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• radio base station configuration;• cell control;• the distribution of system information;• radio link configuration for dedicated andcommon channels;• lub data-stream handling; and• node synchronization and distribution.The baseband functions in the radio base stationthus provide a platform for radio networkfunctions, configuration functions,and O&M functions. Accordingly, the basebandconstitutes a platform of resources forhandling common and dedicated channelsfor higher layers.Figure 3 gives an overview of standardchannel mapping between logical channels,transport channels and physical channels.''' 5The upper part pertains to the downlinkchannels and the lower part (shown in darkblue) pertains to the uplink channels. TheThird-generation Partnership Project''(3GPP) has defined the• synchronization procedures for cells, commonchannels and dedicated channels;• random-access procedures; and• inner- and outer-loop power control procedures.To improve the performance of the radiolink connection, the 3GPP has recommendedpossible enhancements, such asopen-loop and closed-loop transmit diversity.After the baseband boards have been configuredproperly with respect to the interfacesto other subsystems, they can be putinto traffic operation. If the traffic load onthe baseband is light, all or part of the boardcan be put into power save mode to reducepower consumption. By contrast, supervisionand protection mechanisms reduce therisk of dropped calls when the traffic loadon the baseband boards is too heavy.Figure 2Baseband in RBS and interfaces.Figure 3Channel-mapping model. Area marked in red is for HSDPA.Baseband design aspectsEricsson's baseband has been designed tocomply with 3GPP standards for WCDMA.In addition, the baseband architecture hasbeen designed to meet requirements for operatingradio base stations. These includeconfiguration flexibility, effective use of resources,easy roll-out, compatibility andfuture-proof hardware. By introducing thevery latest in digital signal processor (DSP),field-programmable gate array (FPGA)and application-specific integrated circuit(ASIC) technologies, Ericsson has significantlyincreased the capacity for ttaffic andcontrol signaling, measured in terms ofchannel elements for the dedicated physicalEricsson Review No. 1, 2003 33