Matched Filter Based Receiver Technology

Matched filter based Direct Sequence Spread Spectrum (DSSS) systems offer performance that is superior to that of alternative system implementations. The many benefits associated with such systems stem from the fundamental agility of matched filter structures in acquiring and tracking DSSS signals and their multipath components.

In spite of these advantageous operational characteristics, the power consumption and implementation complexity associated with matched filter based DSSS systems have kept such systems from being widely available in consumer products. GBT has addressed the problem of power consumption and implementation complexity associated with matched filter based DSSS systems. Applying GBT innovations, complex packet-data based systems now benefit from the advantages offered by matched filter based system designs and implementations.

Acquisition is the fundamental process in DSSS systems. The ability to perform quick and accurate signal acquisition is essential for all high performance DSSS systems. The high processing rates associated with matched filter based receiver structures enable such systems to concurrently examine all signals arriving within a prescribed multipath delay profile, identify all present signals and select any number of them for further processing with minimal delay. This processing applies to the acquisition as well as to the multipath identification and tracking processes.

System level benefits made possible by an efficient signal acquisition structure extend to the new WCDMA (3G) systems as well. Extensive standby times and superior performance in mobile, or otherwise difficult environments, directly relate to the efficiency of the signal acquisition system. It can be shown that systems that use matched filter based architectures are always superior to systems that use correlator bank architectures.

In summary, the ability of matched filter-based systems to concurrently, rapidly and accurately process DSSS signals within a prescribed multipath delay profile is the fundamental reason that makes matched filters so desirable. Realistic matched filter based architectures became possible due to GBT innovations that greatly reduce complexity and power consumption of such architectures. All GBT ASICs are low cost, power efficient, matched filter based DSSS modems for commercial applications.

Signal Acquisition
Wide-band system’s incoming signal has a higher data rate and is embedded in a much wider bandwidth.

Acquisition processes are used for:
•	Cell identification (cold start)
•	Cell list update (continual)
•	Multipath identification
Good quality of acquisition generates:
•	Quick ‘dial-up tone’ or network access
•	Best communication performance (RAKE)
•	Long standby time
Standby time affected by:
•	RF System (transmitter and receiver sections)
•	IMT2000 Baseband System

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IMT2000 Acquisition System

Acquisition System Performance