Yinghai Zhang

Component carrier selection for LTE-A systems in diverse coverage carrier aggregation scenario

Each UE can aggregate multiple component carriers (CCs) as a wider band to support the demand of higher data rates in LTE-Advanced (LTE-A) systems with carrier aggregation (CA). An appropriate CC selection is necessary in order to improve the utility of CA, since not all CCs benefit from CA due to bad channel quality of some CCs. Most of existing methods only take one aspect of problems into account like channel quality or traffic load separately. To improve the system capacity under a good load balance condition, a Utility-Balance based CC Selection (UB-CS) strategy is proposed for the non-continuous diverse coverage deployment scenario in LTE-A CA system. Simulation results demonstrate that the given scheme is prior to the traditional ones.

Unidirectional link-state advertisement based on power control for MANET

Abstract Link states are studied in ad hoc network. The characters of unidirectional links are discussed. Unidirectional link-state advertisement based on power control mechanism (ULAPC) for mobile ad hoc networks (MANET) is designed. ULAPC is able to advertise unidirectional link-state to relational nodes. And it may offer help for process of routing discovery in ad hoc network. Based on ULAPC, the routing method solving the problem of unidirectional link is described in ad hoc network. Simulation results show the performance of ULAPC is better than the traditional routing protocols in many aspects.

Code division cooperative identification reader anti-collision protocol in smart RFID systems

In this paper, an anti-collision protocol called code division cooperative identification protocol (CDCIP) is proposed in order to tackle the reader collision problem in smart RFID systems. CDCIP allocates orthogonal sequences to each reader and composes a RFID network. Consequently, it strives to let more than one reader work at the same time and at the same frequency. Eventually, comparing with the traditional protocol, the simulation results show that the proposed protocol offers better average throughput and lower power consumption of the system.

Spectrum-driven sleep scheduling algorithm based on reliable theory in cognitive radio sensor networks

Abstract Sleep scheduling mechanism is used in the tradition sensor network to conserve battery power. However, in cognitive radio sensor networks (CRSNs), the sleep scheduling mechanism needs to consider the constantly changing spectrum states and makes some adjustments. In this paper, a heterogeneous hierarchical CRSNs model is briefly described and the reliable theory is introduced to construct the centralized sleep scheduling mathematical model. Whats more, considering the both traffic and sleep periods of sensor nodes, the spectrum-driven sleep scheduling algorithm (SSSA) for CRSNs is proposed and analyzed. The simulation results show that the traffic holding rate and energy efficiency can gain significant improvements.

Distributed two-hop proportional fair resource allocation in Long Term Evolution Advanced networks

In Long Term Evolution Advanced networks with Type I in-band half-duplex decode-and-forward relay nodes, proportional fair PF resource allocation is aiming at guaranteeing two-hop match and optimising global proportional fairness. The two-hop match is defined as equal data rates in the access links and the corresponding backhaul links. The global proportional fairness is between all the user equipments served by the evolved nodes B and the relay nodes. Existing centralised schemes achieve these targets at the cost of enormous channel state information CSI exchange. Existing distributed schemes focus on resource partitioning and employ a traditional single-hop PF scheduling algorithm in access links, with less CSI exchange. The traditional PF scheduling algorithm maximises single-hop proportional fairness between the data rates in the access links rather than two-hop proportional fairness between the end-to-end data rates in the two hops. In order to reduce CSI exchange and at the same time to maximise the two-hop proportional fairness, a distributed two-hop PF resource allocation scheme is proposed. The proposed scheme includes two-hop PF resource scheduling algorithms and adaptive resource partitioning algorithms, applied in different two-hop transmission protocols. Simulation results demonstrate the proposed scheme is better than the existing distributed schemes in obtaining better proportional fairness and larger cell-edge user equipment throughputs. Copyright

Adaptive time-slot and power allocation in MIMO systems for simultaneous wireless two-way information and one-way energy transfer

