Keyhole and Correlation Effects
Trung Q. Duong, Raj S. Mahat, and R. Dhakal
Abstract—The main purpose of this paper is to derive closed form analytical expressions of symbol error rate (SER) of Mary phase shift keying (MPSK) for MIMO decode-and forward
(DF) relay system. Based on moment generating function (MGF) of output symbol to noise ratio (SNR) of overall system SER is derived. In this paper, we consider an nt -antenna at the source S, an nr -antenna at the relay R and nd -antenna at the destination
D, where the propagated signal from the source passes through keyhole and correlated channel. The same orthogonal space time block codes (OSTBC) is applied to source -destination, sourcerelay and relay-destination link to exploit the maximal diversity gain. Furthermore, we analyze the effects of MPSK modulation on MIMO DF system under different values of correlation coefficient by combining the different antenna pairs at different nodes. Beside this, we compare keyhole and no keyhole MIMO relay systems with fix value of correlation coefficient and antenna pairs. With the use of cooperative scheme, effects of keyhole on MIMO DF architecture can be minimized to certain level.
Eventually, our simulation analysis have excellent match with analytical results, which is sufficient to validate our work.
Index Terms—Correlated channel, decode-and-forward, keyhole effects, moment generating function, orthogonal space-time block codes, symbol error rate.
I. I NTRODUCTION
It has been known that use of multiple antennas at transmitter and receiver increases speed of data transmission between communication terminals. However, MIMO channel capacity is degraded by correlation and keyhole effects. Because of the keyhole effect [1], [2], the rank of MIMO channel matrix is reduced to one, even in the absence of antenna correlation.
In a keyhole affected MIMO channel, signals have to pass through keyhole