Cellular Mobile Systems Research Articles

A Optimum Resource Allot for Data in Code Division multiple access Contrary Link

The optimum resource apportionment standpoint is studied for non-real-time users CDMA (code division multiple access) overturn link. A resource apportionment standpoint of concern includes channel coding, out strectching gain control and power allocation under the conventional receive operation. The restriction in the optimization include peak transmit power of the mobile station, total received power at the base station and QoS in the form of minimum SINR (Signal-toInterference-plusNoise-Ratio) for each user. The coding and flattening gain control can be share from the power apportionment strategy. Our results show that the optimal power allotment standpoint depends on the purpose function: avaricious standpoint is optimal to maximize the sum of throughput from each user, whereas a fair standpoint is optimal to maximize the product of throughput from each user. A unified approach is taken to derive the optimal policies, and it can also be applied to other power apportionment problems in CDMA (code division multiple access) reverse link. Numerical results of the channel volume which can be held are presented for both objectives along with the effect of QoS constraints Code division multi access, information rates land(arrive on the ground, alight) mobile radio cellular systems, nonlinear programming resource (source of wealth) management.

Fast Handover Pre-Authentication Protocol in 3GPP-WLAN Heterogeneous Mobile Networks

The demand of ubiquitous communications drives the development of advanced mobile technologies. Meanwhile, recent increases in mobile data usage and the emergence of new IP service applications constitute the motivation to integrate 3GPP cellular mobile systems with broadband WLANs. Since 3GPP and WLAN systems complement each other in terms of infrastructure and network coverage and bandwidth, 3GPP-WLAN Heterogeneous Mobile Networks based on the 3GPP-based Home Network (3GHN) are proposed for meeting the growing demands in high-speed data access on any mobile devices. However, heterogeneous radio access technologies and architectures lead to many interworking issues, such as network transparency, security mechanism, seamless handover, and quality of service. Among of them, security and handover are the major motives to ensure the confidentiality, reliability and continuity of services in 3GPP-WLAN Heterogeneous Mobile Networks. This paper proposes fast handover pre-authentication protocol to reduce the handover authentication latency and authentication signaling overhead during the whole handover session. The proposed protocol supports Intra-Domain Handover Pre-Authentication (Intra-HO Pre-Auth) and Inter-Domain Handover Pre-Authentication (Inter-HO Pre-Auth) for preauthenticating the Mobile User (MS) prior to performing an Inter-domain Handover (Inter-domain HO)/Intra-domain Handover (Intra-domain HO) process. Meanwhile, the reduction in retrieving new Authentication Vector sand key sets from the Home Location Register/Home Subscriber Service/Authentication Center in 3GHN achieves for minimized redundant authentication signaling transactions between 3GPP domains and WLAN domains. In addition, this paper provides simulation results which show that the proposed Intra-HO Pre-Auth achieves 49% handover authentication performance improvement compared to EAP-AKA, and the proposed Inter-HO Pre-Auth achieves 26% handover authentication performance improvement as well.

Comparative Analysis of Feeding Techniques for Micro strip Patch Antenna and Smart Antenna Applications in Mobile Communication

This paper describes two folds. First it describes comparative analysis of different feeding techniques for microstrip patch antenna wireless applications. Where it covers two broad categories of feeding approach - contracting (coaxial and microstrip feeds) and non-contracting (aperture coupling and proximity coupling feeds). Today as smart antenna has emerged as an auspicious technique to improve the performance of cellular mobile system. In second section authors propose a MIMO structure ,consist of multiple antenna elements and its application in mobile communication with the key characteristics features, benefits, drawbacks, types of smart antennas and their working mechanism..

Securing spectrum through the ITU to fuel the growth of next-generation wireless technologies

Mobile data traffic is increasing exponentially and the ability of mobile broadband (MBB) technologies, such as Long Term Evolution-Advanced (LTE-A), to meet this demand depends on the availability of spectrum beyond that which is currently available to cellular mobile systems. This additional spectrum will be needed even considering the gains that will be delivered by LTE and LTE-A's higher spectral efficiency and the use of cell densification. Allocating and making spectrum available on a global basis is a complex process that is managed by the International Telecommunication Union (ITU) on a worldwide scale. Alcatel-Lucent and the wider mobile industry are working to harmonize this spectrum as much as possible to improve economies of scale for mobile broadband technologies and products. This paper describes the current “spectrum crunch,” the spectrum allocation process, steps being taken to make more effective use of available spectrum, and the challenges in making additional spectrum available for the success of next-generation wireless networks.

