On the Optimality of Treating Inter-Cell Interference as Noise in Uplink Cellular Networks

Abstract

In this work, we study the generalized degrees-of-freedom (GDoF) of downlink and uplink cellular networks, modeled as Gaussian interfering broadcast channels (IBC) and Gaussian interfering multiple access channels (IMAC), respectively. We focus on regimes of low inter-cell interference, where single-cell transmission with power control and treating inter-cell interference as noise (mc-TIN) is GDoF optimal. Recent works have identified two relevant regimes in this context: one in which the GDoF region achieved through mc-TIN for both the IBC and IMAC is a convex polyhedron without the need for time-sharing (mc-CTIN regime), and a smaller (sub)regime where mc-TIN is GDoF optimal for both the IBC and IMAC (mc-TIN regime). In this work, we extend the mc-TIN framework to cellular scenarios where channel state information at the transmitters (CSIT) is limited to finite precision. We show that in this case, the GDoF optimality of mc-TIN extends to the entire mc-CTIN regime, where GDoF benefits due to interference alignment (IA) are lost. Our result constitutes yet another successful application of robust outer bounds based on the aligned images (AI) approach.The authors are with the

Toward an Extremal Network Theory—Robust GDoF Gain of Transmitter Cooperation Over TIN

“…Optimal schemes for such GDoF characterizations tend to be naturally robust schemes that require only a coarse knowledge of channel strength 2 parameters α ij at the transmitters. Aided by advances in Aligned Images (AI) bounds [7], GDoF characterizations under finite precision CSIT have been found for a variety of wireless networks in [9][10][11][12][13].The importance of simplicity is reflected in the goal of identifying parameter regimes where simple schemes are optimal in the GDoF sense [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The most relevant examples for our purpose are [14], [15] and [16].…”

“…The importance of simplicity is reflected in the goal of identifying parameter regimes where simple schemes are optimal in the GDoF sense [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The most relevant examples for our purpose are [14], [15] and [16].…”

On Multi-Cell Uplink-Downlink Duality with Treating Inter-Cell Interference as Noise

“…The age-old robust interference management strategy of power control and treating interference as noise (TIN) in wireless networks has recently been given renewed vitality, attracting increasing attention of late [1]- [9]. This revived interest is largely due to the findings of Geng et al [1], who showed that power control and TIN are sufficient to achieve the entire generalized degrees-of-freedom (GDoF) region, and capacity region to within a constant gap, of the K-user Gaussian interference channel (IC) in a broad regime of parameters, described in terms of channel strength levels.…”

“…This revived interest is largely due to the findings of Geng et al [1], who showed that power control and TIN are sufficient to achieve the entire generalized degrees-of-freedom (GDoF) region, and capacity region to within a constant gap, of the K-user Gaussian interference channel (IC) in a broad regime of parameters, described in terms of channel strength levels. The approach and results of Geng et al were generalized and extended in a number of directions reported in [2]- [9].…”

“…The TIN framework of [1] was recently extended to multicell networks in uplink scenarios [9], modeled as the Gaussian interfering multiple access channel (IMAC). TIN is defined in [9] for such setting as the employment of "a MAC-type, capacity-achieving strategy, with Gaussian codebooks and successive decoding....in each cell while treating all inter-cell interference as noise....complemented with power control to manage inter-cell interference".…”