of problems including carrier frequency offset (CFO), channel distortion and I/Q (in phase quadrature) imbalance can seriously degrade the system performance.…”

Performance Analysis of Zero-IF MIMO OFDM Transceivers with IQ Imbalance

“…The advantages of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO OFDM) as basis for next-generation high data-rate broadband wireless systems have been reported in many publications over the last few years [2][3][4]. Many challenges, however, remain in the efficient and low-cost implementation of these kind of systems, especially since they involve multiple radio front-ends.…”