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This paper provides a methodology to study the PHY layer vulnerability of wireless protocols in hostile radio environments. Our approach is based on testing the vulnerabilities of a system by analyzing the individual subsystems. By targeting an individual subsystem or a combination of subsystems at a time, we can infer the weakest part and revise it to improve the overall system performance. We apply...
Ultra-Dense Networks (UDNs) are Heterogeneous Networks (HetNets) that deploy a high density of small cells over-laying the traditional macro cells. If several Long Term Evolution (LTE) layers share the available spectrum, assigning the Physical Cell Identities (PCIs) becomes complicated due to the density and the diversity of the network. Since different layers can be managed by different Network...
Abstract-Unlicensed LTE system holds high potential to effectively offload data/video traffic from the crowded licensed band. Previous effort of deploying LTE in the unlicensed band (e.g. license-assisted access LAA) relies on one or more LTE carriers in the licensed band, and may not be desired in certain scenarios. This paper studies a new technology of utilizing LTE directly in an unlicensed band,...
The overlaid cell structure, in which a large number of small cells are deployed in a macro-cell coverage area, is considered to be a promising approach in order to accommodate rapidly increasing mobile data traffic. In the overlaid cell structure, eICIC (enhanced Inter-Cell Interference Coordination) is an essential technique to avoid the interference between the macro cells and the small cells when...
LTE/LTE-A networks have been successfully providing advanced broadband services to millions of users worldwide. Lately, it has been suggested to use LTE networks for mission-critical applications like public safety, smart grid and military communications. We have previously shown that LTE networks are vulnerable to Denial-of-Service (DOS) and loss of service attacks from smart jammers. In this paper,...
DC (Dual Connectivity) and D2D (Device to Device) are two most promising methods to address huge traffic challenges in extreme dense network. In this paper, we investigate the researches and developments on DC and D2D in 3GPP (Third Generation Partnership Project). DC refers to the operation where some UE consumes radio resources provided by at least two different network points connected with non-ideal...
As professional mobile radio (PMR) networks evolve to a new generation based on Long Term Evolution (LTE), a new direct communication mode needs to be developed. Not only in PMR networks, but the increase of proximity services due to the explosion of the internet of things bring us to a new communication paradigm. The PMR users have very specific requirements and one of those is the ability to communicate...
In LTE, the Physical Control Format Indicator Channel (PCFICH) is a downlink control channel that indicates the number of OFDM symbols used by the primary downlink control channel in each sub frame. Even though the PCFICH only carries two bits of control information, it is essential to the operation of LTE. Since the PCFICH is a vital physical channel that only occupies a small fraction of the downlink...
Physical layer network coding (PNC) has recently attracted attention in wireless relay system. With PNC, the destructive effect of interference in wireless networks can be eliminated and the capacity of networks can be boosted significantly. However, synchronization is always considered as an outstanding issue which causes performance penalty on PNC. In [7], the impact of imperfect synchronization...
Time synchronization in a large network of small cells enables efficient interference management as well as advanced transmission techniques which can boost the network throughput. In this paper, we focus on the distributed initial synchronization problem and propose different solutions aiming at reducing the residual asynchronous interference while limiting the number of large timing reconfigurations...
The 5th generation (5G) of mobile radio access technologies is expected to become available for commercial launch around 2020. In this paper, we present our envisioned 5G system design optimized for small cell deployment taking a clean slate approach, i.e. removing most compatibility constraints with the previous generations of mobile radio access technologies. This paper mainly covers the physical...
In this paper, we provide an overview on backhaul requirements in mobile networks featuring inter-site cooperation. We consider a heterogeneous deployment, where small cells are embedded into macro-cells. For reducing inter-cell interference, we consider intra- and inter-site joint transmission (JT)-coordinated multi-point (CoMP) in fully flexible cooperation clusters. Backhaul traffic for a macro-cell...
Accurate channel estimation for multiple cells is essential in downlink coordinated multi-point (CoMP) transmission/reception. Therefore, this paper investigates a technique to improve the channel estimation for downlink CoMP in Long-Term Evolution (LTE)-Advanced. Particularly, the performance of data signal muting, i.e., muting data signals that collide with the channel state information reference...
OFDM (Orthogonal Frequency Division Multiplexing) has been chosen as the air interface technique for LTE (Long Term Evolution) standard. Furthermore, CA (Carrier Aggregation) is defined by 3GPP (the 3rd Generation Partnership Project) to support wide-bandwidth transmission. However, OFDM system is sensitive to synchronization errors generated by multipath delay, Doppler shift and oscillator instability...
The next generation of wireless networks (e.g., Long Term Evolution (LTE)and WiMAX) use multiple techniques to improve channel spectral efficiencies. In this paper we focus on one such technique, namely Coordinated Beam Switching (CBS). With CBS, each sector determines a sequence of beams (possibly with repetitions) over which it continuously cycles. Each sector independently determines its beam pattern...
Long Term Evolution (LTE) is the latest step towards the 4th generation (4G) of radio technologies designed to increase the capacity and speed of mobile communications. To support Multimedia Broadcast/Multicast Services (MBMS), LTE offers the possibility to transmit Multimedia Broadcast multicast service over a Single Frequency Network (MBSFN), where a time-synchronized common waveform is transmitted...
Along with LTE-Advanced system and standardization investigation progress, the requirement for verifying relevant key technologies become more and more urgent. This article summarizes the progress of Huawei 4G Test-bed “HEART” (Huawei Experimental Advanced Radio Test-bed). CoMP technology is considered as a launch point to build up this test-bed competence. Some initial analysis and results are addressed...
In Frequency Division Duplex (FDD) systems or Time Division Duplex (TDD) systems with perfect Uplink (UL)/Downlink (DL) alignment, all UL transmissions receive interference only from other UL links and vice versa. However, take into consideration one of the most important benefits that TDD offers, i.e., dynamic UL/DL switching points, the UL and DL transmission can be misaligned. This means UL might...
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