Another reason is, historically speaking, the IC manufacturers of WAN,
WLAN, and PAN devices have been different.There are very few successful cases of one manufacturer
providing all of the above-mentioned solutions. However, the landscape has been changing and
continues to change as time, services, capabilities, and demands rise.
In its simplest form, SDR refers to having the capability to reconfigure the terminal (i.e., handset)
by software. More specifically the software must also encompass the protocol stack plus applications.
Moreover, we must state that there will be some functionality (at least initially) in dedicated HWwith
a roadmap to be reconfigurable at some later date. In the simplest form, SDR entails being able to
change the personality of the terminal (or device) by downloading or changing the software that
resides on the device. This requires control not only over the RF, but also over the baseband signal
processing, of which includes the layer 1 as well as the higher layers.
A most likely path to achieve an SDR terminal
would be to start at the top of the protocol stack and
work your way down. Once you get close to the physical
layer, you are essentially operating at or below the
RTOS so care must be taken when considering various
implementations.
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