RF energy harvesting based on wireless energy transfer (WET) can release mobile terminals from battery constraint and has drawn significant research interest. In this paper, in order to solve the problem of Simultaneous Wireless Two-Way Information and One-Way Energy Transfer (TWI & OWE-SWT) in MIMO systems, an Adaptive Time-slot and Power Allocation Scheme (A-TPAS) is proposed. And to maximize the effectiveness of channel utilization, we define the Effective Throughput (ET) as a metric to evaluate the system performance rather than the traditional sum throughput. Subsequently, the A-TPAS is optimized through Improved Stochastic Ranking Evolution Strategy (ISRES) and the optimal allocation is obtained. Finally, the numerical simulation results verify that our scheme can suppress inter-cell interferences and maximize the sum of ET and it performs better than existing one.

A novel cooperative spectrum sensing scheme based on virtual soft information fusion

Abstract In cognitive radio (CR), the performance of hard information fusion (HIF) strategy for cooperative sensing will deteriorate when cooperative CR user are not uniformly reliable. To deal with this problem, this paper proposed a novel virtual soft information fusion (VSIF) strategy which uses expectation for primary users (PU) presence probability to replace the local sensing decision of each user in the information fusion. Compared with the HIF-based scheme, VSIF-based sensing scheme keeps the advantages of low data transmission in HIF-based scheme, and modifies the way of information fusion at the fusion center to achieve better performance when the user sensing reliability is non-uniform. Simulation shows VSIF strategy has significant superiority on the missing detection probability over HIF in the scenarios of non-uniform user reliability.

Research on the novel asymmetric frequency division duplex technique

This article introduces a novel duplex transmission technique-asymmetric frequency division duplex (AFDD). One of the characteristics in future mobile systems is asymmetric characteristic caused by service requirement and electromagnetic radiation, AFDD is designed to adapt to the new asymmetric characteristics. The AFDD puts forward a novel adaptive frequency-allocation scheme in downlink and uplink. Combining AFDD with code division multiple access (CDMA) communication system, it is proven that AFDD improves the capacity and coverage of the system compare with FDD CDMA system.

A Distributed Interference Alignment Approach Based on Grouping in Heterogeneous Network

To effectively mitigate interference and improve the performance, we propose a grouping-based two-stage distributed interference alignment (GTDIA) scheme for a two-layered heterogeneous network (HetNet) in multi-user multiple-input-multiple-output (MIMO) Gaussian downlink transmission scenario. In this paper, we first extend the grouping-based interference alignment (GIA) scheme, which is suitable in single-layer multi-cell scenario to a two-layered HetNet. Then, in order to improve the system performance and reduce the computational complexity, we propose a new interference alignment (IA) scheme (i.e., GTDIA) by grouping pico users (PUEs) to align inter-layer interference (inter-layer IF) and design the receive beamforming matrices of PUEs. Since the macro users (MUEs) are located randomly under the coverage of macro base station, the inter-layer IF is between some pico base stations and MUEs. Specifically, two-stage (i.e., a composite of two cascade matrices) transmit beamforming matrices of base stations are designed to cancel both of the inter-layer and intra-layer interference among MUEs. Furthermore, because of the reciprocity of time-division duplex system, a distributed algorithm is used when designing the second stage transmit beamforming matrices. Analysis and simulation results demonstrate that the proposed scheme outperforms the extended GIA and other conventional IA schemes.

Interference Assessment for the Spectrum Sharing between IMT-2020 and Inter-Satellite Service

This paper analyzes interference coexistence of IMT-2020 (International Mobile Telecommunications-2020) and intersatellite service where both systems operate in the same spectrum band of 25.25-27.5GHz. This work can be regarded as a good reference to the research community, industry and regulators which are currently investigating spectrum requirements and technology options for 5G system. Considering the interference scenario between the return inter-orbit link of data relay satellite system and downlink of IMT-2020, we adopt realistic system parameters and radiation pattern, combined with very recent channel from the literature. Simulation results indicate that the interference from IMT-2020 downlink to Data Relay Satellite (DRS) is above the interference level while the LEO spacecraft cause acceptable interference to IMT-2020 downlink..