CoFIP Pilot Sequences

Document Number: IEEE C80216m-09_2239r2

Date Submitted: 2009-17-05

Source:Padmanabhan M S, Kiran Kuchi, J. Klutto Milleth, Sivakishore Voice:CEWiT, India E-mail:

kkuchi@cewit.org.in, klutto@cewit.org.in

Venue: Comments on P802.16m/D2 (15.3.11.3.3)

Base Contribution: None

Purpose: To discuss and adopt the proposed text in D3

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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

CID = 0 CID=1 CID=2

s

t -->

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 six COFIP pilot tones shall be obtained from the pilot codebook C defined in Table xxx.

The code used in a PRU in a cell with cluster_ID = k is C( (s+t+k) mod 7), where ‘s’ is the physical PRU index and ‘t’ is the physical subframe index, and C(i) is the ith code defined in Table xxx with i=0,1,…6. Each entry of the sequence corresponding to C(i) shall be used to modulate the 6-pilot tones in the order shown in Figure xxx, yyy and zzz where P(j) denotes the jth entry of C(i)

Table xxx Pilot Code Book for CoFIP

Pilot Code Sequence

C(0) [-1 -1 1 1 1 -1]

C(1) [-1 1 -1 -1 1 1]

C(2) [-1 1 1 1 -1 1]

C(3) [1 -1 -1 1 1 1]

C(4) [1 -1 1 -1 -1 1]

C(5) [1 1 -1 1 -1 -1]

C(6) [1 1 1 -1 1 -1]

X P(0) X X P(1) X

X P(2) X

P(3) X X

X X P(4) X X

P(0) X X P(1) X X

X X P(2)

X P(3) X

X P(4) X X P(5) X

X X P(0) X X P(1)

P(2) X X

X X P(3)

P(4) X X P(5) X X

Figure xxx – Pilot Modulation for CoFIP Tones for AAI sub frames with 6 OFDM symbols

Pilot pattern set 0 Pilot pattern

set 1Pilot pattern

set 2

6 symbols

X P(0) X X P(1) X X

X P(2) X X

P(3) X X P(3)

X X P(4) X X X

P(0) X X P(1) X X P(0)

X X P(2) X

X P(3) X X

X P(4) X X P(5) X X

X X P(0) X X P(1) X

P(2) X X P(2)

X X P(3) X

P(4) X X P(5) X X P(4)

Figure yyy – Pilot Modulation for CoFIP Tones for AAI sub frames with 7 OFDM symbols

Pilot pattern set 0 Pilot pattern

set 1Pilot pattern

set 2

7 symbols

X P(0) X X P(1)

X P(2) X X

P(3) X P(4) X

X X P(5) X X

P(0) X X P(1) X

X X X P(2)

X P(3) X X

X P(4) X X P(5)

X X P(0) X X

P(1) X P(2) X

X X X P(3)

P(4) X X P(5) X

Figure zzz - – Pilot Modulation for CoFIP Tones for AAI sub frames with 5 OFDM symbols

……………………..End of Text……………………………………………………….

Pilot pattern set 0 Pilot pattern

set 1Pilot pattern

set 2

5 symbols