Incremental Lattice Reduction: Motivation, Theory, and Practical Implementation

For multiple-input multiple-output communication systems that employ four or more transmit and four or more receive antennas, symbol detection remains a challenge in communication systems research. Lattice-reduction-aided detectors are attractive solutions to this problem because these detectors achieve the same diversity as the maximum-likelihood detector while exhibiting lower complexity. Current applications of lattice-reduction-aided detectors involve executing a lattice reduction algorithm to completion and then utilizing this result in the subsequent symbol detection. In this article, however, we examine the possibility of partially executing the lattice reduction algorithm. We first demonstrate using a hypothetical lattice-reduction-aided detector that early termination of lattice reduction algorithms is possible in the context of MIMO detection. Encouraged by these results, we develop and introduce incremental lattice reduction, which utilizes a practical early termination condition. We then apply this idea to develop a joint symbol detection and lattice reduction algorithm that is based on the Lenstra, Lenstra, Lovasz algorithm and successive interference cancellation. An evaluation using a spatial correlation channel model demonstrates that the proposed algorithm effectively distributes the lattice reduction processing over the length of each received packet. This behavior naturally enables the relaxation of throughput and latency requirements of lattice reduction algorithm hardware realizations.