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Using a large number of power amplifiers brings serious nonlinear distortion to 5G communication systems, which becomes a challenging problem for conventional digital predistortion (DPD) to linearize signals. To address this challenge, we propose a digitally assisted nonlinearity suppression architecture for applications in multiple antenna arrays. In this architecture, we use an auxiliary array to...
Content-centric Networking (CCN) is a new Internet architecture, relies on in-network caching to achieve an efficient and reliable content distribution. However, the existing forwarding strategy cannot fully sense the location of cache, because it is rely on the ports of routing table. In this paper, we propose a Bidirectional Cache Locating Algorithm based on Ant Colony Optimization (BCLA) using...
Mobile Ad hoc Network (MANET) is a collection of self-organizing wireless nodes without any fixed infrastructure and centralized administration. This article presents an investigation with an objective to compare the performance of two typical routing protocols, AODV and DSR, in real multi-hop environment. Apart from testing the end-to-end packet loss, delay and routing path parameters, we also assess...
Long Term Evolution (LTE) is commonly deemed to be a promising system for the future High-Speed Railway (HSR). The object of this paper is modeling of the broadband multipleinput multiple-output (MIMO) train-ground channel in LTE system based on the measurements on HSR viaducts. A couple of measurement campaigns are conducted along the Harbin-Dalian passenger dedicated line. The statistical distributions...
Content-centric networking represents a promising architectural direction to develop effective and efficient solutions for ad hoc networks, in which communications are driven by contents instead of host addresses. In this paper, we propose Best Route, Error Broadcast (BREB), a content-centric forwarding protocol for MANETs. BREB lays emphasis on the optimal use of available routes to address high...
Abstract-The opportunistic routing is popularly employed in the wireless multi-hop network. To obtain higher delivery rate and longer lifetime of network, we propose an adaptive energy-based updating opportunistic routing (AEUOR). We firstly introduce a novel priority metric of the routing selection in order to guarantee delivery rate. Then, an adaptive update algorithm is realized by efficiently...
The traditional personal computers have many security problems and are difficult to manage, thus desktop virtualization has been widely used due to its centralized management characteristic in solving the above issues [1]. In this paper we propose and discuss using Virtual SAN to enhance the performance of virtual desktop infrastructure. Using Virtual SAN can not only meet the requirement of virtual...
This paper focuses on the modeling of High-Speed Railway (HSR) multiple-input multiple-output (MIMO) systems. By using the geometry-based statistical method and ray tracing technique, a train-ground channel model based on the measurement of actual channel is proposed. Then the time-domain attenuation, channel capacity, Doppler power spectrum are simulated and analyzed to verify the validity of our...
The key factors for a routing protocol in Ad Hoc networks include route discovery, route maintenance and route destroy. Our laboratory has done a lot of researches based on our Ad Hoc hardware platform applying the classical AODV protocol. We found out that an essential cause for unsuccessful route discovery, instable route or even the limitation of hop numbers can be summarized as the bad channel...
Content-Centric Networking (CCN) focuses on content acquisition rather than end-to-end communication by decoupling content resources from special hosts. CCN does not need maintain stable paths between nodes and is independent of IP addresses, which make CCN convenient and efficient for mobile ad hoc network (MANET). In this paper, we develop an analytical model of content acquisition for Content-Centric...
Opportunistic routing (OR) is an effective way to guarantee transmission reliability in wireless multi-hop networks. However, little research focuses on transmission efficiency. Thus, an analytical model based on open queuing network with Markov chains was proposed to evaluate the efficiency. By analyzing two typical ORs, we find duplicate transmission and collision avoidance overhead are the root...
Resource allocation is one of the key issues in long term evolution (LTE) systems. In this paper, we propose an adaptive resource allocation scheme with quality of service (QoS) guarantees to maximize system throughput for high-speed mobile LTE systems. In this scheme, considering that channel quality indicator (CQI) might be changed in fast mobile scenarios which can reduce the system throughput,...
In order to solve channel estimation's pilot interference problem, this paper researched OFDM system channel estimation model, analyzed the OFDM symbol's pilot pattern, proposed a new octagon guide frequency pattern design method, and combined with low signal to noise space of virtual pilot technology, used the interpolation method to eliminate interference, further improved the OFDM system channel...
In this paper the innovative fixed-point LTE handover algorithm for the high-speed railway environment is proposed. The handover process effectiveness is researched through the measurement of information gathered by User Equipment (UE), such as the cell Reference Signal Received Power (RSRP) and the target cell Block Error Rate (BLER), which are analyzed for different points between the LTE eNodeB...
This paper presents an high-throughput routing metric, which concentrates on optimizing the behavior of expected transmission count metric (ETX) in real-world multi-hop Ad hoc networks. In practical applications, ETX metric always fluctuates over time even in fixed scenarios, and does not incorporate the effects of gray area and fluctuating links. Considering these drawbacks, we devise the average...
Handover (HO) is one of the key procedures, which ensures user equipment (UE) moving smoothly in long term evolution (LTE) systems. Generally, hard handover has a high outage probability and is relatively simple, but when the velocity of UE is high, the procedure may be unreliable, especially for VoIP service. In the special scenario high-speed railway, network deployment is known and an optimized...
In real-world Ad hoc networks, nodes have heterogeneity which is reflected in unidirectional and asymmetric links. Unidirectional links often lead to establishing route difficultly, long route path construction time, routing handoff frequently and randomly etc al. The performance of Ad hoc On-demand Distance Vector (AODV) routing protocol based on symmetrical and bidirectional routing path is severely...
The increasing interest that has been drawn to LTE system used in High-Speed Railway therefore requires measurement and analysis of broadband mobile channel for train-ground communications. By the approval of the Ministry of Railways of China, extensive and practical measurements are performed on Harbin- Dalian passenger dedicated line with the maximum running speed of 370 km/h. Based on the hierarchical...
Distributed cooperation among the forwarding candidates is the main challenge of opportunistic routing design for wireless multi-hop networks. Timer-based coordination is an efficient way to solve this problem. However this method leads to unnecessary duplicate transmission problem which will degrade the system performance. In the scenario where nodes are nonadjacent, the duplicate transmission problem...
For multiuser multiple-input multiple-output (MU-MIMO) systems with limited feedback in the downlink scenario, an end-to-end robust Tomlinson-Harashima Precoding (THP) transceiver design that incorporates receiver combining and transmit precoder is proposed based on sum mean squared error (SMSE) minimization. The channel state information (CSI) available at the transmitter for precoding is the quantized...
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