Mobile Communication Environment Research Articles

A Provable Billing Protocol on the Current UMTS

This paper proposes a simple method that equips UMTS-based telecom companies with a mechanism to prove the records on mobile users' phone bills. In the history of mobile phone communication, we have seen countless unsettled disputes where the mobile user disagrees with the telecom company either on the calling time or on the duration, or even on whether or not a call was actually made. In this paper, a provable billing protocol will be presented that can effectively solve disagreements between the two parties. Equipped with a non-repudiation function, the proposed protocol enables the service provider to hold on to the solid proofs as to exactly when and to which number a mobile phone user made a call so that the mobile user cannot deny; at the same time, the mobile user also gets to have his/her own share of proofs as to when and how the mobile services were accessed, so that the bill can be double checked to make sure nothing goes wrong. And, to make it even better, this new protocol is perfectly compatible with the standard UMTS protocol and is therefore readily applicable to the current mobile phone communication environments.

A Converged Charging Framework for Mobile Voice and Data Applications

The evolution of an integrated mobile communication environment enables service deployment and content delivery offered by independent providers through heterogeneous network infrastructures. In a few months, a mobile user will be able to access value added services through several wireless public access networks (i.e., 3G cellular, Wireless LAN or WAN) belonging to the same or different operators and simultaneously use multiple different services at the same time. In this scenario there is a strong need for a common charging and billing scheme enhancing access flexibility and encouraging services and network convergence. We propose, starting from an AAAbased 3G-WLAN roaming/interworking paradigm, a unified “one stop” charging scheme, according to which the customers will receive a single itemized bill for all consumed services regardless of the providing party and access technology. Such a platform can become very helpful for the homogeneous development of charging functionalities for new-generation integrated mobile services.

Random security scheme selection for mobile transactions

AbstractSecurity in a mobile communication environment is always a matter for concern, even after deploying many security techniques at device, network, and application levels. The end‐to‐end security for mobile applications can be made robust by developing dynamic schemes at application level which makes use of the existing security techniques varying in terms of space, time, and attacks complexities. In this paper we present a security techniques selection scheme for mobile transactions, called the Transactions‐Based Security Scheme (TBSS). The TBSS uses intelligence to study, and analyzes the security implications of transactions under execution based on certain criterion such as user behaviors, transaction sensitivity levels, and credibility factors computed over the previous transactions by the users, network vulnerability, and device characteristics. The TBSS identifies a suitable level of security techniques from the repository, which consists of symmetric, and asymmetric types of security algorithms arranged in three complexity levels, covering various encryption/decryption techniques, digital signature schemes, and hashing techniques. From this identified level, one of the techniques is deployed randomly. The results shows that, there is a considerable reduction in security cost compared to static schemes, which employ pre‐fixed security techniques to secure the transactions data. Copyright © 2008 John Wiley & Sons, Ltd.

Privacy-enhanced Key Recovery in mobile communication environments

Generally, in mobile communication environments, Wireless Authentication and Key Establishment (WAKE) protocols are essential for secure information transmission. Key Recovery (KR) protocols, including WAKE protocols, can enable an authorized third party to gain access to encrypted message data under certain lawful circumstances. However, it is not easy to construct secure and strongly privacy-preserved KR protocols for mobile communication environments due to mobile hardware resources' limitation. In this paper, we propose a security-enhanced KR protocol and then we construct a privacy-enhanced KR protocol, which is based on the security-enhanced KR protocol, for protecting users' location privacy.

