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The massive MIMO (multiple-input multiple-output) technology plays a key role in the next-generation (5G) wireless communication systems, which are equipped with a large number of antennas at the base station (BS) of a network to improve cell capacity for network communication systems. However, activating a large number of BS antennas needs a large number of radio-frequency (RF) chains that introduce...
With the development of wireless devices and the increase of mobile users, the operator’s focus has shifted from the construction of the communication network to the operation and maintenance of the network. Operators are eager to know the behavior of mobile networks and the real-time experience of users, which requires the using of historical data to accurately predict future network conditions....
One of the main trends in the fifth generation (5G) cellular network is the bifurcation of systems that enable network densification. With this trend, ultra-dense networks (UDN) become a pillar technology to provide high data rates gains. However, these gains come at the expense of more complex interference and higher handover frequency. The user-centric virtual cell conception has been proposed to...
Self-healing is one of the most important parts in self-organizing mobile communication network. It focuses on detecting the decline of service quality and finding out the cause of network anomalies and repairing it with high automation. Diagnosis is a particularly important task which identifies the fault cause of problematic cells or regions. To perform the diagnosis, this paper presents two modified...
In this paper, we consider joint optimization of Component Carrier (CC) selection and resource allocation in 5G Carrier Aggregation (CA) system. Firstly, the upper-bound system throughput with determined number of CCs is derived and it is proved by using graph theory that the throughput optimization problem is NP hard. Then we propose a greedy based algorithm to solve this problem and prove that the...
Carrier aggregation (CA) is considered to be a potential technology in next generation wireless communications. While boosting system throughput, CA has also put forward challenges to the resource allocation problems. In this paper, we firstly construct the energy efficiency optimization problem and prove that the function is strictly quasi concave. Then we propose a binary search-based power allocation...
The 5G wireless communication system supports varied applications, making the uplink/downlink traffic asymmetry more and more serious. Dynamic time division duplex (TDD) technique has become a key technology of 5G networks due to its flexibility to support asymmetric services. In this paper, we study dynamic TDD sub-frame reconfiguration algorithm based on shifting. Firstly, we define cell shifting...
Next generation (5G) mobile communication systems has a goal of ultra-high peak data rate. Ultra-Dense Network (UDN) is viewed as one of the key technologies to meet this challenge. The trend of network densification brings more complex interference. To solve this problem, a novel user-centric virtual cell design is proposed. Considering the changes of virtual cell load, we propose a load-aware virtual...
Zero-Forcing (ZF) algorithm is used to eliminate interference in small scale interference network. With the number of users increasing, the traditional ZF algorithm does not work effectively due to the fact that the channel matrix cannot provide sufficient dimensions to isolate interference. In this paper, we propose a Coordinated Zero-Forcing Beamforming with Clustering(CZFC) scheme to improve the...
In order to further improve the user experience in Hotspot or Indoor areas, Ultra-dense smallcell deployments in a new and high frequency band, e.g., 3.5 GHz, have been identified as a very interesting topic in Long Term Evolution—Hotspot or indoor (LTE-Hi) Release 12. The intra cluster interference among small cells becomes the main challenge instead of the cross layer interference for macro cell...
Considering environment protection and cost-efficiency, cloud radio access network (C-RAN) has received considerable attention. In C-RAN, centralized baseband units (BBUs) are composed of high-capacity processing units and realtime virtualization, so the BBU can control resource allocation according to the distribution of users, which will keep the system work with the highest bandwidth efficiency...
In this article, an exact closed-form expression is derived for outage probability of decode-and-forward (DF) cooperative communications over independent identically distributed Nakagami-m fading channels. Simulation results verify that the theoretical expressions for the outage probability are correct. The optimal power allocation based on the derived outage probability is also studied.
Considering a wireless relay network composed of a source, several relays and a destination where the source transmits data packets to the destination through both direct and relay paths, a multi-timeslots network coding (MTNC) scheme is proposed to combat the lossy nature of wireless channel where the relay nodes with satisfying relay-destination (r - d) channel state firstly perform network coding...
Hybrid forwarding scheme for wireless relaying is able to adapt to changing channel conditions by switching between amplify & forward and decode & forward, so as to decrease the energy consumption, time delay and complexity in practical system. The strategy evaluates the SNR at the relay and set it as the selection criteria. Although the BER performance for hybrid forwarding has been analyzed...
Cooperative communication usually shares a common model-one source, several relays and one destination. In this paper, we consider the multi-source scenario in a cell to carry on cooperative communication. However, multi-user setting might causes interference in the network, given this interference, the process of relaying selection applies SINR (signal to interference noise ratio) as a criterion...
In this article, the outage probability behavior of a relay network over Nakagami-m fading channels is analyzed. Both reactive and proactive opportunistic decode-and-forward (DAF) strategies are considered. The closed-form solutions to the outage probabilities on both opportunistic DAF strategies are derived. Simulation results confirm the presented mathematical analysis.
Current deployed emergency communications systems are only available to the rescuing workers. In this paper, a framework of wireless emergency communications is proposed for common communications in the disasters based on relaying and cognitive radio. In this framework, relaying provides small coverage expansion and high capacity for common communications. On the other hand, cognitive radio based...
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