Interference Coordination via Power Domain Channel Estimation

A novel technique is proposed which enables each transmitter to acquire global channel state information (CSI) from the sole knowledge of individual received signal power measurements, which makes dedicated feedback or inter-transmitter signaling channels unnecessary. To make this possible, we resort to a completely new technique whose key idea is to exploit the transmit power levels as symbols to embed information and the observed interference as a communication channel the transmitters can use to exchange coordination information. Although the used technique allows any kind of {low-rate} information to be exchanged among the transmitters, the focus here is to exchange local CSI. The proposed procedure also comprises a phase which allows local CSI to be estimated. Once an estimate of global CSI is acquired by the transmitters, it can be used to optimize any utility function which depends on it. While algorithms which use the same type of measurements such as the iterative water-filling algorithm (IWFA) implement the sequential best-response dynamics (BRD) applied to individual utilities, here, thanks to the availability of global CSI, the BRD can be applied to the sum-utility. Extensive numerical results show that significant gains can be obtained and, this, by requiring no additional online signaling

A framework for optimal decentralized power control with partial CSI

International audience— In this paper, we use a recent information theoretical result to develop a general framework for finding optimal power control policies in the case of interference channels. The aforementioned result characterizes the achievable payoffs for an N-Agent (transmitters in our application) coordination problem with a certain information structure. We then provide an algorithm which exploits the characterization of achievable payoffs by conditional probability distributions to find optimal decision functions for the transmitters. Due to its general nature, the developed framework is conducive for applications to diverse scenarios in wireless communications. In this article, we restrict our attention to the case of decentralized power control in interference channels for different utility functions namely sum-rate, sum-energy and sum-goodput. Our approach has the following salient features: 1) The method proposes optimal power control functions for any given utility function as opposed to ad-hoc solutions for different utilities proposed in the literature, and 2) Noise in the channel estimation is taken into account, thus providing robust optimal solutions

On the Performance Analysis of Different Selecting Strategies for Type-II Codebook

International audienceThe Type-II codebook is standardized in recent 5G new radio (NR) physical layer release, which supports high resolution channel state information feedback for MIMO transmission. In this paper, we focus on selecting strategies for rank2 Type-II precoder matrix. Firstly, We extend a rank1 solution in the literature to rank2 which is referred to approach1. This approach is subject to its prerequisite which wastes certain feedback bits. To further exploit the feedback bits, we proposed a new selecting strategy, named approach2. Besides, we illustrate that the subband scalar quantization restricted by the standard deteriorates both the orthogonality and the beamforming gains of the rank2 precoder matrices which has varying influence on approaches. Lastly, the simulation results show that the approach2 is more efficient than the approach1 in high and medium correlation channel cases, which is the opposite in the low correlation case

A Novel RIS-Aided EMF-Aware Beamforming Using Directional Spreading, Truncation and Boosting

International audienceThis paper addresses a drawback of massive multiple-input multiple-output Maximum Ratio Transmission beamforming. In some propagation conditions, when the base station serves the same target user equipment for a long period, it reduces the transmit power (and degrades the received power) to avoid creating high exposure regions located in the vicinity of the antenna and concentrated in few directions (corresponding to the best propagation paths between the antenna and the receiver). In this paper, we propose a novel electromagnetic field aware beamforming scheme, which (i) spreads the beamforming radiation pattern in the angular domain by adding artificial propagation paths thanks to reconfigurable intelligent surfaces, (ii) truncates the pattern in strong directions, and (iii) boosts it in weak directions. Compared to existing solutions, it maximizes the received power. However, it also consumes more power. Finally, truncation alone is the best trade-off between received power and energy efficiency, under exposure constrain

A Novel RIS-Aided EMF-Aware Beamforming Using Directional Spreading, Truncation and Boosting

This paper addresses a drawback of massive multiple-input multiple-output Maximum Ratio Transmission beamforming. In some propagation conditions, when the base station serves the same target user equipment for a long period, it reduces the transmit power (and degrades the received power) to avoid creating high exposure regions located in the vicinity of the antenna and concentrated in few directions (corresponding to the best propagation paths between the antenna and the receiver). In this paper, we propose a novel electromagnetic field aware beamforming scheme, which (i) spreads the beamforming radiation pattern in the angular domain by adding artificial propagation paths thanks to reconfigurable intelligent surfaces, (ii) truncates the pattern in strong directions, and (iii) boosts it in weak directions. Compared to existing solutions, it maximizes the received power. However, it also consumes more power. Finally, truncation alone is the best trade-off between received power and energy efficiency, under exposure constrain.Comment: Accepted to 2022 European Conference on Networks and Communications (EuCNC) and the 6G Summit, 7-10 June 2022, Grenoble, France. arXiv admin note: substantial text overlap with arXiv:2206.0687