Editorial: Special issue on mobile P2P networking and computing

Peer-to-Peer networking first emerged as an overlay technique to support distributed file sharing over the Internet. Since then, P2P networking and computing have gradually evolved into a system framework that delivers a broad range of distributed and scalable resource discovery and sharing applications including efficient search of data items and people using context/key based routing, application level multicast, redundant storage, video streaming, etc. Striving for automated formation, distributed operation and effective resource sharing, peers form self-organizing overlay networks and offer services beyond the traditional client-server paradigm of Internet by entrusting symmetry in roles and requiring no or fewer pre-established servers. Today, mobile end devices are one of the major participants in information gathering, processing, dissemination and consumption. Supporting the P2P networking and computing paradigm in this ever growing mobile communications environment has become an appealing idea. The key attraction of the Mobile P2P (MP2P) paradigm is its ability to scale without requiring expensive and manually configured servers, and to sustain failure points through automatic recovery of a fully distributed structure. Compared with wired networks, it is generally more difficult to set up and maintain centralized servers in some mobile networks, such as in the Mobile Ad hoc Network (MANET). It may also be generally possible to harvest efficiency gains through sharing applications and contents among peer mobile end devices directly rather than backhauling them to a centralized server in the fixed backbone network. Though the P2P paradigm may naturally suit well the distributed and dynamic wireless communications environment, support of MP2P is particularly challenging considering the special characteristics of the mobile networks. The highly variable connectivity, frequent disconnection, locationdependency, energy and resource constraints, diversity in wireless end devices and as well the carrier-grade performance requirements when offering business level applications bring about some critical issues in facilitating the MP2P paradigm. The mobility of the users may increase dramatically the churn in the peer systems to engender extra overhead when employing P2P overlay protocols. The limited bandwidth and constrained battery resource available to the wireless device aggravate the hindrance and may even render the P2P overlay mechanism infeasible in operation. Due to resource limitations, mobile peers can be inclined to the selfish freerider behaviour in data sharing and downloading. The Peer-to-Peer Netw Appl (2009) 2:179–181 DOI 10.1007/s12083-009-0040-z

An Unequal Error Protection System Using Trellis Coded Modulation and an Adaptive Equalizer

We proposed an unequal error protection (UEP) scheme using trellis coded modulation and an adaptive equalizer for use in mobile fading channel communication environments. We proposed a signal constellation to realize unequal error protection and showed its performance using computer simulations.

A NEW PROPOSAL CAPON BEAMFORMER FOR ANGULAR SPREADS ON DISTRIBUTED SOURCES IN A CELLULAR ENVIRONMENT

In this work, a new robust adaptive digital beamforming algorithm called Gaussian Robust Capon Beamformer (GRCB) is proposed, it is based on conventional Capon criteria and provides compensation of the steering vector errors through diagonal loading approach. This research was conducted assuming a critical scenario where a communication environment presents a high value of angular spread (AS>2 degrees) on signal of interest and in which other beamforming methods, including robust Capon algorithm can degrade their performance upon presenting the phenomenon of auto- cancellation of the signal of interest. Additionally, a study of the beamforming algorithms performance is discussed, based on Minimum Variance Distortionless Response (MVDR) method as well as its robust version; this study is conducted using a radio channel model with a Gaussian scatters distribution, around the signal of interest and typical angular spread values for difierent mobile communication environments. Finally, simulation results are shown where the performance of GRCB algorithm is compared with difierent approaches of Capon beamforming; it can be observed that using the proposed algorithm is possible to achieve a minimization in signal of interest degradation and a better isolation, regardless of interferers and noise levels.

Designing efficient proxy signature schemes for mobile communication

Proxy signature is an active cryptographic research area, and a wide range of literatures can be found nowadays suggesting improvement and generalization of existing protocols in various directions. However, from the efficiency view, many proposed proxy signature schemes in these literatures are not satisfying and cannot fit to the mobile communication. Therefore, there is a desire to design efficient proxy signature schemes. Based on Boneh et al.’s pairing-based short signature, this paper presents two proxy signature schemes. One is proxy-protected signature scheme, and the other is proxy aggregate signature scheme. Since both of them can achieve high efficiency, it is believed that they are specially suitable for mobile communication environment.

End-to-end adaptation scheme for ubiquitous remote experimentation

Remote experimentation is an effective e-learning paradigm for supporting hands-on education using laboratory equipment at distance. The current trend is to enable remote experimentation in mobile and ubiquitous learning. In such a context, the remote experimentation software should enable effective telemonitoring and teleoperation, no matter the kind of device used to access the equipment. It should also be sufficiently lenient so as to handle the rapidly evolving wireless and mobile communication environment. While the current Internet bandwidth allows remote experimentation to work flawlessly on fixed connections such as LANs, mobile users suffer from both the versatile nature of wireless communications and the limitation of the mobile devices. These conditions impose that the remote experimentation software should integrate adaptation features. For effective ubiquitous remote experimentation, it should ideally be guaranteed that the information representing the state of the remote equipment is rendered (to the end user) at the same pace at which it has been acquired, yet possibly at the cost of a somewhat minimal time delay between the acquisition and rendering phases. In this respect, an end-to-end adaptation scheme is proposed that explicitly handles the inherent variability of the connection and the versatility of the mobile devices considered in ubiquitous remote experimentation. Instead of relying on a stochastic approach, the proposed adaptation scheme relies on a deterministic mass-balance equivalence model. The effectiveness of the proposed adaptation scheme is demonstrated in critical conditions corresponding to remote experimentation carried out using a PDA over a Bluetooth link.

