Vijay K. Varma

Integrated alerting and system broadcast channel for a wireless access system

A protocol is described which allows a wireless access system to dynamically multiplex the alerting, system information, and priority access request subchannels on its system-wide broadcast channel. These subchannels each have different requirements with respect to the message length and position within the framing structure; the described protocol meets each of their requirements. The protocol efficiently accommodates a wide range of alerting traffic levels and provides for efficient downloading of system information to subscriber units by using excess capacity when alerting traffic is low. It provides error detection capabilities above that provided by the radio channel alone and is easily extendible to accommodate other services such as paging and low bandwidth broadcast messaging. The flexibility provided by this protocol could permit a broad range of network architectures for wireless access.

Partial response continuous phase modulation and DPCM coding for speech transmission in cellular mobile radio systems

The performance of a speech transmission scheme with application to cellular digital mobile radio systems is considered. The source coder is embedded differential pulse code modulation (DPCM) and the modulation schemes belong to the class of partial response continuous phase modulation (CPM). Both quantizing noise and transmission errors contribute to the overall mean square error. The performance measure is the audio signal-to-noise ratio (SNR). It is seen that in a fading environment space diversity is very effective in bringing down the threshold of channel SNR to maintain the required audio SNR. The number of channels the system can support is evaluated under various conditions.

Guest Editorial: Special Issue on Advances on Wireless LANs and PANs

The evolution and successful deployment of Wireless Local Area Networks (WLANs) and Wireless Personal Area Networks (WPANs) worldwide has paved the way to more intense standardization and R&D activities, that target even more sophisticated and advanced WLAN/ WPAN systems. Standardization activities within the IEEE 802.11 working group are well underway for evolving the dominant WLAN standard in several aspects, including security, mobility and quality of service (QoS). In addition, alternative physical and MAC layer proposals are being considered for improving bit rates to ranges in excess of 100 Mbps. Similar activities are taking placing within the ETSI BRAN project to further evolve the HIPERLAN/2 standard. At the same time, the core representative of WPANs, i.e. Bluetooth, is being further evolved by IEEE 802.15 TG1. Other task groups within IEEE 802.15 develop specifications for high-and low-rate WPANs, known as IEEE 802.15.3 and IEEE 802.15.4 respectively. Moreover, interworking mechanisms are being investigated for combining WLAN/WPANs and second-/third-generation cellular networks into hybrid data networks, capable of very high bit rates in strategic locations (hotspots). 3GPP is one notable standardization body that has been standardizing such interworking mechanisms for a long time. Last but not least, it is important to note the numerous research projects worldwide that address a vast collection of issues related to WLANs and WPANs, ranging from the seamless mobility across UTRAN and WLAN to heterogeneous multihop wireless networks consisting of combinations of WPAN and WLAN technologies. All these activities combined with market forecasts, which report that WLANs and WPANs will encounter a tremendous growth in the next years, demonstrate that WLAN and WPAN technologies will play a significant role in the future and will severely impact our business and personal life styles. However, several issues still need to be efficiently addressed, including power consumption, physical and MAC layer architectures, radio resource management, inter-working, QoS, security, coexistence with other unlicensed technologies, self configuration, etc. The special issue we put together contains eleven articles, which address a vast range of aspects related to wireless LANs and PANs. In particular, physical layer aspects are discussed, such as techniques for higher throughput, ultra-wideband channel models and WLAN/WPAN coexistence. MAC layer aspects include protocol proposals for improved performance and analysis of QoS issues. Higher layer aspects include suggestions for enhanced authentication and security, discussions about pico-cellular deployments, network resource management, etc. In more detail, the papers presented in this issue are the following. The first …

Architectures and protocols for mobility management in all-IP mobile networks [guest editorial]

The seven Special Topic articles focus on the architectures and protocols for mobility management in all-IP mobile networks. The articles are summarized here.

Interference, sensitivity and capacity analysis for measurement-based wireless access spectrum sharing

In this paper, interference caused by multiple uncoordinated low-power wireless access system transmitters to fixed point-to-point microwave receivers is analyzed. The analysis shows that the density of wireless access system users that can share spectrum with point-to-point microwave systems depends critically on the propagation relation, the threshold of detecting energy from point-to-point transmitters, and the allowable interference into point-to-point receivers. We also show that, for reasonable assumptions of point-to-point link, wireless access system, and propagation parameters, a wireless access system employing measurement-based interference avoidance must detect energy of point-to-point transmissions far below the thermal noise floor of the wireless access system receivers. Meeting this requirement could increase the complexity of wireless access systems. This work is targeted towards understanding the implications for local exchange networks of wireless system alternatives that could provide access to those networks. >

Architecture and mobility management issues for wireless next generation networks

In this paper, we discuss three possible steps for evolving existing wireless network towards a fully integrated wireless network based on IP (Internet Protocol) technologies. In these evolution steps, the transport and mobility management of both voice and data traffic is gradually transformed from circuit-based into packet-based mechanisms.

A secure virtual point of service for purchasing digital media content over 3G wireless networks

We propose the notion of a Secure Virtual Point of Service (SVPOS) as a network-centric transaction server that facilitates the enhancement of 3G cell phones with a ‘mobile wallet’ capability allowing 3G subscribers to use their cell phones (or, in fact, other preferred mobile gadgets) for their daily transactions and payments. This paper shows how to design an SVPOS and an associated operator/subscriber/merchant protocol for purchasing digital media content over 3G networks. The resulting protocol guarantees a number of desirable privacy and security properties, such as privacy/anonymity of 3G subscribers (i.e. no identities, credit information or credit card numbers are revealed by subscriber to merchants), and protection of 3G operator, merchant, subscriber against various types of malicious behaviour, including transaction repudiation. The proposed SVPOS is ‘built’ on top of the Hypertext Transfer Protocol (HTTP), utilizes the 3rd Generation Partnership Project (3GPP) Generic Authentication Architecture (GAA) for subscriber and merchant authentication, and has an implicit key distribution mechanism that easily provides necessary encryption keys for the novel non-repudiation mechanism of SVPOS. It also sends the necessary records of the transactions to the accounting entity of the network for charging and billing through standard protocols (e.g. Parlay-X). Copyright

Architecture alternatives for PCS-to-Internet protocol interworking

As the growth rate of the Internet subscription increases, the demand for providing wireless access for Internet applications becomes apparent. While packet data networks like CDPD, RAM, and Metricom provide Internet services, their channel capacity is generally insufficient for Internet applications such as Web browsing. Asymmetric high-speed wireless access techniques that support wide-area high-speed Internet applications have been studied and investigated extensively in the industry. However, the network architecture to support interworking of the high-speed wireless access network with the Internet has not been widely discussed. This paper addresses architecture alternatives for interworking of high-speed wireless access network, with Internet backbone for providing a seamless wide-area wireless Internet access service.