TY - JOUR

T1 - Degrees of freedom of interference channels with CoMP transmission and reception

AU - Annapureddy, V. Sreekanth

AU - El Gamal, Aly

AU - Veeravalli, Venugopal V.

N1 - Funding Information:
Manuscript received September 25, 2011; revised March 26, 2012; accepted April 20, 2012. Date of publication May 09, 2012; date of current version August 14, 2012. This work was supported in part by the National Science Foundation Award CCF-0904619, through the University of Illinois at Urbana-Champaign, and in part by grants from Intel and Motorola Solutions. This paper was presented in part at the 2010 IEEE International Symposium on Information Theory.

PY - 2012

Y1 - 2012

N2 - We study the degrees of freedom (DoF) of the K-user interference channel with coordinated multipoint (CoMP) transmission and reception. Each message is jointly transmitted by M t successive transmitters, and is jointly received by M r successive receivers. We refer to this channel as the CoMP channel with a transmit cooperation order of M t and receive cooperation order of M r. Since the channel has a total of K transmit antennas and K receive antennas, the maximum possible DoF is equal to K. We show that the CoMP channel has K DoF if and only if M t + M r ≥ K+1. The key idea is that the zero forcing of the interference corresponding to the ith message at the decoder of the jth message, where j ≠ i, can be viewed as a shared responsibility between the M t transmitters carrying the ith message, and the M r receivers decoding the jth message. For the general case, we derive an outer bound that states that the DoF is bounded above by ⌈(K + M t + M r - 2)/2⌉. For the special case with only CoMP transmission, i.e, M r = 1, we propose a scheme that can achieve (K+M t-1)/2 DoF for all K < 10, and conjecture that the result holds true for all K. In the proposed coding scheme, the M t transmitters carrying each message are used to cancel the interference introduced by this message at the first M t-1 receivers, thereby allowing each of these receivers to enjoy 1 DoF, and asymptotic interference alignment is used to align the interfering signals at each other receiver to occupy half the signal space. The achievability proofs are based on the notion of algebraic independence from algebraic geometry.

AB - We study the degrees of freedom (DoF) of the K-user interference channel with coordinated multipoint (CoMP) transmission and reception. Each message is jointly transmitted by M t successive transmitters, and is jointly received by M r successive receivers. We refer to this channel as the CoMP channel with a transmit cooperation order of M t and receive cooperation order of M r. Since the channel has a total of K transmit antennas and K receive antennas, the maximum possible DoF is equal to K. We show that the CoMP channel has K DoF if and only if M t + M r ≥ K+1. The key idea is that the zero forcing of the interference corresponding to the ith message at the decoder of the jth message, where j ≠ i, can be viewed as a shared responsibility between the M t transmitters carrying the ith message, and the M r receivers decoding the jth message. For the general case, we derive an outer bound that states that the DoF is bounded above by ⌈(K + M t + M r - 2)/2⌉. For the special case with only CoMP transmission, i.e, M r = 1, we propose a scheme that can achieve (K+M t-1)/2 DoF for all K < 10, and conjecture that the result holds true for all K. In the proposed coding scheme, the M t transmitters carrying each message are used to cancel the interference introduced by this message at the first M t-1 receivers, thereby allowing each of these receivers to enjoy 1 DoF, and asymptotic interference alignment is used to align the interfering signals at each other receiver to occupy half the signal space. The achievability proofs are based on the notion of algebraic independence from algebraic geometry.

KW - Algebraic independence

KW - Jacobian criterion

KW - coordinated multipoint (CoMP)

KW - interference alignment

KW - partial cooperation

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U2 - 10.1109/TIT.2012.2198614

DO - 10.1109/TIT.2012.2198614

M3 - Article

AN - SCOPUS:84865398744

SN - 0018-9448

VL - 58

SP - 5740

EP - 5760

JO - IEEE Transactions on Information Theory

JF - IEEE Transactions on Information Theory

IS - 9

M1 - 6197715

ER -