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This paper tackles the problem of multi-user in- terference in the forward downlink channel of a multi-beam satellite system. A symbol-level precoding scheme is considered, where the data information is used, along with the channel state information, in order to exploit the multi-user interference and transform it into useful power at the receiver side. In this frame- work, the max-min fair problem...
In this paper, we propose a hybrid precoding scheme utilizing traditional linear precoding methods to achieve approximate optimal performance with low complexity. The proposed scheme implements phase control using linear precoding methods at the analog precoding domain and employs the same linear precoding method in the digital domain to maintain the antenna gain. We simulate our proposed schemes...
High throughput satellites rely on the reuse of spectrum across different beams. To this end, beams are synthesized by complex array fed reflectors. Multiuser techniques such as precoding can make viable an aggressive reuse of the spectrum, even to the point of facilitating the path towards full frequency reuse deployments. This entails a high demand on the feeder link, which needs to be provisioned...
Non-orthogonal multiple access (NOMA) is an emerging technology that can improve system spectral efficiency. In this paper, we propose a downlink multiple-input-multiple- output (MIMO) wireless system that incorporates NOMA. To make the system model more realistic, error propagation in successive interference cancellation (SIC) is considered during the decoding process. We formulate an optimization...
In this paper, we first consider a downlink multiple- input multiple-output non-orthogonal multiple access (MIMO-NOMA) system with a base station and four users, where the users are equally divided into two clusters and inter-cluster interference is induced in transmission. Then we propose a joint clustering and precoding algorithm for the system such that not only the inter-cluster interference can...
Ultra dense network (UDN) is identified as one of the key enablers for 5G since it can provide ultra high spectral reuse factor exploiting proximal transmissions. By densifying the network infrastructure equipments, it's highly possible that each user will have one or more dedicated serving base station antennas, introducing the user-centric virtual cell paradigm. However, due to irregular deployment...
We propose a transmit preprocessing aided spatial modulation (PSM) scheme for downlink of multi-user multiple-input multiple-output (MIMO) systems which exploits the spatial correlation matrices of users. In this way, array antennas in base station can be scaled to large dimensions while requiring reduced dimension channel state information at transmitter (CSIT). This property makes proposed PSM suitable...
In this paper, we investigate the physical layer security scheme in heterogeneous Device-to-Device (D2D) and cellular networks. More specifically, we aim to optimize the secrecy capacity of D2D users in a single cell where the D2D users share downlink resource with cellular users. We assume that base station is equipped with multiple antennas while other nodes are equipped with single antenna, and...
Broadband power line communication (BPLC) is a promising technology for indoor broadband communication networks. However, BPLC has restricted transmission power in the very high frequency (VHF) band in order to avoid harmful interference to existing wireless services. In this paper, a new hybrid multiple-input multiple-output (MIMO) system is proposed between BPLC and TV white space (TVWS) channels...
We propose a decentralized algorithm for weighted sum rate (WSR) maximization via large system analysis. The rate maximization problem is done via weighted sum mean-squared error (WSMSE) minimization. Decentralized processing relies on the exchange via a backhaul link of a low amount of information. The inter-cell interference terms couple the maximization problems at the different base stations (BS)s...
It is a open research problem of great interest how to fully utilize the benefits of massive MIMO original designed for Time Division Duplex (TDD) also in Frequency-Division Duplexing (FDD). For efficient multi-user downlink transmission Channel State Information (CSI) has to be obtained at the receiver side and fed back to the transmitter. Due to signaling/pilot overhead scaling with the number of...
In order to meet the ever increasing mobile application proliferation and data traffic growth, next-generation wireless networks or 5G networks are under a revolutionary technology innovation path towards these goals. In this paper, we introduce a hybrid MU-MIMO and NOMA design scheme in wireless heterogeneous networks to improve the system throughput and also to increase multi-user diversity gains...
Massive MIMO (multiple-input multiple-output) is a promising technology for the upcoming 5G as it provides significant beamforming gains and interference reduction capabilities due to the large number of antennas. However, massive MIMO is computationally demanding, as the high antenna count results in high-dimensional matrix operations when conventional MIMO processing is applied. In this paper, we...
Massive MIMO is a promising technology for the 5G mobile communications system and contributes to the enhancement of multi-user MIMO transmission. However, the user scheduling of multi-user MIMO transmission requires a high computational complexity because the matrix operation is performed to estimate SINR, which is used as a user selection criterion. In this paper, we investigate low complexity multi-user...
For general MIMO relay AF networks, transmitting different number of data streams lead to significantly different performances. Therefore stream selection is an important preprocessing to maximize the sum rate. We first show that the problem to select only one stream for networks with single antenna users is NP-hard. Then based on the Total Signal to Total Interference plus Noise Ratio model, the...
For a massive multiple-input-multiple-output (MIMO) system operated under frequency-division duplex (FDD), downlink training was usually considered impractical due to huge amount of pilot signals and feedback overhead. Although some efforts have been spent to reduce such an overhead in recent works, the reduction is still limited. More recently, some precoding methods that do not require downlink...
This work focuses on large scale multi-user MIMO systems in which the base station (BS) outfitted with M antennas communicates with K single antenna user equipments (UEs). In particular, we aim at designing the linear precoder and receiver that maximizes the minimum signal-to-interference-plus-noise ratio (SINR) subject to a given power constraint. To gain insights into the structure of the optimal...
In this paper we study the downlink of a hybrid analog-digital massive multi-user MIMO (MU-MIMO) system. An efficient hybrid strategy is proposed, where the analog beamforming matrices are determined using a channel matching criterion while the digital beamforming consists of pre-filters and post-filters. The digital post-filters are computed using traditional linear MU-MIMO strategies together with...
Millimeter wave (mmWave) systems will likely employ large antenna arrays at both the transmitters and receivers. A natural application of antenna arrays is simultaneous transmission to multiple user equipments (UEs), which requires multi-user precoding at the transmitter. However, hardware constraints and operation loads make it challenging to apply conventional pure MIMO digital precoding or even...
For single-cell multi-user massive multi-input-multi-output (MIMO) system downlink, we consider the per-antenna power constraint and propose a modified maximum-ratio-transmission (MRT) precoding scheme. The outage probability performance of the scheme are analyzed. To enable the analysis, we study the random behaviour of the signal-to-interference-plus-noise-ratio (SINR) and derive an approximation...
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