A Low-Power Multicarrier-CDMA Downlink Baseband Receiver for Future Cellular Communication Systems

In this paper, design and implementation of a baseband receiver integrated circuit (IC) for a downlink multi-carrier code-division multiple access (MC-CDMA) system are presented. This MC-CDMA system aims to provide higher data transmission capacity than the current wide-band CDMA systems in mobile cellular communication environments. The proposed chip provides a robust tracking mechanism for synchronization errors and an accurate channel estimation strategy to overcome the challenge of outdoor fast-fading channels. Besides, low-power and low-complexity architecture design techniques are adopted to satisfy mobile receiver needs. Experimental results of the designed baseband receiver integrated circuit demonstrate its superior system performance and great reduction in power consumption. The chip was fabricated in a 0.18-mum CMOS technology with a core area of 2.6 mm times 2.6 mm. It can support up to 21.7-Mbps uncoded data rate in a 5-MHz bandwidth. When running at 5.76 MHz, its power consumption is as low as 9.9 mW from a supply voltage of 1.1 V.

The Cameraphone and Online Image Sharing

The cameraphone and the cell phone together create a commercially exploitable mobile communications environment, yet there is evidence that the mobile communications industries find encouraging a c...

A CUSTOMIZABLE QOS STRATEGY FOR CONVERGENT HETEROGENEOUS WIRELESS COMMUNICATIONS

This article proposes a general customizable QoS scenario for heterogeneous wireless access network technologies. The scenario provides robust and flexible QoS support by adapting the amount of resources reserved for the characteristics of the wireless channel, as well as automatic reconfiguration mechanisms of the multimedia encoding rate and error-resilient techniques to adapt to the dynamic mobile communication environment. Two new scenarios, adaptive FEC and MAC-Lite, are introduced to the proposed scheme. These enable a maximizing of the overall performance of the wireless network. The appropriate interfaces within the core network are described for performing end-to-end QoS, which deliver network meters and exchange QoS parameters with the proposed intra and inter cross-layer approaches, including context transfer during handover. Each part, extended by the proposed method can be configured by the application and be independently implemented. To evaluate the proposed scheme, the QoS components were integrated into a trial platform that was built and simulations were then performed. The results demonstrate that the communication quality was significantly improved

Calculation of Spectral Efficiency for Estimating Spectrum Requirements of IMT-Advanced in Korean Mobile Communication Environments

In this paper, we analyze the algorithm of the methodology developed by ITU for the calculation of spectrum requirements of IMT-Advanced. We propose an approach to estimate user density using traffic statistics, and to estimate spectrum efficiencies using carrier-to-interference ratio distribution and capacity theory as well as experimental data under Korean mobile communication environments. We calculate the IMT-Advanced spectrum requirements based on the user density and spectral efficiencies acquired from the new method. In the case of spectral efficiency using higher modulation and coding schemes, the spectrum requirement of IMT-Advanced is approximately 2700 MHz. When applying a 2×2 multiple-input multiple-output (MIMO) antenna system, it is approximately 1500 MHz; when applying a 4×4 MIMO antenna system, it is approximately 1050 MHz. Considering that the development of new technology will increase spectrum efficiency in the future, the spectrum requirement of IMT-Advanced in the Korean mobile communication environment is expected to be approximately 1 GHz bandwidth.

Second order statistics of the signal in Ricean-lognormal fading channel with selection combining

Level crossing rate and average fade duration of signal envelope of selection diversity are numerically determined. Statistical characterization in fading and shadowing mobile radio communication environment are very useful and in this paper that is computed for Ricean fading channels with lognormal shadowing. The results are presented for independent identically distributed diversity branches when selection combining technique is used.

