Degrees of Freedom of the Three-User Rank-Deficient MIMO Interference Channel

作者：Zeng Yong^*; Xu Xiaoli; Guan Yong Liang; Gunawan Erry; Wang Chenwei

来源：IEEE Transactions on Wireless Communications, 2014, 13(8): 4179-4192.

DOI：10.1109/TWC.2014.2315037

• Degrees of freedom (DoF)
• multiple-input-multiple-output (MIMO) interference channel (IC)
• rank deficiency
• zero forcing
• interference alignment

We provide the degrees of freedom (DoF) characterization for the three-user M-T x M-R multiple-input-multiple-output (MIMO) interference channel (IC) with rank-deficient channel matrices, where each transmitter is equipped with M-T antennas and each receiver with M-R antennas, and the interfering channel matrices from each transmitter to the other two receivers are of ranks D-1 and D-2, respectively. One important intermediate step for both the converse and achievability arguments is to convert the fully-connected rank-deficient channel into an equivalent partially-connected full-rank MIMO-IC by invertible linear transformations. As such, existing techniques developed for full-rank MIMO-IC can be incorporated to derive the DoF outer and inner bounds for the rank-deficient case. Our result shows that when the interfering links are weak in terms of the channel ranks, i.e., D1 + D2 <= min(M-T, M-R), zero forcing is sufficient to achieve the optimal DoF. On the other hand, when D-1 + D-2 > min(M-T, M-R), a combination of zero forcing and interference alignment is in general required for DoF optimality. The DoF characterization obtained in this paper unifies several existing results in the literature.

• 出版日期2014-8