Re: [STDS-802-16] Fwd: Question regarding 802.16-2004 standard
Hi,
The example is wrong, and was corrected in the latest MAINT draft, page 115
(and I have a feeling that it may be corrected again).
Regards,
Itzik.
-----Original Message-----
From: owner-stds-802-16@LISTSERV.IEEE.ORG
[mailto:owner-stds-802-16@LISTSERV.IEEE.ORG] On Behalf Of Forwarded by
Sent: Wednesday, March 09, 2005 6:08 PM
To: STDS-802-16@LISTSERV.IEEE.ORG
Subject: [STDS-802-16] Fwd: Question regarding 802.16-2004 standard
This note is from ERNEST KURNIAWAN
<ernest_kr@pmail.ntu.edu.sg>. Feel free to respond.
Roger
>Dear Marks,
>
>I have a question regarding 802.16-2004 standards. I tried to build the
>system simulation based on the specification on the
>802.16-2004 standards. And I tried putting in the test Input in the
>example given in the standard (pp. 618-700 section 8.4.9.4.4). But
>somehow, I get different output on one of its building block, so I need
>to clarify whether my block design is wrong or if there are some steps
>I missed out. The following are the detail of my block processing:
>· For the Randomizer block, I managed to
>process the "Input Data" to "Randomized Data" by using PRBS constructed
>as in Figure 253, and initializing the randomizer with the OFDMA Symbol
>Offset (=35 in our example) for the first 10 digits (b14..b5) and
>Sub-channel offset (=6 in our example) for the last 5 digits (b4..b0).
>· For the FEC block, I managed to
>process the "Randomized Data" to "Convolutional encoded Data" by using
>convolutional encoder with rate=½ as depicted in Figure 255, and
>applying tail biting algorithm for the initialization value.
>· Now, my problem starts on the
>Interleaver block. I used the equation (130) and
>(131) on page 615 to compute the interleaved bit index with the
>following values as the constants:
>o Ncbps = 192 (which is the number of
>bits contained in the message to be interleaved)
>o d = 16
>o Ncpc = 2 (which is the number of bits per symbol in QPSK
modulation)
>o s = 1 (which is half the value of Ncpc)
>But the interleaved value I obtain is "6D B7 EF FD B8 68 38 C9 27 9E D4
>A3 AE FC 15 DE FE B9 68 AD 68 56 19 9A". Interestingly, when I set Ncpc
>to 4 (by assuming that we use 16-QAM instead), I managed to get the
>value as in the example. >> So is there anything I missed out or any
>parameter I wrongly set here?
>· From this point, I assumed that the
>information I get as the interleaved data is the same as what the
>example give, and keep maintaining the QPSK modulation configuration.
>· For the Constellation Mapper block, I
>managed to get the output right by applying the constellation depicted
>in Figure 263 for QPSK, and taking the Interleaved Data given in the
>example as its input.
>· Now, performing sub-channel allocation
>is the biggest confusion that I have here. In the example, it is stated
>that the logical slot
>6 is mapped onto physical sub-channel 16 in the first time slot and
>physical sub-channel 17 in the second time slot. So, by applying
>equation
>(113) on page 569, with parameter s set to 16 and 17 (sub-channel
>number), and parameter UL_IDcell set to 5 (IDcell number), I managed to
>obtain the tiles corresponding to the two physical sub-channels to be
>used. For the first sub-channel, the six tiles spans across OFDMA
>symbol index 35-37, and sub-carrier range of 448-451; 512-515; 984-987;
>1189-1192; 1505-1508;
>1753-1753 correspondingly. The second
>sub-channel, the six tiles spans across OFDMA symbol index 38-40, and
>sub-carrier range of 232-235; 704-707; 908-911; 1225-1228; 1473-1476;
>1813-1816 correspondingly. Taking the values depicted in the example
>given, I rewrite it on the table as can be seen on the attached file.
>There are two doubts that I have in this
>scenario:
> >> On the second sub-channel, it is noted that the pilot location
>does not conform to the structure depicted in figure 236.
> >> Applying the reordering sequence as explained in page 570 and
>equation (114), I could not manage to obtain the same mapping as what
>is given in the example. Here, I used Nsubcarriers = 48 (as there are
>48 data sub-carriers in each sub-channel), and parameter s set to 16
>and 17 (for the sub-channel 16 and
>17 correspondingly). I would appreciate if you could elaborate more on
>the reordering process and equation (114) in page 570.
>
>Please let me know if you need any further details on how I obtained
>the above value. Your help is greatly appreciated. Thank you very much
>in advance.
>
>Regards,
>Ernest.