Antoni Gelonch

Design and implementation of a wide-band real-time mobile channel emulator

A new wide-band mobile channel emulator for the CODIT project is designed and implemented. The UMTS code-division testbed (CODIT R2020) is a research project within the European RACE-II program set up by the Commission of the European Community. Our goal is to be able to simulate in the laboratory, in real time, the multipath propagation found in the mobile radio channel. As code-division multiple access (CDMA) is the access technique within the CODIT project, it was realized that the channel emulator must have simultaneously good delay resolution between propagation paths and long duration of the impulse response. These considerations led to a very flexible channel emulator specifically designed to host the new wide-band channel models developed within the CODIT project. Our emulator features three independent inputs and two outputs, up to 20 complex propagation paths, 10-MHz radio frequency (RF) bandwidth, a delay resolution of 50 ns, and a maximum duration of the channel impulse response of 80 /spl mu/s. Starting with an explanation of the global structure of the new channel emulator, we derive the optimum design of the interpolation procedures and present the main implementation issues arising from our initial architecture. Finally, we report the results of the laboratory tests of the first prototype of the channel emulator.

A Computing Resource Management Framework for Software-Defined Radios

Software-defined radio (SDR) is an emerging concept that leverages the design of software-defined and hardware- independent signal processing chains for radio communications. It introduces flexibility to wireless systems, facilitating the dynamic switch from one radio access technology to another or, in other words, the de and reallocation of computing resources from one SDR application to another. This paper introduces an SDR computing resource management framework. It accounts for several SDR system characteristics, including real-time computing requirements, limited computing resources, and heterogeneous multiprocessor platforms. The framework features the tw-mapping, a dynamic mapping algorithm that is apt for many cost functions and radio scenarios. The cost function proposal dynamically manages the available computing resources to satisfy the SDR computing constraints. Two SDR scenarios, based on representative SDR platforms and processing chains, and the corresponding simulation results demonstrate the frameworks relevance and suitability for SDRs.

Aloe: An open-source SDR execution environment with cognitive computing resource management capabilities

Future radio transceivers will offer more functionalities and system features for potentiating flexible and reconfigurable radio access networks. Since flexibility in this case comes at a price of computing resource overhead, we propose a conceptually simple though powerful framework for digital signal processing applications. The abstraction layer and operating environment (ALOE) is an open source execution environment for software- defined radios. It is essentially based on a hardware abstraction layer, a lightweight and time-driven software architecture, and a simple interface format. ALOE accounts for heterogeneous multiprocessor platforms. Its cognitive computing resource management capabilities enable flexible and dynamic management of SDR platforms and applications for distributed realtime execution of applications and dynamic reconfiguration of platforms.

Software radios: unifying the reconfiguration process over heterogeneous platforms

Future radio transceivers supporting the software radio concept will provide increased features for radio access networks. However, the reconfiguration of radio equipment requires the existence of an architecture, a common framework, which allows the flexible management of software running on radio processors. Such a framework must take into account the heterogeneity of hardware devices and platforms for radio applications. Since the flexibility has a cost in terms of added overhead, a conceptually simple but efficient structure that allows powerful mechanisms to develop and deploy software radio applications is required. This paper describes our approach, the reasons that motivated it, and some implementation issues. The proposed framework is essentially based on four items: an abstraction layer which hides any platform-dependent issue, a simple time-driven software structure, a delimited interface format for software blocks which does not actually constrain communication, and a global time-reference mechanism to guarantee real-time behaviour.

Resource Modeling for a Joint Resource Management in Cognitive Radio

Cognitive radio characterizes an ambient aware and software-defined radio system that is capable to autonomously and intelligently adjust the system parameters. It has the potential to optimize the usage of all relevant resources for service- driven wireless communications. We identify four types of resources; these are the radio, the computing, and the radio and user application resources. This paper presents their modeling, including several models for each resource type. The modeling serves as the basis for a joint resource management in a cognitive radio system that may eventually trade-off one resource (type) against the other(s). Two approaches for such a management are presented: a distributed-cooperative and a centralized- integrated. We finally discuss the applicability and utility of the proposed models, and the potentials of a joint resource management in cognitive radio in terms of user satisfaction and revenues.