Application Analysis of IOT Based on Beidou Navigation System

With the governments strongly support and promotion, IOT (Internet of Things) has become popular in our life nowadays. In order to build China national IOT application technology, in this paper, IOT application architecture based on Beidou navigation system is presented and analyzed in detail. And the IOT network layer, which consists of wireless sensor network, cellular mobile communication network and Beidou navigation system, is mainly expounded. This architecture not only expands coverage area of IOT, but also enhances reliability and economical efficiency of the whole IOT system. Thereby, it can bring more new applications in IOT field.

Network coding-aware cooperative relaying for downlink cellular relay networks

In this paper, we first overview some traditional relaying technologies, and then present a Network Coding-Aware Cooperative Relaying (NC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> R) scheme to improve the performance of downlink transmission for relay-aided cellular networks. Moreover, systematic performance analysis and extensive simulations are performed for the proposed NC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> R and traditional relaying and non-relaying schemes. The results show that NC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> R outperforms conventional relaying and non-relaying schemes in terms of blocking probability and spectral efficiency, especially for cell-edge users. Additionally, the location selections for relays with NC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> R are also discussed. These results will provide some insights for incorporating network coding into next-generation broadband cellular relay mobile systems.

Performance of carrier frequency synchronization for OFDM-based mobile cellular systems over time selective fading channels

This paper evaluates the performance of a cell-specific reference signal (RS)-assisted residual carrier-frequency offset (CFO) detection scheme for a long-term evolution (LTE) downlink in a time-varying channel. Channel variations severely degrade the performance of OFDM by introducing both a complicated multiplicative distortion and an additive inter-carrier interference. Taking into consideration the effect of time-variant fading channels, an analytical closed-form expression of the mean square error (MSE) of the post-FFT CFO detection scheme is derived. The analytical expression is verified through simulations using the parameters of the LTE standard.

A Technique for Geographical Positioning Planning and RF Power Calculation of Radio Base Stations Using Geoprocessed Images

In this paper, a new patent technique was developed to support the geographical positioning planning and RF power calculation of Radio Base Stations (RBS) for the Cellular Mobile Systems using geoprocessed images of a mountain urban environment. The region of study is a neighborhood of Belo Horizonte City, in Minas Gerais State, Brazil. The mountain urban environment was considered in order to map the electromagnetic waves propagation for better coverage of cellular mobile service having the frequency band range of 800-900 MHz. The contributions of this research are: the implementation of a Geographic Information System (GIS) in order to exploit and simulate possibilities of geopositioning for the RBS to guarantee efficient area coverage, along with a quality service for radiofrequency system; the evaluation of power prediction levels for radiofrequency signals using Okumura-Hata propagation model, in order to obtain an optimum algorithm to register the geopositioning of the RBS. As a result, the minimum distances among fifteen suggested RBS and their coverage mapping regions are shown.

Multicell cooperation for the 4G mobile cellular systems [Message from the Editor-in-Chief

This issue features a feature topic on Multicell Cooperation, which contains 11 excellent papers collected by our Guest Editors, Ekram Hossain and Zander (Zhongding) Lei. They worked extremely hard to edit this feature topic due to a fairly large number of submissions to the Call for Papers.

Interference management through CoMP in 3GPP LTE-advanced networks

Intercell interference management has become a critical issue for future cellular mobile systems. Coordinated multipoint transmission/reception, or CoMP, is an effective way of managing intercell interference, and has been regarded as a key technology of LTE-Advanced. This article first provides an overview of downlink CoMP techniques specified in 3GPP LTE Rel-11, which mainly focuses on transmission schemes, channel state information reporting, interference measurement, and reference signal design. Then uplink CoMP is discussed in brief as most of the coordination gain can be achieved by implementation with little standardization support. Evaluation results are provided to show the efficiency of CoMP. The challenges as well as possible solutions for future CoMP standardization are also discussed.

An efficient user scheduling scheme for downlink Multiuser MIMO-OFDM systems with Block Diagonalization

The combination of multiuser multiple-input multiple-output (MU-MIMO) technology with orthogonal frequency division multiplexing (OFDM) is an attractive solution for next generation of wireless local area networks (WLANs), currently standardized within IEEE 802.11ac, and the fourth-generation (4G) mobile cellular wireless systems to achieve a very high system throughput while satisfying quality of service (QoS) constraints. In particular, Block Diagonalization (BD) scheme is a low-complexity precoding technique for MU-MIMO downlink channels, which completely pre-cancels the multiuser interference. The major issue of the BD scheme is that the number of users that can be simultaneously supported is limited by the ratio of the number of base station transmit antennas to the number of user receive antennas. When the number of users is large, a subset of users must be selected, and selection algorithms should be designed to maximize the total system throughput. In this paper, the BD technique is extended to MU-MIMO-OFDM systems and a low complexity user scheduling algorithm is proposed to find the optimal subset of users that should transmit simultaneously, in light of the instantaneous channel state information (CSI), such that the total system sum-rate capacity is maximized. Simulation results show that the proposed scheduling algorithm achieves a good trade-off between sum-rate capacity performance and computational complexity.

