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Recently, 802.11ah with restricted access window for collision attenuation has been proposed for Internet of Things (IoT) applications. Random grouping of nodes in different access window is utilized to reduce the hidden node collision probability. However, when the coverage area of the sink node is large, the occurrence probability of hidden node problem is still high and severely impacts the system...
This paper researches on millimeter-wave (mm-wave) channel estimation based on interference cancellation (IC) and DOA (Direction of Angles) estimation in hybrid massive MIMO systems. According to the ray-tracing model, the mm-wave channel estimation problem can be solved by converting into the estimation of parameters including the angles of departure (AOD), the angles of arrival (AOA) and the path...
Video streaming over networks has grown rapidly in recent years. Increasing focus has gradually turned from Quality of Service (QoS) awareness to user Quality of Experience (QoE) awareness. In this paper, we propose a unified QoE prediction framework for HEVC encoded video streaming. Firstly, the impact of network impairment on QoE is modelled by packet loss rate. Secondly, features of HEVC encoding...
In this paper, by first analyzing the circuit model of series-parallel compensated inductive power transfer (IPT) system, the relation among voltage gain, transfer efficiency, operation frequency and load resistance is obtained. According to the analysis, a novel design of series-parallel compensated IPT system realizing optimized transfer efficiency and voltage gain regardless of load resistance...
Detection probability is one of the most important criteria in the satellite-based automatic identification system. It represents how many vessels can be detected in the monitoring area of the system. However, existing research often neglects practical factors in S-AIS (satellite-based AIS) and cannot assess the performance of a practical system. In this paper, we propose a much detailed collision...
Single Carrier-Frequency Division Multiple Access (SC-FDM) and Tone Reservation (TR) are used independently to reduce Peak to Average Power Ratio (PAPR) in wireless communications. In this paper, we jointly consider TR and SC-FDM to achieve much lower PAPR. We first present the PAPR of SC-FDM system with different DFT/IDFT size, and then theoretically analyze the PAPR gain of TR in SC-FDM. By considering...
Space-based Automatic Identification System (AIS) uses Gaussian minimum shift keying modulation (GMSK) as the modulation scheme. Thus, Viterbi Algorithm (VA) is commonly implemented considering the tradeoff between performance and complexity. For the further improvement of the performance of Viterbi decoding, we propose a Soft-Output Viterbi Algorithm for AIS receiver (SOVA-AIS) in this paper. The...
Video streaming over networks has grown rapidly in recent years. Increasing focus has gradually turned from Quality of Service (QoS) awareness to user Quality of Experience (QoE) awareness. In this paper, we propose a subjective QoE model based HEVC encoder adaptation scheme for multi-user video streaming. Firstly, the impact of HEVC encoder on video streams is investigated with different configurations...
Because of the wide field of view (FOV) to monitor vessel movements, satellite-based automatic identification system (S-AIS) has been promoted in recent years. However, synchronization is a tough work in S-AIS receiver because of the large Doppler shift and serious signal collision resulting from simultaneous transmission in the FOV of a satellite. In this paper, we propose a pipelined synchronization...
Random access algorithm is critical for the performance of interactive broadcasting system. Random access with Dynamic Window Size and Random Access Slots(D-WS-RAS) is proposed as an efficient way to tackle this problem in the interactive broadcasting system. This algorithm is composed of three parts: utilize Bayes' rule to estimate the number of access, dynamically set backoff window size and dynamically...
The rapid growth of video in wireless networks is a crucial issue to be addressed by content providers. Nowadays, an emerging and promising trend is the development of solutions aimed at maximizing the quality of experience (QoE) of end users. However, the prediction of the QoE perceived by users in different conditions remains a major challenge. In this paper, we propose a two-layer hierarchical...
In this paper, we propose a novel distortion calibration algorithm for uniform circular array (UCA) based on its special structure. A near-field calibration antenna, located in the center of circular array, is used to estimate the gain and phase uncertainties of elements. Besides, a single far-field source is used to estimate the direction-of-arrival (DoA) and mutual coupling matrix (MCM). Finally,...
A fundamental problem in wireless networks is to develop an effective communication protocols that achieve high throughput by using user's diversity. In broadcast system. Thus, users with better channel performance has to wait others to receive all information, and results in a waste of the wireless resources. To cope with this problem, we propose a novel fountain code called Unequal Fountain code...
To satisfy interaction between users and service providers (SP) in lots of rural areas without enough communication infrastructure, a dedicated return channel for the terrestrial digital TV is demanded. Therefore, we propose a specification on Dedicated Return Channel (DRC) based on SC-OFDMA technique for future broadcast, and promote it to Advanced Television Systems Committee (ATSC). To efficiently...
Broadband communication is demanded to satisfy a much wider variety of multimedia services. Among the multi-carrier schemes proposed in recent years, Orthogonal Frequency Division Multiplexing Access (OFDMA) and Single-carrier Frequency Division Multiple Access (SC-FDMA) are the most appealing candidates for broadband systems. However, traditional sampling scheme with a single high-rate Analog Digital...
Due to the harsh Quality of Service (QoS) requirements of video streaming, it is a great challenge to provide multimedia service over wireless networks. In this paper, we consider video transmission in IEEE 802.11e networks, and propose a Load Adaptive Dynamic Mapping (LADM) scheme to improve the video transmission quality. In LADM, the enqueue rate of different kinds of packets and the dequeue rate...
In this paper, we propose an Iterative Collision Recovery (ICR) method to significantly alleviate the hidden terminal problem in OFDM based Wireless Local Area Networks (WLAN). We prove that when hidden terminal exists, more than half of the overall collisions are repeated because of the retransmission and binary exponential backoff mechanisms in IEEE 802.11. ICR is designed to recover the repeatedly...
Time synchronization is important for many distributed applications in Underwater Acoustic Networks (UANs) with large propagation delay, such as precise scheduling, target tracking and energy conservation. In this paper, we prove that the accuracy of time skew estimation increases as the number of overheard packet exchange from other neighboring nodes increases, and propose a light-weighted synchronization...
In this paper, we propose a Differential Overlap Decoding(DOD) algorithm to solve the hidden-terminal problems in OFDM based WLAN systems. DOD exploits the retransmission and random-jitter features of WLAN to decode the collided packets as a whole. DOD provides with new methods and views to jointly separate and decode collided packets in OFDM based system. In DOD, we formulate IFFT/FFT, channel influence...
Bit-Interleaved Coded Modulation (BICM) with rotated constellation is utilized to increase the signal space diversity in the second generation digital video broadcasting system, i.e., DVB-T2. However, at the receiver side, the complexity increases with product of the number of constellation points and the modulation order. In this paper, we propose a low-complexity iterative demapping algorithm which...
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