Browsing by Author "Wavegedara, KCB"

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item: Conference-Extended-Abstract
Co-channel interference mitigation in LTE systems
(2010) Kudavithana, DU; Nishad, IDDT; Rupasinghe, RANP; Ruwanthilake, MAD; Wavegedara, KCB
In emerging Long Term Evolution (LTE) systems, it is expected to reuse the same set of frequency subchannels in each and every cell as much as possible. This will result in high co-channel interference (CI), which degrades the system performance significantly. Hence CI acts as the main performance limiting factor Therefore in order to achieve high system performance, it is imperative to mitigate CI. In this research project we propose a turbo /iterative) receiver architecture, which consists of a soft symbol detector and a soft channel decoder, for the downlink of LTE systems. Moreover, a minimum mean squared error (MMSE) based soft symbol detector is developed to suppress the CI and cancel the co-antenna interference (CAI), which is used in the turbo receiver. In order to improve the performance further, the adaptive fractional frequency reuse (AFFR) coordination scheme is implemented. Using computer simulations, the performance of the proposed receiver is thoroughly investigated for the LTE downlink. The considerable performance improvement achievable using the proposed advanced receiver scheme and its low computational complexity, make it attractive for the implementation in future LTE systems
item: Conference-Extended-Abstract
Transmit beamforming for space-frequency coded MIMO-OFDM cystems operating in a correlated ricean fading channel
(2010) Suraweera, ND; Wavegedara, KCB
In highly spatially-correlated channels the diversity gain obtained by diversity coding schemes (such as Space-frequency (SF) coding or Space-Time (ST) coding) is considerably low. Combining beamforming with SF/ST coding help to improve the system performance in spatially correlated channels. In this paper, we propose two beamforming technique for SF coded MIMO-OFDM systems in a frequence-selective Rician-fading channel to minimize the pair-wise error probability (PEP). The proposed beamforming techniques are based on the channel mean and spatial correlation statistics. In Technique, 1. all the eigenmodes of the channel spatial correlation and mean matrices taken in to consideration, where in Technique 2. Only the strongest egimodes of the channel spatial correlation and mean matrices is considered. Simulation results demonstrate that Technique 2 offers a substantial performance improvement over SF coding without beamforming in highly spatially-correlated channels. Furthermore, considerable performance improvements can be obtained using Technique 1 overSF coding only in low correlated channels with a high Ricean K factor.