An EM Algorithm-Based Disintegrated Channel Estimator for OFDM AF Cooperative Relaying

The cooperative orthogonal frequency-division multiplexing (OFDM) relaying system is widely regarded as a key design for future broadband mobile cellular systems. This paper focuses on channel estimation in such a system that uses amplify-and-forward (AF) as the relaying strategy. In the cooperative AF relaying, the destination requires the individual (disintegrated) channel state information (CSI) of the source-relay (S-R) and relay-destination (R-D) links for optimum combination of the signals received from source and relay. Traditionally, the disintegrated CSIs are obtained with two channel estimators: one at the relay and the other at the destination. That is, the CSI of the S-R link is estimated at relay and passed to destination, and the CSI of the R-D link is estimated at destination with the help of pilot symbols transmitted by relay. In this paper, a new disintegrated channel estimator is proposed; based on an expectation-maximization (EM) algorithm, the disintegrated CSIs can be estimated solely by the estimator at destination. Therefore, the new method requires neither signaling overhead for passing the CSI of the S-R link to destination nor pilot symbols for the estimation of the R-D link. Computer simulations show that the proposed estimator works well under the signal-to-noise ratios of interest.

Performance Evaluation of Cellular Radio System with Directed Retry

In this paper the arrival of calls (new and handoff) in personal communications services (PCS) network are modeled according a Markov Arrival Process (MAP). The purpose of our study is to improve the performance of the cellular mobile system by using directed retry scheme. The cut of priority scheme have also been applied to provide priority to handoff calls. Here we construct tractable model using fixed channel assignment scheme with priority to handoff voice calls. The proposed directed retry scheme with finite buffering for handoff voice calls is useful for improving the handoff blocking probability of handoff voice calls. The integrated traffic model has been constructed for finite population. FIFO fashion has been taken for arrival calls. The balking behavior of the calls has also been taken into consideration. The expressions for various performance indices viz. blocking probabilities for different traffic, overall blocking probability, offered carried load etc. are determined for above model. It is clear from the analytical results that by increasing overlapping area and retrying in overlapping area, a substantial improvement can be achieved.

Main enablers for advanced interference mitigation

ABSTRACTThe vision of an interference‐free or interference‐exploiting mobile cellular radio system has attracted lots of research groups. It led to several 3GPP long term evolution coordinated multipoint transmission studies and working items. So far, the results achieved are still far from theoretical performance as expected from network‐wide cooperation. In reality, small to moderate gains will be easily lost in case of realistic channel estimation and feedback assumptions. Therefore, the European Union founded project ARTIST4G had a three‐fold goal: leveraging considerable system level gains in combination with an effective channel estimation and a low rate feedback scheme. One main enabler is the so‐called partial coordinated multipoint plus cover shift concept of overlapping cooperation areas approaching user centric clustering. ‘Simple’ but powerful is a novel interference floor shaping technique based on cooperation area specific vertical antenna tilting and power allocation. An enhanced scheduling strategy turns signal to interference and noise into spectral efficiency and coverage gains. For overcoming channel state information outdating and simultaneously minimizing feedback overhead, a model‐based channel prediction concept is proposed reporting location instead of channel state information. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Performance analysis of a distributed fixed-step power control algorithm via window concept in cellular mobile systems

In cellular mobile systems, the received carrier-to-interference ratio (CIR) can be maintained within the desirable range provided that the path gain remains approximately constant over a number of consecutive power control steps. However, when channels suffer short-term fading, it is not clear whether existing power control algorithms remain convergent. This paper proposes a distributed fixed-step power control algorithm with binary feedback via window concept for cellular mobile systems. The essence of the proposed algorithm is that the power control step size can be regulated by window size. The performance of the proposed scheme is analyzed in short-term fading channels. A sufficient condition for system stability is derived using a simple received CIR model and a power control window. It is shown herein that the bound of the received CIR of each user varies as a function of the target CIR, the size of the power control step and the link gain. The analysis and simulation results show that if the step size is properly set according to the window size, the proposed algorithm can achieve a small convergence region and a fast convergence rate.

