International Journal of Computer Applications (0975 – 8887) Volume 64– No.7, February 2013 7 Interference Cancellation using Logic OR Operation in MIMO Receiver Md. Abdul Latif Sarker Dept. of Electronic Engineering, Chonbuk National University, Jeonju-City, 561-756, Republic of Korea Moon Ho Lee Dept. of Electronic Engineering, Chonbuk National University, Jeonju-City, 561-756, Republic of Korea ABSTRACT Lately, interference cancellation is a hard challenge in a cellular communication system. In this paper, we consider the interference cancellation using logic OR gate from the multiple input multiple output (MIMO) interference channel where each transmitter and receiver equipped with single or multiple antennas. In our system, we have used a threshold logic unit which is operated by logic OR with NOT operation in the MIMO receiver for interference cancellation. The threshold unit has two logic threshold signals which are separated by two vectors. These two logic thresholds are denoted by High and Low signal in the threshold unit. The High and Low signals are represented by the desired and interference signal, respectively. Our approach is to practically achieve interference alignment and absolutely cancel to the interference from the received signal by using logic OR operation in the MIMO receiver. General Terms Interference, MIMO transmitter and receiver, logic OR and NOT operation, threshold unit. Keywords System model; interference alignment; interference cancellation using logic OR gate operation. 1. INTRODUCTION 3rd Generation Partnership Project (3GPP) started work on LTE is illustrated in Release 7, 2005 [1]. It is also called as Evolved-Universal Mobile Telecommunication System Terrestrial Radio Access (E-UTRA) and known as 4th Generation (4G) of mobile radio technologies which is increasing the spectral efficiency, peak data rate, higher throughput. The Coordinated multi-Point transmission system is an essential technology for 4th generation (4G) cellular system [2] and [3]. This technique can interrupt the intra-cell, the inter-cell inference and improve the cell edge throughput [4]. For downlink, the CoMP transmission is mainly two categories: joint processing (JP) and coordinated scheduling/beamforming (CS/CB) [5]. The transmitter has entire channel state information (CSI) and then done pre- coding. In practical wireless communication system, base station location is stable but the used equipment (UE) safely moving and the resulting CSI characteristic is varying quickly in an indefinite behavior. At that time the complete CSI tracks at the transmitter and receiver sides are very difficult. More research work is founded for the purpose of enhancing the system capacity, increase the spectral efficiency, bit-error-rate performance and increase the cell-edge throughput etc. At present, the improvement in the study of interference channels various types of power tools involved in the study of general wireless networks have founded. Interference alignment and cancellation is the one of them. The main feature of the cellular system is interference which remaining to the broadcast behavior of wireless links. For multi-user detection, there are two types of interference in mobile communication such that very strong interference [8] and weak interference. For weak interference, the interfering signal is conducted as noise and single user encoding/decoding suffices. For strong interference, the efficient to the desired signal, then interference is avoided by orthogonalzing the channel access. In this paper we will align and cancel the interference by logic OR gate operation in the MIMO receiver. This paper is described as below: Section 2 gives an overview of the system model and section 3 is narrated the interference alignment, respectively. The interference cancellation using OR gate operation is given in section 4. Finally, simulation results and conclusions are presented in section 5. 2. SYSTEM MODEL In this section, we describe the system model for the interference channel. Suppose, K-user MIMO interference channel with j transmitter receiver pairs and kj H be a k j N M  matrix where the channels gain from transmitter j and receiver k , respectively. The random vectors 1 j M  for j x , the received signal at the receiver k is given by from Fig 1 and [6], int K H H k kk k k kj j j k j k noise Desired Signal erference signal y H Fs H Fs n      (1) where k y is the 1 k N  output vector at receiver k , H kk k k H Fs is the desired signal and K H kj j j j k H Fs   is the interference signal which is coming from the interference channel. j s is a 1 j M  random vector that denotes the transmitted signal of user j and   ~ 0,1 k n N is a zero means Additive White Gaussian Noise (AWGN). Consider a beamforming matrix k F to send the signal vector k s to its intended receiver k . At the receiver side, the receiver k , estimates the transmitted data vector k s by using a linear beamforming matrix k U ,