Soodesh Buljore

Architecture and enablers for optimized radio resource usage in heterogeneous wireless access networks: The IEEE 1900.4 Working Group

Over the past decade or so, the wireless industry has undergone many significant changes. Radio systems have moved toward forming heterogeneous wireless networks: collaborations of multiple radio access networks, which in some cases operate different radio access technologies, such as second- and third-generation cellular RATs, IEEE 802.x wireless standards, and so on. On the other hand, multimode reconfigurable user devices with the ability to choose among various supported RATs have become a reality, and devices and networks with dynamic spectrum access capabilities, allowing real-time sharing of spectrum resource usage among different systems, are expected to be a part of the future radio eco-space. As a result of these changes, there is a need to develop a standard that addresses the requirements and leverages the opportunities posed by such a versatile radio environment. To this end, IEEE 1900.4 aims to standardize the overall system architecture and information exchange between the network and mobile devices, which will allow these elements to optimally choose from available radio resources. In other words, the standard facilitates the distributed dynamic optimization of the usage of spectrum offered by the heterogeneous wireless network, relying on a collaborative information exchange between networks and mobile devices, thereby acting as a common means to improve overall composite capacity and quality of service for the served networks. This article provides a snapshot of IEEE P1900.4 in its current form, covering the scope and purpose of the standard, reference use cases for which the standard is applicable, its system and functional architectures, and finally, the information model for its main interfaces.

Terminal-centric view of software. reconfigurable system architecture and enabling components and technologies

Reconfigurable radio in Europe is rapidly gaining momentum and becoming a key enabler for realizing the vision of being optimally connected anywhere, anytime. At the center of this exciting technology is the reconfigurable terminal that will move across different radio access networks, adapting at every instant to an optimum mode of operation. This will require coordinated reconfiguration management support from both the terminal and the network, but the terminal will inherit a significant part of this intelligence. This article focuses on a novel reconfigurable terminal architecture that advances the state of the art and encompasses the overall protocol stack from the physical to application layer in IP-based radio access networks. The proposed architecture is composed of a terminal reconfiguration management part and enabling middleware technologies like the complementary Distributed Processing Environment and agent platforms, flexible protocol stacks that can flexibly be interchanged to support different wireless technologies and associated mechanisms, and finally, object-oriented reconfigurable RF and baseband components. The work presented in this article is conducted in the context of the IST projects SCOUT (www.ist-scout.org) and TRUST (www4.in.tum.de/-scout/trust webpage/spl I.bar/src/ trust frameset.html) of the European 5th Framework Program.

IEEE P1900.B: Coexistence Support for Reconfigurable, Heterogeneous Air Interfaces

This contribution presents and discusses the system concept approach which has been proposed by the European Integrated Project IST-E2R II in the IEEE P1900.B Standardization Study Group (SG); it currently is under further elaboration in the framework of the follow-up IEEE P1900.4 Working Group (WG) whose Project Authorization Request (PAR) was accepted in December 2006. This effort targets reconfigurable (typically software defined radio (SDR) based) networks and terminals in a heterogeneous wireless environment, with multi-homing capable terminals enabling the users to operate multiple wireless links simultaneously. In order to ensure backwards compatibility to legacy standards, the approach is to introduce three new building blocks into the (existing and/or evolving) heterogeneous landscape: i) A network reconfiguration management module, ii) a radio enabler and iii) a terminal reconfiguration management module. Within this paper, the key functionalities of these building blocks are detailed and discussed; it is furthermore outlined how the introduction of distributed decision-making concepts improves the efficiency of the heterogeneous system in terms of i) signaling overhead, ii) reactivity of user mobile terminals (MTs) and iii) numerical resource selection optimization complexity on the network side.

Equipment management issues in B3G, end-to-end reconfigurable systems

The evolution of wireless communications in recent years has resulted in a clear trend toward Beyond Third Generation (B3G) systems, which support the integration and co-existence of multiple, diverse radio access technologies (RATs) in a common composite radio environment. The reconfigurability concept has been developed for the facilitation of B3G Systems. Reconfigurability supports the B3G concept by providing technologies that enable equipment (terminals and network elements) to dynamically select the most appropriate reconfiguration action. In this direction this article outlines some key issues for embedding reconfigurability functionality in equipment. A generic management system for reconfigurable equipment (MSRE) in B3G environments is presented and the functionality of its main components is described in detail.

A peak-to-average power reduction method for third generation CDMA reverse links

Proposals for third generation cellular standards based on code division multiple access (CDMA) methods are being developed in several standards bodies around the world. The reverse link (mobile-to-base station) in these proposals is similar in structure and function. A method is described that reduces the peak-to-average power of the mobile station transmission. By reducing the peak-to-average power ratio, spectral regrowth created by the mobile station power amplifier is reduced. This method is known as hybrid PSK (HPSK). HPSK is utilized in the generation of the complex scrambling sequence of the reverse link. Currently, HPSK has been adopted for the reverse link of third generation CDMA proposals by the TIA for the USA, ETSI for Europe, ARIB for Japan, and TTA for Korea.

