A question I often receive is; ”which was your first invention?”. Since it is the first, I have quite clear memories of it (compared to, say number filed application no 346 ?), and below I will say some word about the first one.
US 6101224 Method and apparatus for generating a linearly modulated signal using polar modulation
I started at the Research department at Ericsson Mobile Communication February 1998, as a fresh PhD graduate. At that time, only GSM was out there and data communication was made over GPRS with a maximum data rate of 9.6 kb/s. In order to increase the data rates for 2G, EDGE, enabling higher data rates in GPRS was being standardized and a new transmission method (8-PSK) was introduced in order to increase the data rate (up to over 100 kb/s).
Such new transmission method (8-PSK) has bad transmitter efficiency (high power consumption, which is a disadvantage for battery driven handheld mobile phones) compared to the modulation used in GPRS (GMSK), and encouraged by my first Manager and one of my colleagues, we developed a power efficient transmission method where one could re-use parts of the transmitter architecture optimized for GMSK modulation for 8-PSK modulation, where distortion introduced in the GMSK transmitter architecture is compensated for by modifying the amplitude component of the 8-PSK signal. The patent application was filed October 7th 1998, and first granted in US August 2000.