Abstract: An Ordered Reduced Set Successive Detector (RSSD) for the V-BLAST spatial multiplexing scheme that uses a general two-dimensional non-uniform set partitioning for different symbols. The detector provides improved diversity and SNR gains at reduced complexity compared to a uniform set partitioning based detector. The detector can be used to reduce the complexity, with a small tradeoff in performance. Further, it is possible to obtain a quasi-ML performance using the disclosed detector at a reduced, yet fixed, complexity.

Abstract: Present robust 2D-MMSE or minimax approach assumes significant time and frequency selectivity due to which it has a poor MSE performance for RBs with low/moderate frequency and/or time selectivity. Further, a filter cannot be designed assuming low frequency and/or time selectivity and use that for all channel models. The instant invention proposes Robust Adaptive (RA) MMSE filter that can bridge the gap between a robust 2D-MMSE/minimax and the optimal MMSE approach. Further, the RA-MMSE filter smoothens the filter coefficients of the robust 2D-MMSE filter with the degree of smoothing adaptively changing with amount of frequency and time selectivity within a RB. Further, the method uses multiple hypothesis tests on the maximum likelihood CFR estimates at the pilots. Further the RA-MMSE filter solves the minimax estimation problem with additional constraints on the autocorrelation sequence corresponding to the channel frequency response.

Abstract: Embodiments herein provide using extreme value theory (EVT) as a diagnostic to decide which taps are significant. In the low SINR scenario, embodiments herein also provide the following options; i) Fix the model order to a finite value smaller than the model order assumed for the initial CIR estimate. In the case of OFDM based systems, the model order of the CIR is fixed to a value much smaller that the cyclic prefix length. ii) Use the EVT based method to detect significant tap locations and only keep those tap locations such that the CIR length is again restricted to a value smaller than the model order of the initial channel estimate.

Abstract: Cognitive interference management in Cellular wireless network with relays and micro/pico/femto cells operated in distributed scheduling mode. A cellular system may use RS to improve capacity or for coverage extension. A RS relays the signals between BS 104 and MS by using wireless links between BS-RS and RS-MS during both downlink and uplink transmissions. Embodiments herein disclose a mechanism to explicitly indicate to the MS whether the MAC management messages sent by the BS to the MS are to inform it to perform scanning for interference measurement. Also, disclosed herein is a mechanism to explicitly indicate to the BS whether the message sent by the MS is related to interference measurement.

Abstract: Embodiments disclosed herein reduce interference at pilot symbols and also enable good interference measurements by using a combination pilot tones and null tones along with null tones. In this type of system, the receivers can estimate tile channel state information without any interference from the remaining transmitters and at the same time the receiver can measure either the individual interference channel states or the interference covariances from the silent periods. The groups of transmitters are reused in geographically separated region using a frequency reuse structure. In a preferred implementation, pilot signal is precoded using a multi-antenna precoder. The precoder may be same for pilot and data.

Abstract: Precoding for multiple transmission streams in multiple antenna systems. Embodiments herein disclose a general method that transmits signal from multiple antennas using a one/two dimensional precoder followed by STBC/SFBC or SM encoder. This precoder is fixed in a given resource block (RB) or slot, which is composed of P subcarriers and Q OFDM symbols (where the values for P and Q are greater than or 5 equal to 1). The precoder in each resource block may take same or different values, which span the two dimensional time-frequency grid. The precoder is chosen as a function of either logical frequency index or physical frequency index of the RB.

Abstract: Embodiments herein provide methods and systems for enhancing interference mitigation using conjugate symbol repetition and phase randomization on a set of subcarriers. The repeated data tone in the signal is complex-conjugated before transmission, when the repetition factor is two. When the repetition factor is greater than two, a combination of conjugate repetition and random/deterministic phase variation of the repeated tones is used to mitigate the interference mitigation. Embodiments further disclose Collision Free Interlaced Pilot PRU Structures that can be used with or without conjugate symbol repetition and phase randomization for interference mitigation.