ENC3250 Solutions pg 63

ENC3250 Solutions pg 63 - a2. One 16-PPM symbol represents...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: a2. One 16-PPM symbol represents 4 bits. Therefore, the period for symbol transmission is 4 µs. There is one pulse in each symbol, so the average time between pulses is 4 µs. a3. Each symbol consists of 16 pulse positions, with only one pulse present. If the adjacent symbols are 0000000000000001 and 1000000000000000, then the time between pulses is 4/16 = 0.25 µs. a4. If the adjacent symbols are 1000000000000000 and 0000000000000001, then the time between pulses is 31 × 0.25 = 7.75 µs b1. The 4-PPM scheme is for the 2-Mbps data rate. Therefore, the period for bit transmission is 1/(2 × 106 ) = 0.5 µs. b2. One 4-PPM symbol represents 2 bits. Therefore, the period for symbol transmission is 1 µs. There is one pulse in each symbol, so the average time between pulses is 1 µs. b3. Each symbol consists of 4 pulse positions, with only one pulse present. If the adjacent symbols are 0001 and 1000, then the time between pulses is 1/4 = 0.25 µs. b4. If the adjacent symbols are 1000 0001, then the time between pulses is 7 × 0.25 = 1.75 µs 14.4 Each subcarrier can operate at 250 kbaud, that is, 0.25 × 106 signal elements per second. For the first row in Figure 14.6d, BPSK is used, which corresponds to one bit per signal element. With a code rate of 1/2, each data bit is encoded as 2 code bits. Thus, the effective data rate on each subcarrier is 125 kbps. With 48 subcarriers, this results in a data rate of 48 × 125 kbps = 6 Mbps. For the second row in Figure 14.6d, a code rate of 3/4 is used, meaning 3 data bits are coded as 4 code bits. Thus, the effective data rate on each subcarrier is 0.75 × 250 = 187.5 kbps. The overall data rate is 48 × 187.5 = 9 Mbps. For the third row, the use of QPSK allows two bits per signal element, so that the 250-kbaud rate per subcarrier becomes 500 kbps. Using the same reasoning as for the first row in the table, this results in a data rate of 12 Mbps. The remaining rows can be easily calculated. -63- ...
View Full Document

This note was uploaded on 02/20/2012 for the course ENC 3250 taught by Professor Dr.timothycerner during the Fall '11 term at UNF.

Ask a homework question - tutors are online