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In this paper, a two-tier UMTS network is considered where a large number of randomly deployed Wideband Code Division Multiple Access (WCDMA) femtocells are laid under macrocells where the spectrum is shared. The co-channel interference between the cells may be a potential limiting factor for the system. We study the uplink of this hybrid network, and identify the critical scenarios that give rise...
IMT-Advanced systems are currently in their evaluation phase. Due to the complexity of all the integrated algorithms and the multidimensional variability of the wireless channels a system evaluation is not easy and only very few large enterprises have the manpower to construct software to simulate all relevant effects. Traditionally the effects of channel and physical layer algorithms have been studied...
Femtocells are low-power base stations which improve signal coverage in indoor environment. In order to deploy femtocells in macro cells, one of the essential issues is to evaluate the interferences towards the mobile users served by the macro cells. In this paper we mainly analyze the system performance of TD-SCDMA cellular radio network for HSDPA data services when operating femtocells. The fixed...
The IMT-Advanced standardization process is executed by International Telecommunications Union Radiocommunication Sector (ITU-R) to define requirements to the next 4-th generation mobile communication systems and certify technologies meeting these requirements. This work presents results of the IEEE 802.16m and 3GPP LTE Release 10 technologies evaluation obtained by the Russian Evaluation Group (REG)...
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...
Long Term Evolution (LTE), the next-generation network beyond 3G, is designed to support the explosion in demand for bandwidth-hungry multimedia services that are already experienced in wired networks. To support Multimedia Broadcast/Multicast Services (MBMS), LTE offers functionality to transmit MBMS over a Single Frequency Network (MBSFN), where a time-synchronized common waveform is transmitted...
The use of Hybrid ARQ in wireless networks is to provide fast re-transmits and to lower the overall error rate. The performance of HARQ schemes is a well studied field, with many results to draw from in the literature. An area that is less researched is what impact Hybrid ARQ has on LTE systems. We are, specifically, interested in looking at the system delay, but also at how HARQ behaves when used...
In this paper, we evaluate the performance of UMTS (Universal Mobile Telecommunication System) downlink system in vicinity of a healthcare system. We assume that the healthcare system is a body area network (BAN) system which is based on UWB (Ultra Wide Band) technology. So, the effect of UWB BAN system on UMTS system is investigated by simulation. From the simulation results, we found that the UMTS...
In this paper, a generalized model is proposed to analyze the impact of propagation environment and velocity on the handover performance of user equipment (UE) for long term evolution (LTE) systems. An adaptive time window is defined within the generalized model, to provide additional flexibility to perform handover procedure over conventional reference signal received power (RSRP) and reference signal...
3GPP LTE-Advanced has adopted the coordinated multi-point transmission and reception (CoMP) technique as a new promising scheme. The CoMP technique can reduce the inter-cell interference (ICI) effectively, which has a great potential for enhancing cell-edge user data rate/coverage and cell throughput significantly. For downlink CoMP, most research work mainly focuses on precoding schemes with explicit...
In this paper, we address the problem of interference mitigation with data pre-processing in the 4G uplink systems, and propose to use the Grubbs/Wright algorithm to detect and remove the interference contaminated data. The Markov algorithm is also applied to correct the system errors. The pre-processed data are used for channel estimation and data detection in base stations.
In order to fully benefit from multiple-input multiple-output (MIMO) channels, multiuser techniques are adopted in the 3rd generation partner project (3GPP) long term evolution (LTE) downlink system. The core task of multiuser MIMO system is to suppress multiuser interference and enhance the signal to interference plus noise ratio (SINR). As a classical MIMO scheme, block diagonalization (BD) algorithm...
The role of uplink power control is to suppress interference. Power control refers to set output power levels of transmitters, base stations in the downlink and User Equipment (UE) in the uplink. In this paper the performance of 3GPP Long Term Evolution (LTE) closed loop power control combined with fractional path loss compensation factor is evaluated by simulating the effects of open loop error,...
One of the most important challenges is how to manage inter-cell interference. Special care has to be taken regarding voice traffic which has more strict requirements on delay and packet loss. The goal of inter-cell interference coordination schemes is to decrease inter-cell interference and get higher cell throughput, so we evaluated the performance of inter-cell interference coordination schemes...
Smart antennas have received increasing interest due to its capability for improving the performance of wireless radio systems. In this work we studied the throughput maximization in a CDMA 1xEV-DO cellular system when a smart antenna array is implemented. We focus in the downlink of the CDMA cellular system and consider a packet data direct-sequence code division multiple access (DS-CDMA). We show...
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...
Digital Video Broadcasting - Satellite services to Handhelds (DVB-SH) and UMTS networks are located in very close portions of the electromagnetic spectrum and can thus operate in adjacent frequency bands. Consequently, an assessment of their coexistence is of primary importance. This paper presents an investigation into the reciprocal interference between the two systems. A method to characterize...
In view of the new feature after introducing the relay nodes (RNs) into the conventional cellular networks, a novel soft frequency reuse (SFR)-based inter-cell interference coordination (ICIC) scheme is proposed in the relay enhanced cellular networks. On the basis of original ICIC scheme for conventional cellular network, RNs in the proposed SFR scheme reuses part of neighboring cell-edge bands to...
This paper defines a synthetic non-regular Springwald network layout which is easy to take into use in cellular network system simulations. The performance of the non-regular layout was compared with two regular 3GPP simulation scenarios. The benefit of the non-regular layout is that it reflects better the live network deployments and therefore results in more realistic benchmarking metrics. The results...
The capacity and coverage area of a cell may vary due to changed environment, insertion or deletion of base stations, or malfunctioning base stations, and wrong parameter selection in the network planning phase. Suboptimal capacity and coverage area leads to the waste of network resources and the lower quality. Reacting on the changed situation manually is very expensive and time consuming. Therefore,...
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