Improved Recursive Algorithms for V-BLAST to Reduce the Complexity and Save Memories

Improvements I-IV were proposed to reduce the computational complexity of the original recursive algorithm for vertical Bell Laboratories layered space-time architecture (VBLAST). The existing recursive algorithm with speed advantage and that with memory saving incorporate Improvements I-IV and only Improvements III-IV into the original algorithm, respectively. To the best of our knowledge, the algorithm with speed advantage and that with memory saving require the lowest complexity and the least memories, respectively, among the existing recursive V-BLAST algorithms. We propose Improvements V and VI to replace Improvements I and II, respectively. Instead of the lemma for inversion of partitioned matrix applied in Improvement I, Improvement V uses another lemma to speed up the matrix inversion step by the factor of 1.67. Then the formulas adopted in our Improvement V are applied to deduce Improvement VI, which includes the improved interference cancellation scheme with memory saving. In the existing algorithm with speed advantage, the proposed algorithm I with speed advantage replaces Improvement I with Improvement V, while the proposed algorithm II with both speed advantage and memory saving replaces Improvements I and II with Improvements V and VI, respectively. Both proposed algorithms speed up the existing algorithm with speed advantage by the factor of 1.3, while the proposed algorithm II achieves the speedup of 1.86 and saves about half memories, compared to the existing algorithm with memory saving.