IEEE P1900.4 System Overview on Architecture and Enablers for Optimised Radio and Spectrum Resource Usage

The field of application of the IEEE P1900.4 standard is radio systems forming a composite radio access network, i.e. with multi-radio access networks (RAN) using different radio access technologies (RAT). The end-user terminals are multimode terminals, supporting several RATs, with multi-radio link capabilities and having cognitive radio capabilities, such as operating flexibly on different frequency bands. The composite radio access network is assumed to be operated by either a single or several operators. Within this field of application, the standard provides common means to improve overall composite capacity and quality of service through distributed optimization of the usage of spectrum and radio resources offered by the composite radio access network. Basically, the optimization relies on a collaborative information exchange between the composite network and terminals. For this purpose, two entities are identified to facilitate this collaboration: network reconfiguration manager (NRM) and terminal reconfiguration manager (TRM), whilst the communication between NRM and TRM is ensured via a logical communication channel, the radio enabler (RE). Accordingly, this paper provides an overview of the IEEE P1900.4 scope and purpose, the reference usage cases wherein the standard would be applicable, including system requirements, architecture, and its reference model with main interfaces linked to the information model that is currently being developed.

IEEE P1900.4 Standard: Reconfiguration of multi-radio systems

The field of application of the IEEE P1900.4 standard is radio systems forming a composite wireless network, i.e., comprising multiple Radio Access Networks (RANs), which may be using different Radio Access Technologies (RATs). This composite wireless network is assumed to be operated by either a single or several operators. End-user terminals in P1900.4 are generally assumed to be multimode/multihoming, supporting several RATs and with multi-radio link capabilities, also possessing some cognitive radio capability such as flexible operation in different frequency bands. There are, however, conceivable scenarios where the P1900.4 standard would still be applicable even if terminals possessed limited such capabilities. At the core of the IEEE P1900.4 standard, Reconfiguration Management Entities (RMEs) are defined, located on terminal and network sides. The network side RME manages the terminal indirectly, but by providing/collecting context information and providing Radio Recourse usage policies to terminals. The terminal side RME makes final decisions regarding selection of the most appropriate RAT/RAN, band, etc., thereby also triggering the corresponding radio link reconfigurations in the terminal. Of course, all such decisions made by the terminal RME must be within the remit of policies conveyed by the network RME. This paper introduces the activities and work under progress within the IEEE P1900.4 working group.

Training-based channel estimation and de-noising for the UMTS TDD mode

We provide a theoretical framework of de-noising for UMTS TDD-like mobile radio communication systems. Based on the Bayesian approach, we show how to de-noise channel estimates provided by the training-based estimation procedure. The proposed schemes allow not only for eliminating major drawbacks of hard thresholding but also for a low complexity implementation.

Reconfigurable Wireless Communication Systems applying Distributed Decision-Making in a Heterogeneous Radio Environment

This contribution presents the system concept approach introduced by the IEEE 1900.4 Working Group (WG) and discusses inherent advantages and issues. This effort targets reconfigurable (Software Defined Radio (SDR) based) networks and terminals in a heterogeneous wireless environment, with multi-homing capable terminals which enables them to operate several wireless links simultaneously. In order to ensure backwards compatibility to legacy standards, this approach introduces three new building blocks into the (existing and/or evolving) heterogeneous landscape: i) A Network Reconfiguration Management module, ii) a Radio Enabler and iii) a Terminal Reconfiguration Management module. Within this paper, the key functionalities of these building blocks are presented and discussed; it is furthermore shown how the introduction of distributed decision-making concepts improves the efficiency of the heterogeneous system in terms of i) signaling overhead, ii) reactivity of user mobile terminals (MTs) and iii) numerical resource selection optimization complexity on the network side.

Closed loop transmit diversity enhancements for UMTS narrowband and wideband TD-CDMA

The aim of this work is to evaluate the performance gains obtained by using multiple transmit antennas at the Node B in the context of the low chip rate TDD option (1.28 Mcps TDD option) specified in 3GPP RAN WG1. Moreover, the existing high chip rate system (3.84 Mcps TDD option) is also considered as reference. The impact of using multiple transmit antennas at the Node B on different types of receivers, namely joint detection schemes and conventional matched filter, in several propagation environments, for a voice-like service (without channel coding) is characterized. Through simulation results, it is shown that, depending on the number of transmit antennas, it may be possible not to implement a multiuser detection scheme at the mobile station side in TDD mode based systems.