Linear signal process for MIMO system is prefer to non-linear one due to computational complexity. If transmitter can be fed back right-unitary-matrix by Singular value decomposition from receiver, channel-capacity can be achieved with linear processes in point to point wireless MIMO communication. However, if transmitter can not be fed back right-unitary-matrix from receiver (no-feedback), the optimal linear detector at receiver is minimum-mean-variance-estimator, of which capacity is far from channel-capacity. In first part of this paper, we propose the limited feedback system for linear process. The proposed scheme has near-channel-capacity, while the amount of feedback information is only integer matrix, which is much less than that of right-unitary-matrix via SVD. The key ideas of proposed scheme are Lattice reduction and modulo operation. Further, we minimize the amount of feedback information as binary matrix with multi-level/multi-stage encode and decode. In second part of this paper, we propose two-stage decoding with lattice reduction aided linear detection in multiuser uplink system. Since channel feedback is hard to be expected in uplink system, receiver side equalization is important. In communication applications, these processing techniques can be broadly categorized into two classes, linear and non-linear approaches, which have a trade-off between complexity and performance. Complexity of the proposed scheme for approximated posteriori probabilities of received symbols, can be reduced as much as that of Zero-forcing, approaching a near performance of Maximum likelihood detection. We consider powerful turbo channel codes and show that excellent performance at very high data rates. We compare our simulation results with Shannon capacity limits for ergodic multiple-antenna channel.
본 논문에서는 차세대 무선 통신 솔루션으로 제시되고 있는 coded MIMO 시스템에서의 저복잡도, 고성능을 만족시키는 검파 및 복호 기법을 제시하였다.
기존 MIMO 무선 통신은 고성능에 도달하기 위해 비선형 검파 기법이 가미된 복호 기법과 구현 복잡도를 낮추기 위한 선형 검파 기법이 가미된 복호 기법으로 분리되 연구되어 왔다.
본 논문에서는 격자 축소 기법과 linearity를 가지는 체널 코드의 성질을 복합적으로 이용하기 위해, modulo를 적용한 기법을 제시하였다. 본 기법은 신호의 검파 및 복호를 복합적으로 수행하는 기법으로써, 무선 통신의 가장 기본적인 두 가지 명제인 저복잡도와 고성능 모두를 만족시키게 된다.
성능 평가를 위해 실제 통신 환경에서 사용되는 강력한 체널 코드를 적용하여 다양한 모의 실험을 수행하였다.