EVEREST testbed: QoS management evaluation in B3G networks

This paper describes the motivation, methodology and implementation approach of the testbed that has been developed in the framework of the EVEREST project. Such testbed is used for demonstrating some of the main concepts addressed within the project, concerning both: common radio resource management strategies and end-to-end QoS architectures and mechanisms for B3G systems based on the UMTS architecture. The complexity of the interaction between B3G systems and the user applications, while dealing with the QoS concept, pushes to develop this kind of emulation platforms, where algorithms and applications can/must be tested in realistic conditions, not achievable by means of off-line simulations

A feasible approach for QoS management in coordinated heterogeneous radio access networks

This paper develops a feasible architecture for end-to-end QoS management over B3G networks where multiple heterogeneous radio access networks (RAN) can be coordinated at radio level by means of supporting common radio resource management (CRRM) functionalities. The presented approach is claimed to be innovative as long as it is inspired in the most relevant trends being developed in different fields and forums and come up with a global solution capturing such partial concepts. A key point of the architecture is the introduction of a wireless QoS broker entity that becomes the link between CRRM and E2E QoS management. In the paper, after introducing the proposed QoS framework, the signaling and procedures to support such architecture in the B3G network are addressed. Over such a basis, a connection establishment procedure is discussed to show how the problem of initial RAN selection can be managed by the proposed architecture.

Software radio implementation of a DS-CDMA indoor subsystem based on FPGA devices

Software radio will have an important role in future terminal and base station definition. Although the ideal software radio architecture is highly restricted by technology, at present it is possible to build complex systems completely customised and reconfigurable using FPGA devices. They provide the designer with the possibility of modifying the hardware functional qualities without giving up high performance or using resources poorly. To check how important is this affirmation considering future wideband systems, a representative DS-CDMA subsystem has been built over an FPGA platform that allows fast reconfiguration of internal system blocks.

Deployment and management of SDR cloud computing resources: problem definition and fundamental limits

Software-defined radio (SDR) describes radio transceivers implemented in software that executes on general-purpose hardware. SDR combined with cloud computing technology will reshape the wireless access infrastructure, enabling computing resource sharing and centralized digital-signal processing (DSP). SDR clouds have different constraints than general-purpose grids or clouds: real-time response to user session requests and real-time execution of the corresponding DSP chains. This article addresses the SDR cloud computing resource management problem. We show that the maximum traffic load that a single resource allocator (RA) can handle is limited. It is a function of the RA complexity and the call setup delay and user blocking probability constraints. We derive the RA capacity analytically and provide numerical examples. The analysis demonstrates the fundamental tradeoffs between short call setup delays (few processors) and low blocking probability (many processors). The simulation results demonstrate the feasibility of a distributed resource management and the necessity of adapting the processor assignment to RAs according to the given traffic load distribution. These results provide new insights and guidelines for designing data centers and distributed resource management methods for SDR clouds.

Computing Resource Management for SDR Platforms

Software defined radio (SDR) is an emerging technology that is based on the software implementation of the signal processing blocks found in a radio transceiver. The switch between radio access technologies may then be as easy as changing the software running on a future SDR terminal. SDR terminals refer to mobile equipment and base stations. These terminals will comprise general purpose processors, digital signal processors and/or reconfigurable logic devices. As a result, typical heterogeneous computing problems may appear in the SDR context. This article focuses on the mapping issue, discusses its relevance in software defined radio, and introduces an adequate mapping algorithm. The algorithm efficiently tackles the problem of mapping SDR function chains, i.e. signal processing blocks of a SDR transceiver, to heterogeneous processing platforms. We expose our approach, discuss its performance, present extensive simulation results and derive conclusions