S802.16m-08/319r1
New Preamble Sequence Design Using Quasi Complete Complementary Codes
for IEEE 802.16m
Document Number: S802.16m-08/319r1
Date Submitted:
May 05, 2008
Source:
Pei-Kai Liao (pk.liao@mediatek.com) and Paul Cheng (paul.cheng@mediatek.com)
MediaTek Inc. No. 1 Dusing Rd. 1 Hsinchu Science Park Hsinchu City 300 Taiwan;
Chao-Yu Chen (d919609@oz.nthu.edu.tw), Kuei-Ying Lu and Chi-Chao Chao (ccc@ee.nthu.edu.tw)
Institute of Communications Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan;
Yih-Guang Jan (yihjan@ee.tku.edu) and Yang-Han Lee (yhlee@ee.tku.edu.tw)
Tamkang University;
Shiann-Tsong Sheu (stsheu@ce.ncu.edu.tw)
National Central Univeristy
Venue:
Macao, China
Base Contribution:
IEEE C802.16m-08/319r1
Purpose:
Propose to be discussed and adopted by TGm for the use in Project 802.16m SDD.
Notice:
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Introduction
• Motivation
– Non-structural code sequence for 802.16e preamble
• Memory for the storage of code sequence
• Longer searching time of code matching
– Structural code sequence with low PAPR, low crorsscorrelation and similar performance is desired
• Purpose and Summary
– A new code sequence using QCCC is proposed for
802.16m preamble
– Propose to be discussed and included in 802.16m SDD
Design Considerations
• Mathematical structure
– Structural code sequences reduce hardware complexity of
transceiver design
• Low PAPR
– To maximize transmission power efficiency, code
sequences with low PAPR is desirable
• Large peak to cross-correlation ratio
– Large peak to cross-correlation ratio reduces the possibility
of misjudgment of code matching
• More code sequences
– More Cell_ID is desired
Auto-Complementary Code
• Definition: A set of M sequences c1,c2,…,cM of
length n is called an ACC of order M or Golay
complementary set of order M, if the autocorrelation functions satisfy
Aperiodic Auto-correlation Function
Auto-correlation is all zero except the peak at zero time shift
Complete Complementary Code
• Definition: The M sets of M length-n sequences
{c11,c21,…,cM1},…,{c1M,c2M,…,cMM} are called a
complete complementary code of order M if every set
is an ACC and every two distinct sets satisfy
Cross-correlation is all zero;
Auto-correlation is all zero except the peak at zero time shift
Problem: the number of set, M, is limited by the length!!
(More code sets require longer code length, not feasible)
Quasi Auto-Complementary Code
• Definition: We call a pair of length-n sequences {c1,
c2} a quasi auto-complementary code of order 2 if
2n 
n 1

u =  n 1
 (c1 ; u )   (c2 ; u ) = 2n 2 .
Auto-correlation is of a small positive value
the peak at zero
time this
shift set is in
theexcept
left equality
holds,
• If
fact an autocomplementary code (ACC) of order 2 or called a
Golay pair
Quasi Complete Complementary Code
• Definition: The sets of length-n pair {c11,c21},
{c12,c22}, …, {c1M,c2M} are called a quasi complete
complementary code of order M if every pair is a
QACC and every two distinct pairs satisfy
0
n 1

u =  n 1
 (c1j , c1k ; u )   (c2j , c2k ; u ) = 2n 2
Cross-correlation is of a small positive value;
Auto-correlation is all of a small positive value
except the peak at zero time shift
for any u; j, k=1,2,…,M; j≠k.
More code sets with reasonable code length, feasible!!
Construction of QCCC
Properties of QCCC
• Comparisons of PAPR and cross-correlation between QCCC-based and
PN-based 802.16e preambles for 10 MHz (1024 sub-carriers)
Code length 256
Code length 284
Preamble Structure – Cascade over
Frequency Domain
C1
C2
Constructed QCCC code sequence is modulated by BPSK at sub-carriers and interleaved by 3
Simulation Results
Performance comparison between PN-based and QCCC-based preambles on modified
ITU Pedestrian B channel with velocity 3km/hr
Simulation Results
Performance comparison between PN-based and QCCC-based preambles on modified
ITU Vehicular A channel with velocity 30km/hr
Simulation Results
Performance comparison between PN-based and QCCC-based preambles on modified
ITU Vehicular A channel with velocity 120km/hr
Conclusion
• A code sequence with mathematical structure for 16m
preamble is proposed
– It waives the memory storage of all code sequences
– It enables the possibility of more efficient code matching
algorithm instead of full search
• More code sequences for Cell_IDs
• Performance of the proposed code sequence, QCCC,
is close to that of 16e PRBS