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A required feature for the next generation of wireless communication networks will be the capability to serve simultaneously a large number of devices with heterogeneous CSIT qualities and demands. In this paper, we consider the overloaded MISO BC with two groups of CSIT qualities. We propose a transmission scheme where degraded symbols are superimposed on top of spatially-multiplexed symbols. The...
Cell-Free Massive MIMO comprises a large number of distributed single-antenna access points (APs) serving a much smaller number of users. There is no partitioning into cells and each user is served by all APs. In this paper, the uplink performance of cell-free systems with minimum mean squared error (MMSE) and large scale fading decoding (LSFD) receivers is investigated. The main idea of LSFD receiver...
In this paper, we extend the answer for the question: Do the gains from massive MIMO and coded caching cumulate? in a simple setting of downlink MIMO channel with Rayleigh quasi-static fading. Under some practical assumptions, the scalability of massive MIMO and coded caching alone with the number of users does not hold. On the other hand, we show that in this setting, the combination of both provides...
In this paper, a channel estimation scheme is presented for orthogonal frequency domain multiplexing based aeronautical multi-path channels with large time delays. An iterative algorithm is employed to jointly eliminate inter-carrier interference (ICI) and inter-symbol interference (ISI). Specifically, ICI is cancelled using a parallel iterative channel estimation method, which, based on first order...
Pilot contamination caused by non-orthogonal pilot sequences reuse in adjacent cells has become one of the main impairments for massive multiple-input multiple-output (MIMO) systems. A scheme named flexible pilot reuse is proposed in this paper to reduce the effect. The main idea is that users suffered from mild pilot contamination (PC) are allocated the same set of orthogonal pilots, while the users...
This paper presents optimum transmission strategies in terms of the number of transmission antennas and pilot symbols for secondary users of multiple-input and multiple-output system. By complying with the restriction of transmission power from geo-location database, secondary users can protect primary users. However, the receiver of secondary users can suffer from the interference by primary users...
In this paper, we identified the challenges and requirements for the waveform design of the fifth generation mobile communication networks (5G) and compared Orthogonal frequency-division multiplexing (OFDM) based waveforms with Filter Bank Multicarrier (FBMC) based ones. Recently it has been shown that Quadrature-Amplitude Modulation (QAM) transmission and reception can be enabled in FBMC by using...
In this paper, we propose an in-band full duplex (IBFD) cellular operation with reconfigurable uplink (UL) antennas at base station (BS). For handling mobile station (MS)-to-MS interference in an IBFD cellular system, a repetition coding of UL MSs is considered. While the repetition coding of UL MSs is applied, downlink (DL) MSs can cancel MS-to-MS interference by using one silent symbol to measure...
Interference is known to cause the performance degradation of the wireless network. To solve the interference problem, cooperative transmission scheme such as interference alignment (IA) is required. Channel state information (CSI) among IA participation nodes should be essentially obtained to implement IA. By implementing the IA prototype with obtaining the real environment CSI, we can check the...
In this paper, we consider two base stations (BSs) which maximize the achievable rate for two users connecting to each BS and sharing channel state information (CSI) in a multi-cell processing (MCP) framework. We propose a two way channel estimation or prediction process. Such framework has promising outcomes in terms of feedback reduction and achievable rates moving the system from one with unknown...
In this paper, a multi-pair amplify-and-forward (AF) massive MIMO system is investigated, where multiple source users communicate with multiple destination users via a single relay. The achievable rate of the system and its analytical expression are studied for power-scaling laws when ZFT/ZFR algorithm is adopted at the relay. The imperfect channel state information (CSI) is considered and the MMSE...
In massive multi-input multi-output systems, the pilot contamination has a strong impact on the performance. In this paper, an advanced channel estimation scheme by utilizing the angles of arrival (AoAs) of cell-edge users is proposed to alleviate the impact of pilot contamination. We exploit angle diversity and low-rank characteristic of the second-order statistical channel information to group cell-edge...
Sensor localization is one of the big problems when building large scale indoor sensor networks because GPS (Global Positioning System) is unavailable in indoor environments. We are developing a sensor localization system using WiFi APs as anchors, which requires no anchor deployment. Because sensor nodes cannot demodulate WiFi signals, we have developed a cross-technology RSS (received signal strength)...
This paper discusses about the performance of Staggered Multitone Filter Bank Multicarrier (SMT-FBMC) in multipath channel. Since SMT system suffers from intrinsic interference, therefore the use of pilot pattern that can be used in Orthogonal Frequency Division Multiplexing (OFDM) system will give a bad performance. We proposed some pilot patterns that can suppress intrinsic interference by setting...
In amplify-and forward (AF) cooperative systems, accurate channel state information (CSI) for both the cascaded and individual links is essential for coherent combining to achieve spatial diversity. The combined superimposed training strategy(TM+ST) is proposed, where the time-multiplexed (TM) training scheme is employed at source node (SN) to estimate the cascaded channel(S-R-D) while relay-assisted...
This paper presents a computationally efficient beamforming approach to combat wiretapping in a relay-based multiple-input multiple output (MIMO) communication system which is part of a cognitive radio (CR) network. The system operates in two stages, that is, multiple-access (MA) followed by broadcasting (BC) using physical layer network coding (PNC). The beamforming design is based on minimizing...
In this paper, we consider bandwidth efficient design and channel estimation over time-varying frequency-selective environments, where the basis expansion model (BEM) is used to describe the time-varying channel. Superimposed training based channel estimation based affine precoding model is designed, where the data interference is eliminated from received data prior to performing channel estimation,...
In HF communications, both intra-and inter-symbol fading and losses can vary significantly between two nodes. While these channel effects may be problematic for maintaining a link, they may provide information about the structure of the ionosphere. We utilize our previously developed communications simulator which simulates a received RF data stream for a given channel response. Using channel responses...
Filter bank multi-carrier with offset QAM(FBMC/OQAM) is a multi-carrier modulation technique that can be an alternative to conventional orthogonal frequency division multiplexing(OFDM) with cyclic prefix (CP) in wireless network. FBMC has a higher spectrum efficiency and effective emission power without CP. Because the orthogonality only exists in real domain, the channel estimation in FBMC/OQAM system...
The sum rate maximization problem in Interference Alignment (IA) is hard to be solved, for the sum rate function is non-convex. The Weighted Minimum Mean Square Error (WMMSE) algorithm settles this problem by converting the original problem into an equivalent convex one. In this paper, an enhanced version of the WMMSE algorithm is presented, which takes the statistical information of the channel estimation...
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