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An improved minimum mean square error (MMSE) channel method with low complexity is proposed for the massive multiple input multiple output (MIMO) system. In the method, the covariance matrix in the MMSE method is firstly approximately estimated by the received signal, where the optimal approximated weight is given, and then the Sherman-Morrison theorem is employed to transform the matrix inversion...
We investigate device-to-device (D2D) communication underlaying cellular networks with M-antenna base stations. We consider both beamforming (BF) and interference cancellation (IC) strategies under quantized channel state information (CSI), as well as, perfect CSI. We derive tight closed-form approximations of the ergodic achievable rate which hold for arbitrary transmit power, location of users and...
Due to the severe interference from the cellular users who share the same spectrum resources in cellular networks, the reliability of D2D communication has been a great concern. Relay has always been considered a importantl tool in improving the quality of wireless system. This paper combines D2D communication system with relay to make D2D communication more reliable. We can conclude from the simulation...
This paper studies the outage probability of device-to-device (D2D) communication aided by another D2D user using the two-way amplify-and-forward (AF) relaying protocol. We first discuss the outage behavior under strong and weak interference from the cellular network. Then the exact expressions for the outage probability under the two cases are derived. Based on these results, we give tight approximations...
Recently, FCF (Fountain-Coding-and-Forward) relay has been proposed as an effective method to improve the performance of the wireless system. In addition, device-to-device(D2D) communication can effectively improve the system's resource usage efficiency and reduce the user's energy consumption. In this paper, we study the performance of a hybrid cellular network with the FCF relay strategy considering...
Applying MIMO technology into handheld equipments has always been a widely argued problem due to their body and power limit. The appearance of device-to-device (D2D) communication provides one way for solving this problem. In this paper, we developed the way to construct virtual antenna array by D2D links and find the method to get diversity gains using space time block coding between inter cluster...
This paper considers a new strategy utilizing two-way decode-and-forward (DF) relaying for device-to-device (D2D) communications underlaying cellular networks. Assuming that all the terminals have single antenna, we first derive the sum-rate expressions for both the D2D and cellular links and then propose a Pareto-optimal method to maximize the achievable sum-rate of both D2D and cellular links. Simulation...
In this paper, we investigate the outage probability of device-to-device (D2D) communication assisted by decode-and-forward (DF) relay node and that using traditional strategy. We assume all terminals are equipped with single-antenna. We first derive closed-form expressions for the outage probability of the D2D link under asymmetrical and symmetrical cases respectively. Then we derive tight approximations...
Device-to-Device (D2D) communication underlaying cellular network is a promising technique of local service to improve the system capacity and spectral efficiency. While, large amount of interference can be caused by sharing the resources between the cellular users and D2D pairs, so an optimal resource allocation method is necessary to coordinate the interference. In generally, the OFDMA can not be...
Device-to-Device (D2D) communication underlaying cellular networks can improve resource utilization and thus increase total throughput. However, resource allocation and interference coordination between cellular networks and D2D system will become critical and need to be properly handled. According to some papers, which just allowed a set of cellular user equipment (UE) and a pair of D2D UEs to coexist...
The selection of relaying node has an important influence on the D2D system performance. Previous literatures always utilize one selection strategy and consider only the reliability of the system. The strategy we propose determines which relay scheme to use according to the specific communication context. After the best relaying node is determined, we do the power allocation for that best relay for...
Future cellular networks such as IMT-Advanced are expected to allow Device-to-Device (D2D) communication as an underlay. During the downlink period, both of the D2D receiver and cellular user will suffer from interference caused by radio resource sharing. In this paper, a joint resource allocation and resource reuse scheme is investigated, in which resource allocation to cellular users is employed...
In this paper, we propose a novel hybrid random access policy based on spectrum occupation. In this algorithm, cognitive users are provided with three times to access the network by Underlay mode or Interweave mode according to access probability p. As a result, spectrum resources can be fully utilized and decent communication quality is also ensured. Furthermore, a power control model based on outage...
Abstract-Load control is an important component of wireless resource management (RRM).It detect system load in period and provide a suitable solution to make sure that system load below threshold.Load control algorithms can be devised from a multi-cell perspective.This allows the reduction of the load in a given reference cell.In particular,this can be beneficial when service distribution is not homogeneous...
TD-SCDMA truncking system is a developing direction in digital truncking system. Based on TD-SCDMA trunking system, a movable boundary dynamic channel allocation (MB DCA) scheme is proposed. The characteristic of the algorithm is that the data service can borrow the voice channel for data transmission when the voice channel is idle and the data register queue is not empty. When a new voice call comes...
This paper studies the uplink load control strategies of TD-SCDMA system combined with the characteristics and standards of trunking service. Through the simulation, we propose an appropriate uplink load control strategy for TD-SCDMA trunking system, which is based on existing protocol standards. The congestion detection is at base station, while the congestion solution is at RNC. Through a period...
In this paper the problem of power control in cognitive radio system is approached from the perspective of non-cooperative game theory, and an algorithm is presented. A new utility function for mobile terminals is defined, and a detailed analysis of the existence and uniqueness of Nash equilibrium for the utility function. A effective sigmoid efficiency function and a new pricing mechanism called...
To exploit the effect of modulation schemes on the best relay selection, a novel Jointing Modulation schemes max-min criterion (JM-max-min) is proposed firstly for Two-Way De-Noise-and-Forward (DNF) Opportunistic Relaying systems (TW-DNF-OR) by aiming at minimizing the Pairwise Error Probability (PEP) of Multi-Access (MA) phase which dominates the error performance of TW-DNF-OR due to the presence...
Cognitive Radio is an effective solution to the current shortage of spectrum resources. One of the key technologies is open spectrum allocation. In this paper, an improved spectrum allocation algorithm based on proportional fairness is proposed. An adjusting factor of channel quantity is introduced based on traditional labeling system, which has effective inhibitory functions for nodes who occupy...
An important problem of cognitive radio (CR) is how to make use of spectrum resources effectively. Spectrum sharing is one of the key technologies for addressing problems. Based on the existing spectrum sharing scheme of non-cooperative game theory, an improved utility function of the secondary user is proposed by introducing a new reinforced factor which is based on spectrum occupancy of the secondary...
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