Abstract
Consider a K-user flat fading MIMO interference channel where the kth transmitter (or receiver) is equipped with M k (respectively N k) antennas. If an exponential (in K) number of generic channel extensions are used either across time or frequency, Cadambe and Jafar showed that the total achievable degrees of freedom (DoF) can be maximized via interference alignment, resulting in a total DoF that grows linearly with K even if M k and N k are bounded. In this work we consider the case where no channel extension is allowed, and establish a general condition that must be satisfied by any degrees of freedom tuple (d 1,d 2,⋯,d K) achievable through linear interference alignment. For a symmetric system with M k=M, N k=N, d k=d for all k, this condition implies that the total achievable DoF cannot grow linearly with K, and is in fact no more than K(M+N)/(K+1). We also show that this bound is tight when the number of antennas at each transceiver is divisible by d, the number of data streams per user.
| Original language | English (US) |
|---|---|
| Article number | 6061974 |
| Pages (from-to) | 812-821 |
| Number of pages | 10 |
| Journal | IEEE Transactions on Signal Processing |
| Volume | 60 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 2012 |
Bibliographical note
Funding Information:Manuscript received April 18, 2011; revised August 19, 2011; accepted September 27, 2011. Date of publication October 26, 2011; date of current version January 13, 2012. The associate editor coordinating the review of this manuscript and approving it for publication was Dr. Mathini Sellathurai. This work was supported in part by the Army Research Office, grant number W911NF-09-1-0279, and in part by a research gift from Huawei Technologies Inc.
Keywords
- Algebraic geometry
- MIMO interference channel
- interference alignment