Overall Objectives
Scientific Foundations
Application Domains
New Results
Contracts and Grants with Industry
Other Grants and Activities

Section: New Results

Reconfigurable Radio

Software architecture:

[34] presents a software architecture based on the virtual machine concept for SDR implementation. A high level abstraction language for the specification of PHY layer configurations has been proposed. In order to validate our concept and prove its practicality we have implemented IEEE802.11a PHY transmit and receive functionalities on a software demonstrator based on the Lua VM. This experiment has shown that both programming and execution model.

Architecture multi-standards:

Multi-mode is a common feature in current generation terminals, enabling the user to stay connected at any time. By selecting an appropriate standard, multi-mode can reduce terminal power consumption. Software Defined Radio is an enabler towards multi-mode for the next generation of terminals. In such a radio, communication modes are implemented by a general processor through digital functions, instead of dedicated chips. Providing access to users in bad conditions through relays, is another solution to reduce power consumption. This work is supported by the thesis of Cédric Levy-Bencheton.

In [45] , [26] , we look at multi-mode relaying, where a mobile terminal, connected to an UMTS base station, acts as an 802.11g-relay for those users. In this paper, we evaluate the algorithmic complexity of 802.11g and UMTS to estimate the power consumption of a Software Defined Radio. We propose a multi-mode relay scheme using such terminals, with the purpose of minimizing the global power consumption. Finally, we enounce different rules to maximize the local and global power gain by implementing multi-mode relays.

Multi antenna architecture:

The design of radio front-end has been extensively considered in [42] , [18] , [16] , [17] , [21] , [43] , [21] , [19] , [20] . Two problems have been considered: multistandard front-end and diversity receiver. For instance, [16] , [17] aim to reduce the complexity of the analog front-end for a multistandard simultaneous reception receivers. To this end, we propose an architecture using the double orthogonal translation technique in order to multiplex two signals received on different frequency bands. A study case concerning the simultaneous reception of 802.11g and UMTS signals is developed in this paper. Theoretical and simulation results show that this type of multiplexing does not significantly influence the evolution signal to noise ratio of the signals.

For the problem of antenna diversity, an innovative architecture is introduced based on code multiplexing in [21] , [43] , [21] , [19] , [20] . This architecture uses the direct sequence spread spectrum technique in order to multiplex the different antennas contributions through a single IQ demodulator. Simulation and measurement results show that, in a Gaussian case, the bit error rate does not increase so much with the multiplexing. The complexity evaluation shows that the proposed architecture significantly reduces the power consumption of the front-end. IQ imbalance study in [19] , [20] shows that the new architecture has the same sensitivity to IQ mismatches than the classical stack-up architecture and he bit error rate does not increase significantly with the multiplexing and this increase is compensated for a high IQ imbalance. A major result of this contributions is the proposition of candidate architecture for LTE Advanced receiver [48] .


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