Two efficient and low complexity multiuser scheduling algorithms are proposed for the uplink multiple-input multiple-output systems in this paper.Conventionally,the exhaustive search algorithm (ESA) can give the optimal performance; however,it is complexity prohibitive for practical implementation.Aiming at reducing the complexity while keeping the achievable sum rate performance,two heuristic algorithms are proposed for the multiuser scheduling problems:the improved genetic algorithm and simplified norm-based greedy algorithm.Moreover,we also consider the heterogeneity scenario where a modified grouping-based user selection algorithm is given to guarantee the user s fairness.Specifically,the asymptotic behavior of the norm-based greedy algorithm is given when each user is equipped with one antenna.Numerical examples demonstrate the superiority of our proposed scheduling and grouping algorithms.