TABLE 75.1 Specifications of TDMA and CDMA Systems TDMA CDMA Bandwidth per channel 1.23 MHz Time slots Speech coder 8 kbps(max )a variable rate vocoder Modulation T/4-DQPSK Forward radio channels Pilot(1)sync(1), Paging(7) 8 kbps-VSELP code traffic channels(55), total 64 vector sum excited LPC) channels Channel coding ate 1/2 convolutional(13 kbps) Reverse radio channels (9), traffic channels (55) Total transmit rate 48 kbps per channel Power control rd, reverse Diversity LPC linear predictive code. Cell splitting: When a cell provides a maximum of 60 radio channels and all are used during bus hours, the cell has to be split into smaller cells in order to provide more radio channels, normally reducing by four subcells. Each subcell 60 channels. The total area of an original cell will provide 240 radio channels which is four times higher Spectrum Allocation in the United States, Europe, and Japan: In the United States there is 50 MHz of ectrum allocated to cellular radio within 800-900 MHz. Based on duopoly, each city has two licensed operators. Each one operates on a 25-MHz band. There are two bands, Band A and Band B. Each band consists of 416 channels. The channel bandwidth is 30 kHz. Among 416 channels, 21 channels are used for setting up and 395 are used for voice channels Analog: The frequency management of both Band A and Band B is shown in Table 75.5. Digital: There are two potential systems, TDMA and CDMA shown in Table 75.1 In Europe the spectrum allocation is as shown in Table 75.2 and 75.3 In Japan the spectrum allocation is as shown in Table 75.4 TABLE 75.2 Specification of Three European Systems TACS NMT* Transmission frequency(kHz) Base statio 935960 463-467.5 461.3-465.74 Mobile station 890-915 453-457.5 451.3-455.74 Spacing between transmission Spacing between channels(kHz)25 Number of channels 0 30 Type of modulation 4 Type of modulation FSK ±6.4 ±3.5 ±25 Data transmission rate(kbps) 8 .28 essage protection lesage is sent again decision is employed when an error g to the is detected ontent of the s TACS=total access cellular system; NMT = nordic mobile telephone c2000 by CRC Press LLC© 2000 by CRC Press LLC • Cell splitting: When a cell provides a maximum of 60 radio channels and all are used during busy hours, the cell has to be split into smaller cells in order to provide more radio channels, normally reducing the cell by using a half radius. As a result a cell will be covered by four subcells. Each subcell provides 60 channels. The total area of an original cell will provide 240 radio channels which is four times higher in capacity as compared with the original cell capacity before splitting. Spectrum Allocation in the United States, Europe, and Japan: In the United States there is 50 MHz of spectrum allocated to cellular radio within 800–900 MHz. Based on duopoly, each city has two licensed operators. Each one operates on a 25-MHz band. There are two bands, Band A and Band B. Each band consists of 416 channels. The channel bandwidth is 30 kHz. Among 416 channels, 21 channels are used for setting up and 395 are used for voice channels. • Analog: The frequency management of both Band A and Band B is shown in Table 75.5. • Digital: There are two potential systems, TDMA and CDMA shown in Table 75.1. In Europe the spectrum allocation is as shown in Table 75.2 and 75.3. In Japan the spectrum allocation is as shown in Table 75.4. TABLE 75.1 Specifications of TDMA and CDMA Systems TDMA CDMA Bandwidth per channel 30 kHz Bandwidth per channel 1.23 MHz Time slots 3 Speech coder 8 kbps(max.)—a variable rate vocoder Modulation p/4-DQPSK Forward radio channels Pilot (1) sync (1), paging (7), Speech coder 8 kbps—VSELP code traffic channels (55), total 64 (vector sum excited LPC*) channels Channel coding Rate 1/2 convolutional (13 kbps) Reverse radio channels Access (9), traffic channels (55) Total transmit rate 48 kbps per channel Power control Forward, reverse Equalizer Up to 40 ms Diversity Rake receiver * LPC = linear predictive code. TABLE 75.2 Specification of Three European Systems Analog England Scandinavia West Germany System TACS* NMT* C450 Transmission frequency (kHz) Base station 935–960 463–467.5 461.3–465.74 Mobile station 890–915 453–457.5 451.3–455.74 Spacing between transmission 45 10 10 and receiving frequencies (MHz) Spacing between channels (kHz) 25 25 20 Number of channels 1000 180 222 (control channel 21 ¥ 2); interleave used Coverage radius (km) 2–20 1.8–40 5–30 Audio signal Type of modulation FM FM FM Frequency deviation (kHz) ±9.5 ±5 ±4 Control signal Type of modulation FSK FSK FSK Frequency deviation (kHz) ±6.4 ±3.5 ±2.5 Data transmission rate (kbps) 8 1.2 5.28 Message protection Principle of majority Receiving steps are Message is sent again decision is employed predetermined when an error according to the is detected content of the message * TACS = total access cellular system; NMT = nordic mobile telephone