Hiperlan 2
A new set of standards are under
construction for a new version of HIPERLAN - HIPERLAN2. The idea
of HIPERLAN2 is to be compatible with ATM.
There is also undergoing work to
establish global sharing rules. The WINForum for NII/SUPERNET in the US aim to support HIPERLAN 1 and
HIPERLAN 2. This effort involves interaction between ETSI RES10,
WINForum, ATM Forum.
Figure 2 - The future of
HIPERLAN
Reference Hiperlan 2 Configuation
The reference configuration consists of
- Data scrambling
User data is exor-ed with the output of a 7-bit Linear Feedback shift register
LSFR with polynomial X7 + x4 + 1 is used to randomize
the data. The sequence length is 127.
- FEC error coding
Convolutional encoding with puncturing. The length of the encoder is 6. The
generator polynomials are 133 (oct) and 171 (oct) for two outputs per input
symbol. Pucturing is used for code rates other than 1/2, namely 3/4 and 9/16.
- Interlaeving
Two permutations
- Mapping bits to QAM
BPSK, QPSK, 16 or 64 QAM are used.
- OFDM
64 subcarriers. sampling rate is 1/T = 20 MHz. The useful symbol duration
is 64T or 3.2 microsecond. The prefix has a duration of 16T.
Optionally, a prefix of 8T can be used. So the total frame (OFDM symbol)
duration is 80T (4 microsec) or 72T. 48 subcarriers carry data.
4 subcarriers are used as pilots to estimate the channel. Hence only 52 of the
64 subcarriers are actually in use, the others contain
no signal. In the specification these are numbered -26, -25, ..., 26.
Subcarriers used
for pilots are -21, -7, 7, and 21. No signal is transmitted at subcarrier 0 (DC).
The subcarrier spacing equals 312.5 kHz.
- PHY burst transmission
Different burst formats for up and downlink
- Radio transmission
