Create a flexible EDGE data receiver(Part 3)

EDGE in software
Enabling a fully-software EDGE data receiver implementation has many advantages. Design can be iterated without effecting the terminal''s hardware design while optimizing for performance in the FTA and IOT process, including performance and complexity tradeoffs. This cost-effective and power-efficient solution meets the stringent wireless handset requirements while being a future-proof platform. It allows for additional performance-enhancing techniques ranging from proprietary algorithms for enhancing EDGE to future Single Antenna Interference Cancellation (SAIC) solutions, or updates related to potential changes in the standard or field test results and adjustments.

Analog Devices'' Blackfin instruction set enables this all-software solution. For example, many vector instructions can be used that can achieve two atomic instructions in one cycle. That''s the case for the VIT_MAX instruction, which is effective not only for Viterbi decoding, but also in the DDFSE equalizer for the path metric selection. The instruction selects the maximum value of each of either one or two number pairs. It also shifts the accumulator contents and inserts two bits which represent the result of both maximum comparisons. Some of these vector instructions can be used in pairs as long as the two instructions have the same two data registers as inputs. That makes it possible to achieve four atomic instructions in one cycle. This is used in the EDGE channel decoder for the path metrics computation resulting in fewer cycles for the algorithm.

References

1. E. Yakhnich, “Channel estimation for EGPRS modems,” Vehicular Technology Conference, 2001. VTC 2001 Spring. IEEE VTS 53rd, Page(s): 419 -422 vol.1.
2. B. Lindoff, “Using a direct conversion receiver in EDGE terminals-a new DC offset compensation algorithm,” Personal, Indoor and Mobile Radio Communications, 2000. PIMRC 2000. The 11th IEEE International Symposium on , Volume: 2 , 2000, Page(s): 959 -963 vol.2.
3. W.H. Gerstacker, R. Schober, “Equalization concepts for EDGE,” Wireless Communications, IEEE Transactions on, Volume: 1, Jan. 2002, Page(s): 190 -199.

About the authors
Marko Kocic is a system design engineer with Analog Devices. He has a Ph.D. from Northeastern University, and a M.Sc. degree from University College in London. Kocic can be reached at marko.kocic@analog.com.

Lidwine Martinot is also a system design engineer with Analog Devices. She graduated from Telecom Paris (with an engineering diploma) and the University of Bristol (MSc in signal processing and communications systems). She can be reached at lidwine.martinot@analog.com.

Zoran Zvonar is manages the systems development group at Analog Devices. He received Dipl. Ing. and an MS degree from the University of Belgrade, Yugoslavia, and a Ph.D. from Northeastern University. Zvonar can be reached at zoran.zvonar@analog.com.