Professor Umran S. Inan

Winter 1998-99

Date: Wednesday, January 13, 1999
Time: 4:15-5:30 PM; Refreshments at 4:00 PM
Location: ** Building 260, Rm. 113 **
**(please note new location)**

Some Key Aspects of Solar-Terrestrial Coupling

Prof. Andrea Goldsmith
Electrical Engineering, Stanford University


The spectral efficiency of flat-fading channels can be significantly increased when the transmitter adapts its power and rate to the channel variation. We therefore propose an adaptive MQAM modulation technique which optimally adapts its power and rate to maximize spectral efficiency. The resulting efficiency is calculated and compared to the theoretical maximum. Additional coding gain can be obtained by superimposing a trellis or turbo code on top of the adaptive modulation. Our modulation is sensitive to estimation error and delay, and we quantify the degradation in performance resulting from these effects. We also show how adaptive modulation can be used in narrowband and CDMA multimedia systems to meet different data rate and BER requirements. We conclude the talk by applying adaptive modulation to a TDMA cellular system. We determine the resulting area spectral efficiency (bps/Hz/unit area) for various power adaptation algorithms, propagation conditions, reuse factors, and cell sizes.