In this paper, we propose an iterative interference alignment (IA) algorithm for MIMO cellular networks with partial connectivity, which is induced by heterogeneous path losses and spatial correlation. Such systems impose several key technical challenges in the IA algorithm design, namely the overlapping between the direct and interfering links due to the MIMO cellular topology as well as how to exploit the partial connectivity. We shall address these challenges and propose a three stage IA algorithm. As illustration, we analyze the achievable degree of freedom (DoF) of the proposed algorithm for a symmetric partially connected MIMO cellular network. We show that there is significant DoF gain compared with conventional IA algorithms due to partial connectivity. The derived DoF bound is also backward compatible with that achieved on fully connected K-pair MIMO interference channels.

Interference Alignment for Partially Connected MIMO Cellular Networks

Interference alignment (IA) is a promising technique for interference management in wireless networks. However, the sum rate may fall short of the theoretical maximum, particularly at low signal-to-noise ratio (SNR) levels since IA mainly concentrates on mitigating the interference, instead of improving the quality of desired signal. Moreover, most of the previous works focused on improving spectrum efficiency, but the energy efficiency (EE) aspect is largely ignored. In this paper, an adaptive energy-efficient IA algorithm is proposed through power allocation (PA) and transmission-mode adaptation for green IA-based wireless networks. The PA problem for IA is first analyzed; then, we propose a PA scheme that optimizes the EE of IA-based wireless networks. When the SNR is low, the transmitted power of some users may become zero. Thus, the users with low transmitted power are turned into the sleep mode in our scheme to save energy. The transmitted power and transmission mode of the remaining active users are adapted again to further improve the EE of the network. To guarantee the interests of all the users, fairness among users is also considered in the proposed scheme. Simulation results are presented to show the effectiveness of the proposed algorithm in improving the EE of IA-based wireless networks.

/pdf/adaptive-energy-efficient-power-allocation-in-green-3p2ndh1fgd.pdf

Adaptive Energy-Efficient Power Allocation in Green Interference-Alignment-Based Wireless Networks

In this paper, we consider a Partial Interference Alignment and Interference Detection (PIAID) design for K-user quasi-static MIMO interference channels with discrete constellation inputs. Each transmitter has M antennas and transmits L independent data streams to the desired receiver with N receive antennas. We focus on the case where not all K-1 interfering transmitters can be aligned at every receiver. As a result, there will be residual interference at each receiver that cannot be aligned. Each receiver detects and cancels the residual interference based on the constellation map. However, there is a window of unfavorable interference profile at the receiver for Interference Detection (ID). In this paper, we propose a low complexity Partial Interference Alignment scheme in which we dynamically select the user set for IA so as to create a favorable interference profile for ID at each receiver. We first derive the average symbol error rate (SER) by taking into account of the non-Guassian residual interference due to discrete constellation. Using graph theory, we then devise a low complexity user set selection algorithm for the PIAID scheme, which minimizes the asymptotically tight bound for the average end-to-end SER performance. Moreover, we substantially simplify interference detection at the receiver using Semi-Definite Relaxation (SDR) techniques. It is shown that the SER performance of the proposed PIAID scheme has significant gain compared with various conventional baseline solutions.

Partial Interference Alignment for $K$ -User MIMO Interference Channels

In general, techniques are described for performing an interpolation with respect to decomposed versions of a sound field. A device comprising one or more processors may be configured to perform the techniques. The processors may be configured to obtain decomposed interpolated spherical harmonic coefficients for a time segment by, at least in part, performing an interpolation with respect to a first decomposition of a first plurality of spherical harmonic coefficients and a second decomposition of a second plurality of spherical harmonic coefficients.

Interpolation for decomposed representations of a sound field

In general, techniques are described for transitioning an ambient higher order ambisonic coefficient. A device comprising a memory and a processor may be configured to perform the techniques. The processor may obtain, from a frame of a bitstream of encoded audio data, a bit indicative of a reduced vector. The reduced vector may represent, at least in part, a spatial component of a sound field. The processor may also obtain, from the frame, a bit indicative of a transition of an ambient higher-order ambisonic coefficient. The ambient higher-order ambisonic coefficient may represent, at least in part, an ambient component of the sound field. The reduced vector may include a vector element associated with the ambient higher-order ambisonic coefficient in transition. The memory may be configured to store the frame of the bitstream.

Transitioning of ambient higher-order ambisonic coefficients

Embodiments of the present invention provide a method for feeding back channel state information, and a method and a device for obtaining channel state information. The method for feeding back the channel state information includes: compressing, by a user equipment, original time domain channel state information to obtain compressed time domain channel state information; quantizing the compressed time domain channel state information to obtain a codebook index; and sending the codebook index to a base station. With the technical solutions provided by the embodiments of the present invention, the total overhead used for feeding back the channel state information from the user equipment to the base station is reduced.

Method for feeding back channel state information, and method and device for obtaining channel state information

A data transmission method, a communications system and related apparatuses are disclosed. The data transmission method includes the following steps: a transmitter obtains channel information corresponding to channels between the transmitter and several receivers; the transmitter obtains a control vector corresponding to a receiver according to the channel information; the transmitter modulates data to be transmitted by means of one-dimensional modulation to obtain modulated symbols; the transmitter processes the modulated symbols and the control vector to obtain transmitted data of each antenna; the transmitter transmits the transmitted data to the receiver; the receiver receives the transmitted data in a predetermined spatial direction of received symbol. The present invention also discloses a communications system and related apparatuses.

Method and system for data transmission

Channel state information feedback method, channel state information acquisition method and equipment

In this paper, we propose a novel interference alignment (IA) scheme via convex optimization based on minimum mean square error criterion subject to individual transmit power constraints for the MIMO interference channel system We show that transceiver under such criterion can be realized through an efficient iterative algorithm The convergence of the proposed algorithm is discussed Simulation results show that the proposed scheme outperforms the existing IA schemes with fast convergence

A Novel Iterative Interference Alignment Scheme via Convex Optimization for the MIMO Interference Channel

The invention discloses a resource distribution method and a resource distribution device for a multi-relay orthogonal frequency division multiplexing system. The resource distribution method for the multi-relay orthogonal frequency division multiplexing system comprises the following steps: acquiring actual channel information, and acquiring a resource distribution parameter according to actual channel information-based mathematical optimization problem, wherein the resource distribution parameter comprises at least two of subcarrier power distribution, relay selection and subcarrier pairing, and the mathematical optimization problem is set for the subcarrier power distribution, relay selection and subcarrier pairing on the basis of channel information by utilizing end-to-end transmission rate optimization principle; and transmitting signals according to the resource distribution parameter. The technical scheme optimizes the system performance.

Resource distribution method and device for two-hop multi-relay orthogonal frequency division multiplexing system

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