Admission control policy for adaptive multirate multiservices in cellular systems

Forced termination of connections during handover and blocked connection initiation are annoying from the perspective of multiservice cellular system users. Previous studies have shown that an admission control policy reduces the dropping probability to a much lower level but at the cost of raising the blocking probability to a higher level. As an alternative for reducing both blocking and dropping probabilities, we make use of the Adaptive Multirate (AMR) scheme, which is a well-known real-time streaming coding technique. For an example of AMR technique, a video source is encoded into multiple independent descriptions. A cellular device, depending on its available computing and network resources, joins different descriptions to meet performance requirements. The base layer is received and the enhancement layer(s) are abandoned if the cellular capacity is insufficient for high-quality video. Mobile cellular devices currently obtain basic video quality at a lower frame rate. AMR services can substantially improve the degree of user satisfaction and guarantee the connection-level quality of service (QoS) for different multimedia. In cellular systems, the QoS requirements of different services require a connection admission control (CAC) that limits the number of connections in each access network. Therefore, we focus on the CAC and connection-level QoS of multiservice traffic using adaptive coding in mobile cellular systems. We initially analyzed our CAC policy in a multiservices cellular system by formulating the CAC policy functions, arrival rate, departure rate, blocking probability, and dropping probability of the multiservices, before we derived the connection-level QoS and verified it by simulation. The adaptive coding of multiservices traffic has a significant impact on the connection-level QoS in multiservice cellular systems. Our method decreased the blocking and dropping probabilities by adapting multirate services while users were roaming. Mobile cellular operators providing AMR services could apply our CAC to fulfill the quality requirements of the user experience and also improve the connection-level QoS.

A PN Sequence Generator based on Residue Arithmetic for Multi-User DS-CDMA Applications

The successful use of CDMA technology is based on the construction of large families of encoding sequences with good correlation properties. This paper discusses PN sequence generation based on Residue Arithmetic with an effort to improve the performance of existing interference-limited CDMA technology for mobile cellular systems. All spreading codes with residual number system proposed earlier did not consider external interferences, multipath propagation, Doppler effect etc. In literature the use of residual arithmetic in DS-CDMA was restricted to encoding of already spread sequence; where spreading of sequence is done by some existing techniques. The novelty of this paper is the use of residual number system in generation of the PN sequences which is used to spread the message signal. The significance of cross-correlation factor in alleviating multi-access interference is also discussed. The RNS based PN sequence has superior performance than most of the existing codes that are widely used in DS-CDMA applications. Simulation results suggest that the performance of the proposed system is superior to many existing systems. Keywords—Direct-Sequence Code Division Multiple Access (DSCDMA), Multiple-Access Interference (MAI), PN Sequence, Residue Number System (RNS).

Multipath Interference Cancellation in MIMO Mobile Cellular system

Wireless network widely used today include, cellular network, wireless mesh network (WMNs), wireless local area network and personal area network. The increasing demand for these networks has turned spectrum into a precious resource. For this reason, there is always a need for methods to pack more bits/Hz. A particular solution is to use multiple antenna at both transmitter and receiver side. Such a system is called multiple-input multiple-output (MIMO) system. In real propagation environment of cellular communication, channel reuse will cause the co-channel interference which will degrade the MIMO channel performance. The interference cancellation (IC technology) can handle efficiently the cochannel interference. In this paper comparison computer simulation for zero forcing successive interference cancellation (ZF-SIC) minimum mean square error (MMSE equalizer) and maximum likelihood (ML) for two transmitting and two receiving antenna is shown.

Investigation of Doppler Effects on high mobility OFDM-MIMO systems with the support of High Altitude Platforms (HAPs)

The merging of Orthogonal Frequency Division Multiplexing (OFDM) with Multiple-input multiple-output (MIMO) is a promising mobile air interface solution for next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. This paper details the design of a highly robust and efficient OFDM-MIMO system to support permanent accessibility and higher data rates to users moving at high speeds, such as users travelling on trains. It has high relevance for next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. The paper begins with a comprehensive literature review focused on both technologies. This is followed by the modelling of the OFDM-MIMO physical layer based on Simulink/Matlab that takes into consideration high vehicular mobility. Then the entire system is simulated and analysed under different encoding and channel estimation algorithms. The use of High Altitude Platform system (HAPs) technology is considered and analysed.

Experimental Analysis of Xie and Kuek's Traffic Model with Handoff Scheme in Wireless Networks

Mobility becomes a distinct feature for a wireless mobile cellular system. For the traffic which is non stationary and is away from the base station, the chances of a call to be handed off are increased. In urban mobile cellular systems, especially when the cell size becomes relatively small, the procedure has a significant impact on system performance. Blocking probability of originating calls and the forced termination probability of ongoing calls are the primary criteria for indicating this performance. In this paper, we report our recent work on closed form solutions to the blocking probability followed by dropping probability in wireless cellular networks with . First, we develop a performance model of a cell in a wireless network where the effect of