51 Software defined radio features.
Some of the reasons for the segmentation are given in the block diagram. We know that the multistandard
terminal would need to operate in different frequency bands. These bands will not only differ
within the geography of use, but also from one country to another. These bands will have different
bandwidths and operating specifications (i.e., FCC, and so on) that need to be met.
The baseband would need to have a modem to support various modulation schemes and widely
varying data rates. The dynamic range and quantization effects should be carefully considered when
jointly optimizing the multistandard terminal.
Lastly, the software would need to perform demanding signal processing functions for the various
modulation schemes and at the widely varying data rates. We have focused our attention to radio
access technologies that cover Personal Area Network (PAN) to Wide Area Network (WAN). This
wide variation will be visible in the varying channel conditions the user experiences when the terminal
is utilized. Since the channel conditions dictate the complexity of the receiver signal processing,
the terminal will have differing levels of signal processing demands.
In Fig. 6.52 we show a hierarchical diagram of the software architecture.
Pages:
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560