563489578934

Sec. 8–13 Study-Aid Examples 657
TABLE 8–18
WIMAX STANDARDS
Item Licensed Service Unlicensed Service
Band 2.5 GHz 5.5 GHz
Frequencies 2.5 to 2.69 MHz * 5.25 to 5.58 GHz
Channel bandwidth 20 to 40 MHz 20 to 40 MHz
Purchase spectral space Yes No
Power output up to about 20 W 4 W EIRP
Range 30 miles 10 miles
Modulation OFDM OFDM
Dual channels via FDD TDD
Data rate (maximum) 108 Mb/s 108 Mb/s
Advantages Less interference, Better NLOS reception Fast rollout, Lower cost
*Additional WiMAX frequency bands are likely to be designated by the FCC.
FDD = Frequency-division duplexing (i.e., two frequency channels required—one for uplink and one for downlink)
TDD = Time-division duplexing (i.e., one frequency channel required, but two time slots required—one for uplink
and one for downlink)
NLOS = Non Line-Of-Sight
8–12 SUMMARY
A wide range of wire and wireless systems were studied. Modem telephone systems with
digital central offices and remote terminals were described. Standards for data transmission
via DSL, as well as standards used for POTS, were given. Specifications of PSTN systems
were listed for transmission via fiber-optic cable and via satellite. Satellite radio broadcast
services were discussed. Noise figure and effective input-noise temperature for wireless
receivers were defined. Case studies of link budgets were presented. 1G, 2G, 3G, and 4G
standards for cellular phone systems were examined. Analog and digital TV systems were
studied. Standards were given for analog NTSC TV and digital ATSC TV including SDTV
and HDTV programming. Cable data modems were discussed. Standards for WiFi and
WiMAX wireless data networks were given and their operation was discussed.
8–13 STUDY-AID EXAMPLES
SA8-1 Link Budget for a DSS Receiver Compute the link budget for a digital TV satellite
system that is similar to the DSS (digital satellite system) system that was described in Sec. 8–5.
The DSS satellite is located in a geostationary orbit at 101° W longitude above the equator. Assume
that the downlink receiving site is Gainesville, FL, located at 82.43° W longitude and 29.71° N latitude.
The DSS satellite transmits downlink signals in the Ku band (12.2–12.7 GHz) using 16
transponders. Each transponder has a bandwidth of 24 MHz and an EIRP of 52 dBw in the direction
of the United States and, in particular, to Gainesville, FL. Each transponder radiates a QPSK signal
with a data rate of 40 Mbs. The receiving system consists of (1) an 18-inch-diameter parabolic
antenna with an attached (2) low-noise block downconverter (LNB) that converts the Ku band
input down to 950 to 1450 MHz, (3) a transmission line that connects the LNB to (4) a receiver that