Abstract—Multiple-Input-Multiple-Output (MIMO) is one of the most important communication techniques that allow wireless systems to achieve higher data rate. To overcome the practical difficulties in implementing Dirty Paper Coding (DPC), various sub- optimal MIMO Broadcast (MIMO-BC) scheduling algorithms are employed which choose the best set of users among all the users. In this paper we discuss such a sub-optimal MIMO-BC scheduling algorithm which employs antenna selection at the receiver side. The channels for the users considered here are not Identical and Independent Distributed (IID) so that users at the receiver side do not get equal opportunity for communication. So we introduce a method of applying weights to channels of the users which are not IID in such a way that each of the users gets equal opportunity for communication. The effect of weights on overall sum-rate achieved by the system has been investigated and presented. Keywords—Antenna selection, Identical and Independent Distributed (IID), Sum-rate capacity, Weighted sum rate. I. INTRODUCTION ULTIPLE-Input Multiple-Output (MIMO) is one of the important communication techniques that allow wireless systems to achieve higher data rate[1]-[3]. Earlier studies have shown that wireless systems can achieve data rate close to fundamental capacity limit using Dirty Paper Coding (DPC) at the base station [4]. However, DPC can be implemented on the ideal assumption of perfect channel state information at the transmitter and it is very complex to implement. There are various scheduling schemes which achieve performance close to fundamental capacity limit for MIMO Broadcast (MIMO-BC) under more practical assumption. The scheduling scheme discussed in [5]-[6] employs simple zero-forcing beam-forming at the transmitter side and an algorithm named as Semi-orthogonal User Selection (SUS) algorithm. Although this algorithm achieves near optimal sum-rate but the amount of feedback required for this scheme Swadhin Kumar Mishra is working as Asst. Proff. in the Department of Electronics and Communication Engineering, Roland Institute of Technology, Berhampur, Orissa, India, Pin: 761008. (phone: +91-9776644121, e-mail: swadhin.mishra@gmail.com). S. Panda is working as Professor in the Department of Electrical and Electronics Engineering, NIST, Berhampur, Orissa, India, Pin: 761008. (e- mail: panda_sidhartha@rediffmail.com ). C. Ardil is with National Academy of Aviation, AZ1045, Baku, Azerbaijan, Bina, 25th km, NAA (e-mail: cemalardil@gmail.com). is very large. In multiuser MIMO systems which have many users at the receiver side, it is advantageous to have full Channel State Information (CSI) at the base station. But providing full CSI to the base station requires huge amount of resources on the uplink channel. Therefore, scheduling schemes based on partial CSI are of great interest. The scheduling scheme discussed in [7] requires partial CSI. However this scheduling scheme results in loss of system throughput. The feedback reduction scheme is described in [8]. In this scheme a threshold is applied on the channel information to reduce the feedback and it is shown that there is not much of reduction of the sum-rate of the system. Opportunity beam-forming is another scheme that is used by systems having partial CSI. In this scheme the transmitter sends random beams to the users and the user which has the highest Signal-to-Noise Ratio (SNR) for each beam is selected [9]. However, none of the receiver processing are considered in the proposed scheme. The amount of feedback is reduced in [10]. The algorithm uses limited feedback. Each of the users at the receiver side selects a pair of transmit and receive antenna which provide the maximum Signal-to-Interference plus Noise Ratio (SINR). For large number of users it is shown that this scheme achieves near optimal sum-rate. It is also shown that by maintaining a threshold on the SINR value, the amount of feedback can significantly be reduced without much loss in the system throughput. The MIMO downlink channels for the users are in general considered as Independent and Identical distributed (IID) Gaussian random channels for ease of computation. But in practical applications many times the channels encountered are not IID. In this paper such a MIMO downlink system is considered in which the downlink channels are not IID. A practical method of generating non-IID users is considered first. The Antenna Selection (AS) algorithm [10] is used for user selection and scheduling. Since the channels for the users are not IID, they behave differently to the transmit signal. Hence each user will not get equal opportunity by the base station for communication. A scheme of applying weights to the channels is considered so that each of the users gets nearly equal opportunity by the base station. Then the effect of applying weights to the channels on the sum-rate of the system is investigated. The weighted sum-rate is compared with the sum-rate achieved by the system without any weights. MIMO Broadcast Scheduling for Weighted Sum-rate Maximization Swadhin Kumar Mishra, Sidhartha Panda, and C. Ardil M International Journal of Electrical and Computer Engineering 4:15 2009 930