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Internet of underground things (IOUT) is an emerging paradigm which consists of sensors and communication devices, partly or completely buried underground for real-time soil sensing and monitoring. In this paper, the performance of different modulation schemes in IOUT communications is studied through simulations and experiments. The spatial modularity of direct, lateral, and reflected components...
Vehicular communication networks expect to accommodate the ever-increasing on-road wireless traffic by deploying roadside units (RSUs) and meanwhile exploiting existing wireless infrastructures. To achieve flexible deployment, energy-saving operation and low-latency services, a new type of RSUs, namely cache-enabled green RSUs are introduced, which can store popular contents locally and harvest renewable...
In this paper, we consider the problem of admission control of wireless virtual network (VN) service requests in a multi-service network with service-specific service function chains (SFC). SFC imposes traversal constraints on flows, i.e., each flow must visit certain service-specific nodes in a specific order. We leverage the fact that all flows within a service have common traversal constraints...
Massive Multiple-Input Multiple-Output (MIMO), small cell, and full-duplex are promising techniques for future 5G communication systems, where interference has become the most challenging issue to be coped with. In this paper, we provide an interference coordination framework for a two-tier heterogeneous network (HetNet) that consists of a massive-MIMO enabled macro-cell base station (MBS) and a number...
Conventional microwave bands are expected to encounter bandwidth shortage due to the ever-increasing demand for high speed wireless services. The use of millimeter wave (MMW) spectrum has been regarded as one of the promising solutions to support data traffic demands in future cellular networks. MMW cellular networks are envisioned to be densely deployed to attain acceptable coverage and rate. In...
Relay selection is a simple yet effective means to improve the reliability and coverage of wireless cooperative networks. However, it suffers from inefficient use of the available bandwidth resources. This paper introduces the use of content caching at relays in order to tackle this problem and improve the performance of relay selection. Three cache placement schemes are considered: one based on the...
In this paper, optimal content caching strategy is proposed to jointly minimize the cell average outage probability and fronthaul usage in cloud radio access network (Cloud-RAN). Closed form expression of the outage probability conditioned on the user's location is presented, and the cell average outage probability is obtained through the composite Simpson's integration. The caching strategy for jointly...
It is well-known that wireless channel reciprocity together with fading can be exploited to generate a common secret key between two legitimate communication partners. This can be achieved by exchanging known deterministic pilot signals between both partners from which the random fading gains can be estimated and processed. However, the entropy and thus quality of the generated key depends on the...
While buffer-aided relaying improves the diversity of a multi-hop network, its deployment introduces time-delays, thus rendering buffering unreliable for delay-intolerant applications. To alleviate excessive delays, various studies propose delayaware protocols, but at the expense of reduced diversity, and consequently, increased outage probability. Attempts to maintain the diversity of the system...
Full duplex (FD) communications, which increases spectral efficiency through simultaneous transmission and reception on the same frequency band, is a promising technology to meet the demand of next generation wireless networks. In this paper, we consider the application of such FD communication to self-backhauled small cells. We consider a FD capable small cell base station (BS) being wirelessly backhauled...
This work studies the secrecy outage performance of buffer-aided dual-hop multi-antenna relay systems without eavesdropper's channel state information (CSI). By modeling the dynamic buffer state transitions with the Markov chain, the secrecy outage probability at each state is investigated and the stationary distribution probabilities of all states are subsequently derived. Using the total probability...
This paper studies the power minimization problem for non-orthogonal multiple access (NOMA) downlink systems, in which nodes are equipped with multiple antennas. We develop a joint power allocation and receive beamforming algorithm using the fixed-point update power allocation method under two types of channel state information (CSI). Particularly, we first assume that perfect CSI is available for...
This paper concerns multiple time delays in power and rate control for wireless communication networks with external disturbance. Based on the mathematical state-space model established for the wireless communication networks with state delay and input delay, a compensation algorithm for multiple time delays of general form model is researched and it can be applied into our model. An optimal tracking...
This paper studies multi-group multicast beamforming with a hybrid large-scale antenna array in millimeter wave (mmWave) communication systems. A low-complexity hybrid structure is adopted, where each RF chain is only connected to part of the antenna elements. We formulate a hybrid analog and digital beamforming design problem for multi-group multicast transmission with the objective of minimizing...
Distributing scarce spectral resources among the unlicensed users has been an attractive research area for Cognitive Radio Network's (CRN) research community. A resource distribution technique, which emphasizes fairness, ensures allocation of resources for all Secondary Users (SUs) irrespective of their data rates and may cause efficiency loss for the CRN. On the other hand, a throughput based resource...
In this paper, a new spectrum sensing (SS) method, called maximum-to-mean energy detector (MMED), is proposed. Considering a wireless communication system with many angles of arrival (AoA), the suggested method is based on beamforming and the ratio of the maximum energy to the mean one of the received signal. The proposal is totally blind and it does not require the knowledge of the signal, the channel...
This paper investigates the performance of cooperative non-orthogonal multiple access (NOMA) systems, where one near user works as a decode-and-forward (DF) full-duplex (FD) or half-duplex (HD) relaying to help far user. Two cooperative relay scenarios are considered insightfully. 1) The first scenario is that no direct link exists between the base station (BS) and the far user; and 2) The second...
We consider a multiple access relay channel (MARC) network consisting of two sources, one relay, and one common destination applying compute-and-forward (CF) strategy. We show that the direct application of CF to the MARC network results in poor error performance bounded by (p + 1)−1, the probability of rank deficiency of the coefficient matrix over Fp. To solve this problem, we propose two practical...
This paper presents a modified MMSE channel estimation for turbo equalization in uplink massive multiple-input multiple-output (MIMO) systems with pilot contamination. Unlike other work on channel estimation in massive MIMO systems where perfect knowledge of inter-cell large scale channel coefficients is assumed, a modified method for data-aided MMSE estimation is proposed without requiring the knowledge...
Since more than a decade, wireless sensor networks is a very attractive field in computer science and networking. Battery management is a crucial issue in the area of wireless sensor networks. The communication between a source node and a destination one may fail if both nodes are located inside a deep shadow-fading zone. Relay-selection strategy has been used in order to extend amplify-and-forward...
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