X hits on this document

PDF document

Performance Evaluation of WiMAX/IEEE 802.16 OFDM Physical Layer - page 39 / 107

275 views

0 shares

0 downloads

0 comments

39 / 107

Table 4.1:OFDM Symbol Parameters

Type

Primitive

Derived

Parameters Nominal Channel Bandwidth, BW Number of Used Subcarrier, Nused Sampling Factor, n Ratio of Guard time to useful symbol time, G NFFT(smallest power of 2 greater than Nused) Sampling Frequency, Fs Subcarrier Spacing, f Useful Symbol Time, Tb CP Time, Tg OFDM Symbol Time, T s Sampling Time

Value 1.75 MHz 200 8/7 1/4 ,1/8, 1/16, 1/32 255 Floor(n.BW/8000) X 8000 Fs/NFFT 1/ f G.Tb Tb+Tg Tb/NFFT

4.2 Physical Layer Setup

The structure of the baseband part of the implemented transmitter and receiver is shown in Figure 4.1. This structure corresponds to the physical layer of the IEEE 802.16­2004 WirelessMAN­OFDM air interface. In this setup, we have just implemented mandatory features of the specification, while leaving the implementation of optional features for future work. Channel coding part is composed of three steps­ randomization, Forward Error Correction (FEC) and interleaving. FEC is done in two phases through the outer Reed­Solomon (RS) and inner Convolutional Code (CC). The complementary operations are applied in the reverse order at channel decoding in the receiver end. The complete channel encoding setup is shown in Figure 4.2 while corresponding decoding setup is shown in Figure 4.3. Through the rest of the sections, the individual block of the setup will be discussed with implementation technique.

28

the

Document info
Document views275
Page views281
Page last viewedMon Dec 05 23:59:30 UTC 2016
Pages107
Paragraphs1573
Words17747

Comments