Until such a path exists various options are available such as using multiple
processors and/or FPGA fabric [42]. The SDR Forum [43] defines five tiers of solutions, the
reader should consult the variety of references for further reading. The most likely path to take form
is to have a solution possible to support a variety of predefined standards. This joint optimization
across all standards may be possible and still allow for software programmability across the same
platform.
The most likely multistandard terminal will consists of GSM, WCDMA/LTE, Bluetooth, and
Wireless LAN. Generally speaking, the radio access technologies can be divided into short range
338 CHAPTER SIX
LPF X
BPF
X LPF
ADC
ADC
Baseband
Section
~
LNA GCA 90?°
LPF DAC
RI(t)
RQ(t)
AFC
COS[wct + ??†wt]
LPF DAC
AGC
DC Offset
FIGURE 6.50 Direct conversion receiver architecture.
communications (i.e., Bluetooth) to enable hands-free voice calls, remote keyboards and mice, allow
FM music, as well as a variety of other applications. Also, data transfer (i.e.,WiFi) would be used by
portable computing devices such as PDAs, Smart Phones, laptops, and so on. Lastly, the cellular
umbrella is essential to accommodate mobility, not to mention roaming where we have specifically
mentioned GSM/WCDMA/LTE.
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