Description
Date depot: 1 janvier 1900
Titre: System considerations for Multi-mode Base Station Transmitters
Directeur de thèse:
Patrick LOUMEAU (LTCI (EDMH))
Domaine scientifique: Sciences et technologies de l'information et de la communication
Thématique CNRS : Non defini
Resumé:
Contemporary telecommunication Base Stations for GSM/EDGE, WCDMA/HSPA and LTE are increasingly complex and energy intensive, necessitating efforts to alleviate the network bottlenecks in performance and power consumption. Increased subscriber activity, introduction of new standards with challenging performance requirements and limited resources, exacerbate the problem. As a conceivable solution, a convergent multistandard transmitter, together with advanced antenna, signal processing and PA technologies favors lesser power consumption besides having a smaller footprint. Furthermore, this also facilitates easy deployment and efficient resource management.
Modern base station transmitters are often multi-standard, in that they can support different air-interface standards. However this is achieved not concurrently or simultaneously, but through reconfiguration, either during installation of the cell-site or during
its operation. In order to identify the feasibility of multi-mode transmission, this work attempts to analyze a first-order approximation based system design of such an RF chain, exploiting a unique opportunity for innovation. The concurrent operation of multiple standards on shared hardware results in several stringent requirements on the performance of the multi-mode RF-transmitter. The
analysis of a few parameters or metrics in particular (e.g. Error-Vector-Magnitude and Adjacent/Alternate Channel Leakage Ratio), as set by the standards, has allowed me to translate system level requirements to block level performance specifications. By analyzing
the block level contributions to all the signal-distortions in the modulation quality metric (EVM) and spectral leakage (ACLR), it is possible to derive individual block level performance requirements (e.g. phase noise, IP3, noise factor etc.). In this analysis, I
also develop, in the second part of the work, the mechanism for performance budgeting among the various analog blocks in the chain based on first-order contributions (nonlinear distortions, phase noise, IQ imbalances, additive noise etc.) from each block in a
typical transmission chain. At the same time however, there exist also system level challenges in the multi-standard Base Station operation (e.g. crest factor reduction, carrier-to-carrier interference mitigation, per-carrier power control etc.) which relate to additional system performance requirements that are also highlighted in this work. With the evolution of 3GPP standards towards multi-mode operation being in its nascent stages, I attempt to analyze and redefine the architecture of the traditional macrocell
Base Station transmitter envisioning such a multi-standard solution. Detailed discussions and deliberations from system analyzes and block level implementation of a variable gain interface between the DAC (reconstruction-filter output) and the AQM for such an RF chain will be included in the final work.
Doctorant.e: Kowlgi Srinivasan Sandeep