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In traditional cellular networks, cell edge users suffer from severe interference. This paper considers a cell free network scenario that multiple base stations (BSs) serve a group of users without cell boundary. Each user can only be served by its own BS according to the traditional cellular network paradigm, while in the user centric cell free network, users can be associated with multiple nearby...
Massive MIMO systems, where base stations are equipped with hundreds of antennas, are an attractive way to handle the rapid growth of data traffic. As the number of users increases, the initial access and handover in contemporary networks will be flooded by user collisions. In this work, we propose a random access procedure that resolves collisions and also performs timing, channel, and power estimation...
This paper jointly optimizes the precoding matrices and the set of active remote radio heads (RRHs) to minimize the network power consumption for a cloud radio access network (C-RAN) where both the RRHs and users all have multiple antennas. Both users' rate requirements and per-RRH power constraints are considered. Due to these conflicting constraints, this optimization problem may be infeasible....
This paper investigates multi-user multi-input multi- output cognitive wireless powered communication networks (WPCN), in which a secondary WPCN shares spectrum with a primary wireless information transfer system. A typical WPCN consists of two different phases. In the first downlink phase, a hybrid access point (H-AP) transfers energy to charge users, and then in the subsequent uplink phase, the...
In this paper, the security of multi-input single- output (MISO) amplify-and-forward relaying network with untrustworthy relay nodes is considered, where the untrustworthy nodes can help to forward the received signal and they may also try to decode such information, which can be regarded as potential eavesdroppers (Eves). To deal with such kind of smarter Eves, relay selection is adopted and both...
Wireless sensor networks (WSNs) consist of nodes with limited power resources. A potential method to prolong the lifespan of a node is the use of an antenna which can harvest energy from radio frequency (RF) signals. In this paper, we model a network consisting of nodes with energy harvesting capabilities and a number of dedicated energy transmitters (ETs) which send data to the nodes. We identify...
This paper investigates the performance of bidirectional dynamic networks (BDN) with massive multiple input multiple output (MIMO) systems. In BDN, dynamic allocation of the number of uplink and downlink remote radio heads (RRHs) is proposed, which offers a flexible solution to balance the data traffic asymmetry without requiring the time synchronization. Intuitively, the interference between the...
In this paper, we consider a T \times R massive MIMO system with up to R simultaneous links (T>> R>>1) and nonlinear amplifiers in each transmitter branch. The impact of a nonlinear amplification is analytically studied and accurate expressions for the spectral characterization of the transmitted signals, as well as the bit-error-rate (BER) are derived. The accuracy...
The idea of combining spatial modulation (SM) with massive multiple-input multiple-output (MIMO) system, i.e. massive SM-MIMO, has recently attracted plenty of academic interest, as it could simultaneously harness the advantages of SM and massive MIMO. However, the spectral efficiency (SE) analysis for massive SM-MIMO is still lack of exploring. To this end, a novel SE expression is derived in this...
The trustworthiness of nodes in a network is practically a complicated concept and strongly depends on the social relationship among the nodes. For a certain model of trustworthiness, the scheme can be optimized to achieve the highest average secrecy rate based on pre-defined information about possibly malicious nodes. In such a scheme, the secrecy rate is considered as a function of the maximum achievable...
In this paper, we present a new and significant theoretical discovery. If the absolute height difference between base station (BS) antenna and user equipment (UE) antenna is larger than zero, then the network capacity performance in terms of the area spectral efficiency (ASE) will continuously decrease as the BS density increases for ultra-dense (UD) small cell networks (SCNs). This performance behavior...
Software Defined Networking has been adopted to improve data center network efficiency. In SDN, the controllers are responsible for exchanging information with the switches to perform specific operations such as data forwarding. The transmission of control traffic usually uses networks different from data networks. However, building an additional wired network for the control traffic leads to high...
In this paper, we propose the concept of "channel+ beam" hando2642 (CBH) in cognitive radio networks (CRNs) with multi-beam smart antennas (MBSAs). We address the multi-class spectrum hando2642 issue, based on the user priority, by using the mixed Preemptive/Non-Preemptive M/G/1 queueing model with discretion rule. The discretion rule sets the threshold for the preemption of the low-priority...
This paper focuses on linear precoding designs in multi-user multiple-input multiple-output block diagonalization (BD) relay systems with limited feedback. A base station employs spatial multiplexing transmission based on quantized channel state information (CSI) obtained from a relay. Then the relay transmits the received signal to users equipped with multiple antennas. In this paper, we propose...
Millimeter-wave (mm-Wave) systems with $\mbox{hybrid digital-to-analog beamforming (D-A BF)}$ have the potential to fulfill 5G traffic demands. The capacity of mm-Wave systems is severely limited as each radio frequency (RF) transceiver chain in current base station (BS) architectures support only a particular user. In order to overcome this problem when high density of users are present, a new algorithm...
In this paper, we focus on the energy efficient joint resource scheduling scheme in time varying Cloud-RAN with delay sensitive traffic. We jointly consider the computation resources provided by baseband units (BBUs), which are modeled as the data processing rate of each virtual machine (VM) provided by the BBUs, and the antenna resources provided by the remote radio heads (RRHs), which are modeled...
In this paper, we study a wireless-powered communication network (WPCN) scenario, in which a multiple antenna amplify-and-forward (AF) two-way relay coordinates power transfer and information exchange to multiple pairs of users. A harvest-then- transmit protocol is assumed where the relay first transmits energy signals to the users in a power transfer phase. Multi-pair of users, which have rechargeable...
In this paper, we have proposed an iterative space alternating generalized expectation maximization (SAGE) based semi-blind channel estimation technique for massive multiple-input multiple-output (MIMO) system in multi-cell pilot contamination prone scenario. The benefits of massive MIMO depend largely on the accuracy of channel state information (CSI) available at the base station (Transmitter)....
Multiple antenna techniques, that allow energy beamforming, have been looked upon as a possible candidate for increasing the efficiency of the transfer process between the energy transmitter (ET) and the energy receiver (ER) in wireless energy transfer. This paper introduces a novel scheme that facilitates energy beamforming by utilizing Received Signal Strength Indicator (RSSI) values to estimate...
In this paper, we investigate the user pairing scheme in virtual multiple-input multiple-output (V- MIMO) systems, which can significantly improve system performance and spectral efficiency (SE) using multiuser diversity. Considering the development of green communication, we want to find the upper bound of energy efficiency (EE) under the constraint of SE. Firstly, the optimal transmit power allocation...
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