Create a flexible EDGE data receiver(Part 1)

Today''s integrated solutions don''t necessarily have to result in a high level of complexity.

The introduction of new wireless standards often places tremendous pressure on the underlying technologies, especially the data receiver. This receiver contains specific intellectual property that''s a performance differentiator through the type approval and operator acceptance process and is a critical part of the solution, as it helps determine the wireless terminal''s complexity and power.

In the case of the EDGE (Enhanced Data Rates for GSM Evolution) standard, the key factors are: complex modulation format, different modulation/coding scenarios, and possibility of link adaptation. Each factor further stress the importance of data receiver design.

EDGE receiver development follows the phases that have been observed in GSM history. In the first phase, an emphasis was placed on the low complexity algorithms to provide satisfactory performance. The second phase was associated with volume production where mature algorithms were mapped onto cost-effective solutions. Finally, proliferation of integrated solutions with large computational capability on one side, and increased system requirements on the other side to various performance enhancing approaches.

One can argue that all three phases are happening simultaneously in EDGE development. Performance differences between various equalization schemes are bigger than observed in GSM and advanced equalization and performance enhancing techniques are necessary from the beginning. This in turn puts immediate pressure on the complexity of the solution to meet high expectations in the product space (size, power) set up by GSM/GPRS advanced terminals.

The EDGE system''s new features that directly impact data receiver design are a new modulation scheme (8PSK) and a new link adaptation/incremental redundancy protocol. The EDGE standard extends the adaptive coding principle introduced in GPRS by introducing nine modulation-coding schemes, MCS1 to MCS9. The first four schemes, MCS1 to MCS4, use GMSK modulation, while the remaining five schemes, MCS5 to MCS9, use 8PSK modulation.