CoFIP Pilot Sequences
Document Number: IEEE C80216m-09_2239r3
Date Submitted: 2009-17-05
Source:
Padmanabhan M S, Kiran Kuchi, J. Klutto Milleth, Sivakishore
CEWiT, India
Voice:
E-mail:
[email protected],
[email protected]
Venue: Comments
on P802.16m/D2 (15.3.11.3.3)
Base Contribution: None
Purpose: To discuss and adopt the proposed text in D3
To discuss in TGm for appropriate action. Notice:
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CoFIP pilot sequences
specification
Pilot sequences for CDR with CoFIP

The pilot sequences assigned to different cells should
have low cross correlation within the space of an RB.

Some of the possibilities are:

Use of short pilot sequences, which have low cross-correlation within a
localized resource unit.

Use of long PN sequences

Results in increased cross correlation
Short PN sequence




Seven PN sequences are generated using an LFSR with the
characteristic polynomial X3+X +1
The first 6 samples of a sequence is used for deriving the 6 pilots with
in a PRU
Definitions:

A cluster is a collection of 3 sectors and is assigned unique cluster id = CID

PRU index ‘s’ in frequency and sub-frame number ‘t’ in time.
Pilot codebook C = { c(0),c(1),c(2), c(3), c(4),c(5), c(6) } is defined in
table 1.
Pilot codebook
Table 1
Pilot sequence cycling

Pilot sequence cycling in time and/or frequency is implemented to
exploit the advantage of interference averaging on the pilots. The
pilot code used in a cell with CID = k is C( (s+t+k)%7), where C(i) is
the ith code of the set of codes C. i=0,1,…6
t -->
s
CID = 0
CID=1
CID=2
CDR Performance comparison between short
and long PRBS
Proposed Text
……………………..Start of Text……………………………………………………….
Section 15.3.11.3.3, Page 541, line 56
In Type 1 OL MIMO region, the pilot sequence used to modulate the CoFIP pilot
subcarriers shall be obtained from the set of pilot modulation sequences
defined in Table xxx. The sequence index used for modulation of PRU pilot
subcarriers is derived from i= [(s+t+mod(IDCell,7)) mod 7], where s is the
physical PRU index, t is the physical subframe index. Each entry of the
sequence shall be used to modulate the pilot subcarriers in the order shown
in Figure xxx, yyy and zzz where P(j) denotes the jth entry of chosen pilot
sequence
Sequence
index
Pilot Modulation
Sequence
0
[-1 -1 1 1 1 -1]
1
[-1 1 -1 -1 1 1]
2
[-1 1 1 1 -1 1]
3
[1 -1 -1 1 1 1]
4
[1 -1 1 -1 -1 1]
5
[1 1 -1 1 -1 -1]
6
[1 1 1 -1 1 -1]
Table xxx Pilot Modulation Sequences for CoFIP
6 symbols
18 contiguous subcarriers
P(0)
X
X
P(1)
X
X
X
P(0)
P(2)
X
X
P(2)
X
X
P(3)
X
P(3)
X
P(4)
X
X
P(5)
Pilot pattern set 0
X
X
X
X
X
X
P(4)
X
P(1)
X
X
X
P(0)
X
X
X
P(2)
X
X
X
X
X
P(3)
X
P(4)
Pilot pattern set 1
X
X
P(5)
X
Pilot pattern set 2
Figure xxx – Pilot Modulation for CoFIP Tones for AAI sub frames with 6
OFDM symbols
P(1)
X
7 symbols
18 contiguous subcarriers
P(0)
X
X
P(1)
X
X
P(0)
X
P(0)
P(2)
X
X
P(2)
X
X
X
P(3)
X
X
P(3)
X
X
X
P(4)
X
X
P(5)
X
Pilot pattern set 0
X
X
X
X
P(4)
X
P(1)
X
X
X
X
P(2)
X
X
P(2)
X
P(3)
X
X
P(3)
X
X
X
P(4)
Pilot pattern set 1
X
X
X
P(0)
X
X
P(5)
Pilot pattern set 2
Figure yyy – Pilot Modulation for CoFIP Tones for AAI sub frames with 7
OFDM symbols
X
X
P(1)
X
X
P(4)
5 symbols
18 contiguous subcarriers
P(0)
X
P(1)
X
X
X
X
X
P(2)
X
P(3)
X
X
X
X
X
P(4)
Pilot pattern set 0
P(0)
X
X
P(1)
X
X
P(2)
X
X
X
P(3)
X
P(4)
P(5)
X
P(5)
X
X
P(0)
X
X
P(1)
X
P(2)
X
X
X
X
X
P(3)
X
P(4)
X
P(5)
X
Pilot pattern set 1
X
X
Pilot pattern set 2
Figure zzz - – Pilot Modulation for CoFIP Tones for AAI sub frames with 5 OFDM symbols
……………………..End of Text……………………………………………………….