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3π/8 offset 8PSK modulation in EDGE GSM
Sharma, Amit Ramkripal
harris, fred j.Kumar, SunilEckberg, CArl
xii, 45 p. : ill.
This thesis is about the EDGE GSM technology. The study starts with the understanding of what kind of modulation techniques are used in this technology. EDGE GSM is the next step in the evolution of GSM and IS-136. The aim of the new technology is to increase data transmission rates and spectrum efficiency and to facilitate new applications and increased capacity for mobile use. EDGE GSM is a method to increase the data rates on the radio link for GSM which uses 8 phase shift keying (8PSK) for modulation and coding schemes. EDGE GSM produces a 3-bit word for every change in carrier phase. This effectively triples the gross data rate offered by GSM. In 8-PSK modulation, the trajectory of the modulating data (I and Q) goes through zero origin. Where the trajectory crosses the origin, non linearity at low power regions will distort the signal and, hence, produce spectral re-growth. To overcome this situation, it would be useful if the origin somehow could be avoided for the modulating data. The introduction of 3π/8 offset to the 8-PSK with a higher spectral efficiency requires new and more complex algorithms for the equalization part as well as for the coding and decoding part. The transmitted signal once it has been filtered is difficult to interpret. Hence, Error vector magnitude is used to assess the received signal. In addition to 8-PSK, EDGE also adds the important concept of Link Quality Control
Includes bibliographical references (p. 45)
Electrical and Computer Engineering
Master of Science (M.S.) San Diego State University, 2012
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