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Mobile Services (mobile + services)

Distribution by Scientific Domains
Engineering75%

Selected Abstracts

Optimised spreading code redistribution PAPR reduction technique for MC-CDMA systems

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2009
Lin Yang
Multicarrier code division multiple access (MC-CDMA) is one of the most promising techniques considered for future broadband mobile services. However, the high peak to average power ratio (PAPR) problem associated with MC-CDMA systems can significantly degrade the power efficiency at the transmitter. This paper proposes an efficient PAPR reduction technique for the downlink of MC-CDMA systems. It regards the order of the CDMA spreading codes as an extra degree of freedom and exploits it to effectively reduce the PAPR of the signal. The proposed technique requires only slight modification to the MC-CDMA base station and negligible complexity to the mobile terminals. Both lightly loaded and fully loaded systems are examined when using the orthogonal sets of Walsh,Hadamard (WH) and Golay complementary sequences (CSs). It will be demonstrated that the proposed technique achieves significant PAPR reduction with low system complexity at both transmitter and receiver. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Antenna diversity for DVB-S2 mobile services in railway environments

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2007
S. Cioni
Abstract This paper evaluates the applicability of the DVB-S2 standard in railway environments, where the most peculiar impairment is the periodic deep fading caused by power-supply arches distributed along the rail tracks. This effect induces a link loss every time the train antenna undergoes a power arch and cannot be counteracted with transmission power. Therefore, we propose and investigate the use of antenna diversity on the train. Simulation and semi-analytical results show that second-order diversity suffices to remove the packet error floor observed in the case of a single receiving antenna, thus enabling the application of DVB-S2 to this harsh environment. Copyright © 2007 John Wiley & Sons, Ltd. [source]

A DVB/Inmarsat hybrid architecture for asymmetrical broadband mobile satellite services

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2006
Bjørn Roger Andersen
Abstract In order to bridge the gap, both regulatory and technologically, between offering mobile satellite services at L-band today and broadband mobile services at C-band, Ku-band or Ka-band in the future, a short-term solution is foreseen. Therefore, a DVB/Inmarsat hybrid service offering bi-directional asymmetrical satellite connectivity, with a broadband receive channel at Ku-band based on DVB-S, and with a transmit channel at L-band based on Inmarsat Mobile Packet Data Service, has successfully been developed, implemented and tested. The article focuses on the rationale for, and a technical solution, and how this can be evolved to support use of Inmarsat Broadband Global Area Access as transmit channel at L-band. There are no regulatory issues associated with global operation of such a system, and the users can access the services using cost-efficient off-the-shelf equipment, since the well established Inmarsat and DVB standards are utilized. The system has proved its feasibility to offer services like Internet access, email access, fast file transfers, and IP streaming of audio and video, in addition to the traditional Inmarsat services. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Comparing the perceived value of information and entertainment mobile services

PSYCHOLOGY & MARKETING, Issue 8 2008
Minna Pihlström
The importance of perceived value in customer decision making is well known. However, few studies assess empirically the direct effects of various perceived value dimensions on post-purchase behavior. This article examines differences between information and entertainment mobile content service users in how their value perceptions influence intentions to repurchase, intentions to spread positive word of mouth, and willingness to pay a price premium. The direct effects of four value dimensions are analyzed: monetary, convenience, emotional, and social value. Within this study we also propose and test the antecedent effects of conditional and epistemic value. This approach advances the value literature through increasing our understanding of how individual value dimensions influence post-purchase behavior and of the role of epistemic and conditional value. Using a sample of 579 mobile service users, results are analyzed with multi-group structural equation modeling. The findings support use of multidimensional value and loyalty constructs to identify differences between service user groups, and argue for the use of differentiated value-based marketing strategies for entertainment and information mobile services. © 2008 Wiley Periodicals, Inc. [source]