Eiman Bushra Mohyeldin

Investigation of radio resource scheduling in WLANs coupled with 3G cellular network

In this article, based on the overview of network coupling structure between radio access technologies, the concept of joint radio resource management built onto the reference structure is introduced. In order to optimize usage of radio resource and jointly designed from the user perspective, a joint scheduling mechanism allowing traffic to be split over a tightly coupled radio network supported by an adaptive radio multihoming approach is deliberately discussed. With respect to the time-division access scheme in HIPERLAN/2, which is selected as one example of WLAN, algorithms and performance of traffic scheduling in such a radio access technology are given. The required synchronization scheme supporting traffic splitting is also introduced.

A generic framework for context aware and adaptation behaviour of reconfigurable systems

It is clear that the reconfiguration of mobile SDR terminals requires complex interactions between the mobile terminal and the network or application server entities. To enable mobile devices to utilize different radio access technologies and communication protocols depending on the requested application QoS and to enable development of context aware application that can adapt their level of functionality to dynamic radio resource restrictions like available bandwidth, delay and link interruptions, a generic software framework for adaptation and reconfiguration is necessary. In this paper we describe a generic technical and methodical framework for designing context awareness and adaptation behaviour that is based on formal methods, thus allowing for a sophisticated engineering approach in designing and implementing complex context aware adaptive systems. This framework supports the development of customized middleware, reconfigurable protocol stacks and adaptive application services for the three main phases of reconfiguration: profile and context management, adaptation decisions, and technical deployment

Network support modeling, architecture, and security considerations for composite reconfigurable environments

Emerging radio access technologies such as wireless personal and metropolitan area networks and digital broadcasting are a new era for wireless communications. These standards aim at complementing existing cellular/Wi-Fi networks in order to offer a wide range of available access modes to mobile terminals. Multiradio wireless systems referred to as composite radio access networks, bear diverse capabilities, with the optimal radio being invoked to perform a specific set of functions. Composite reconfigurable radio networks support the collaboration of a wide range of heterogeneous radio access technologies under a single or multiple administrative boundaries, adding further intelligence to the way devices attach to and switch between networks spatially and temporally. The EU End-to-End Reconfigurability (E2R) research project envisages composite reconfigurable radio networks coupled with legacy as well as evolved core network architectures, yielding simpler and flexible configurations for reduced latencies, autonomic operation, and adaptive functionality. This article presents a cohesive model for controlling and managing such networks, elaborates on the constituent functional entities, and maps this model to two-tier network support architecture. Finally, key security issues for software download over reconfigurable radios and systems are identified and solutions for software certification and authorization as well as for the authentication of roaming terminals are proposed.

Dynamic classmarks for SDR equipment

The paper describes a dynamic classmark scheme based on a finite number of stages during a radio connection procedure for reconfigurable terminals in future multiple radio access technology environments. Based on the user profile, terminal profile and service profile that the user applies, features are clustered into different sets called classmarks. The classmarks are designed in a stage-based manner in order to realize the method of dynamically creating and triggering them. During the reconfiguration, radio link establishment and communication processes, the number of stages is adaptive to the access frequency and priorities of the necessary features required by the network. Thanks to this approach, the signaling burden is highly reduced in the radio network. Therefore, the efficiency of radio resource management is improved.

Optimal HSDPA multi-cell power allocation in a moving hotspot scenario

In the context of dynamic network management, the HSDPA power allocation in each cell is considered in this paper as a mean of assigning resources through a wireless network in an autonomic way. Under the umbrella of end-to-end reconfigurability as stated in the E2R EU funded project, dynamic management is enabled by allowing on the fly reconfiguration of network parameters, leading to an optimized use of resources and more flexibility in allocating resources of heterogeneous networks based on demand. The test scenario consists of a moving hotspot, where users are served by a high speed shared data channels. All available spreading codes are given to one user at a time, and a queuing model based on M/G/1-PS is used to evaluate the throughput and the response time both in the hotspot cell and the neighboring cells. A basic algorithm consisting of a total cell power allocation proportional to the number of user waiting to be served is investigated, of which gains in terms of hotspot throughput were proven to be higher than the losses incurring in neighboring and less populated cells. A typical scenario where the hotspot occurs is for example when users move to an area known to be crowded at a certain point of time during the day, but then move again to a neighboring area due to another interest there. The hotspot could also occur in an unexpected way (traffic jam, special events), and resources have to be adapted intelligently and autonomously. The efficiency of such an algorithm is investigated in terms of different parameters. Moreover, in the course of looking for a boundary for the performance of such an algorithm, we propose a simulated annealing based approach to find the optimal power distribution to evaluate the proximity of simpler and faster algorithms to such an optimum

Network controlled adaptive antenna tilting in multi-band UMTS FDD

This work proposes an adaptive antenna tilting approach in an overlay UMTS FDD network. The purpose is to introduce and investigate an antenna element, which can be remotely controlled by the radio network, in order to adequately cater for the spatial and temporal dynamic traffic distributions. The tilting angle is computed by a two level control mechanism: the higher level is controlled by the network manager and consists of a look-up table with the possible ranges (intervals or discrete steps for angles) of the antenna angle adjustments. The element manager, e.g. RNC controlling and recording the track of the dynamic antenna changes, controls the lower level. To enhance the system reliability, we associate the less dynamic traffic with the primary fixed tilt antenna, whereas the more varying traffic is controlled by a second more dynamically tilted antenna element. Through system level simulations, we show that significant gains in term of system capacity can be obtained. In addition, solutions involving the network management subsystem in UMTS FDD are also given, where the element management platform interacts with the performance measurement units. Intelligent inter-frequency handovers are deliberately discussed.

Efficient radio resource management scheme for multimedia services in broadband mobile networks

The paper defines a radio resource management concept for multimedia services in future broadband mobile radio networks. Based on the HIPERLAN/2 system, we design an adaptive radio resource scheduler which autonomously adapts to current traffic types and volume. We assume IP traffic models for voice, HTTP and video users and optimize the scheduling functions in the access point (base station) of the broadband mobile network in order to maintain QoS for the services. The interworking among admission control, load control and the adaptive scheduler is shown. The principles discussed here are not restricted to H/2 but can be exploited for any radio access technique (RAT) using adaptive schedulers, e.g. dynamic scheduling for reconfigurable terminals.