An intelligent agent approach to improving the coordination efficiency in the donor kidney distribution process

Kidney transplantation is an effective treatment for an end-stage renal disease. Donor kidneys need to be matched with appropriate patients, distributed and transplanted very quickly (less than 40 hr) in order to achieve optimal medical results. In this paper we analyse the bottlenecks in the current donor kidney distribution process and investigate how agent technology can be applied to improve this process. We propose a distributed multi-agent system operating in a mobile communication environment to assist transplant coordinators in coordinating with multiparties in this time-critical distribution process. A prototype system has been developed to demonstrate the feasibility of such a system.

Analysis of received‐level detection accuracy in DS‐CDMA systems

AbstractCellular mobile communications require the detection of received levels at mobile stations so that the positions of the mobile stations can be detected. Given that paths can be isolated in the broadband DS‐CDMA method, the technique generally used is RAKE reception, and improvements in detection accuracy due to the path diversity effect can be expected. This paper discusses the application to the DS‐CDMA technique of a method in which the average reception power is estimated from N reception levels (the true value) obtained by sampling at a certain time interval ΔT in a mobile communication environment in which the reception voltage changes dynamically as the mobile unit runs. First, we perform a theoretical analysis of the detection accuracy of the received level in a general reception model that simultaneously takes both antenna diversity and path diversity into consideration, and then we demonstrate the plausibility of the theoretical analysis by means of computer simulations. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(2): 58–71, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20217

Security flaws of remote user access over insecure networks

Remote user authentication based on passwords over untrusted networks is the conventional method of authentication in the Internet and mobile communication environments. Typical secure remote user access solutions rely on pre-established secure cryptographic keys, public-key infrastructure, or secure hardware. Recently, Peyravian and Jeffries proposed password-based protocols for remote user authentication, password change, and session key establishment over insecure networks without requiring any additional private- or public-key infrastructure. In this paper we point out security flaws of Peyravian–Jeffries’s protocols against off-line password guessing attacks and Denial-of-Service attacks.

Sports video summarization and adaptation for application in mobile communication

Sports video appeals to large audiences due to its high commercial potentials. Automatically extracting useful se- mantic information and generating highlight summary from sports video to facilitate users' accessing requirements is an important problem, especially in the forthcoming broadband mobile communication and the need for users to access their multimedia in- formation of interest from anywhere at anytime with their most convenient digital equipments. In this paper, a system to generate highlight summaries oriented for mobile applications is introduced, which includes highlight extraction and video adaptation. In this system, several highlight extraction techniques are provided for field sports video and racket sports video by using multi-modal information. To enhance users' viewing experience and save bandwidth, 3D animation from highlight segment is also generated. As an important procedure to make video analysis results universally applicable, video transcoding techniques are applied to adapt the video for mobile communication environment and user preference. Experimental results are encouraging and show the advantage and feasibility of the system for multimedia content personalization, enhancement and adaptation to meet different user preference and network/device requirements.

Spatial Fading Simulator Using a Cavity-Excited Circular Array (CECA) for Performance Evaluation of Antenna Arrays

SUMMARY In this paper we propose a novel spatial fading simulator to evaluate the performance of an array antenna and show its spatial stochastic characteristics by computer simulation based on parameters verified by experimental data. We introduce a cavity-excited circular array (CECA) as a fading simulator that can simulate realistic mobile communication environments. To evaluate the antenna array, two stochastic characteristics are necessary. The first one is the fading phenomenon and the second is the angular spread (AS) of the incident wave. The computer simulation results with respect to fading and AS show that CECA works well as a spatial fading simulator for performance evaluation of an antenna array. We first present the basic structure, features and design methodology of CECA, and then show computer simulation results of the spatial stochastic characteristics. The results convince us that CECA is useful to evaluate performance of antenna arrays.

3D autocorrelation coefficients of dipole antenna

An analytical expression is given for the 3D autocorrelation coefficient of a half-wavelength dipole antenna as a function of spatial separation in an isotropic scattering environment. Results are verified experimentally through measurements conducted in antenna anechoic chambers. The results closely match previously published work based upon measurements collected in a typical indoor mobile communication environment. It is recommended that the 3D autocorrelation coefficient model be used to gauge diversity antenna measurement systems.