1. ETRI Proposal to IEEE 802.11 TGn
August 2004
ETRI Proposal to IEEE TGn
Heejung Yu, Taehyun Jeon, Sok-Kyu Lee,
Myung-Soon Kim, Eun-young Choi, Seung-Ku Hwang
Next Generation Wireless LAN Research Team
ETRI
{heejung, thjeon, sk-lee, mskim75, eychoi,
Heejung Yu, ETRI

2. Contents Proposed technologies for >200Mbps in PHY Detail Standard
August 2004
Contents
Proposed technologies for >200Mbps in PHY
MIMO-OFDM
Dual band
Detail Standard
Simulation Results
Conclusions
Heejung Yu, ETRI

3. Proposed technologies
August 2004
Proposed technologies
for >200Mbps in PHY
Heejung Yu, ETRI

4. Candidate technologies
August 2004
Candidate technologies
Legacy IEEE a => 20MHz BW, 54Mbps
To achieve more than 100Mbps at the top of the MAC SAP, we need x3 or x4 data rate.
Depending on MAC efficiency
To extend x4 transmission
MIMO (improve spectral efficiency)
Bandwidth extension
High order modulation
High rate coding
Heejung Yu, ETRI

5. MIMO Data rate can be increased with the number of Tx antennas.
August 2004
MIMO
Data rate can be increased with the number of Tx antennas.
We have some problem in using 3 and more stream.
Implementation complexity
Limitation on antenna spacing, high MIMO channel correlation can be a problem.
So, we cannot fully rely on the MIMO technology for 3 or 4x data rate.
Heejung Yu, ETRI

6. Bandwidth Extension Clock doubling Dual band New OFDM parameter
August 2004
Bandwidth Extension
Clock doubling
Dual band
New OFDM parameter
64 subcarrier
40MHz
64 subcarrier
64 subcarrier
40MHz
20MHz
xxx subcarrier
40MHz
Heejung Yu, ETRI

7. Bandwidth Extension Clock doubling Dual band New OFDM parameter
August 2004
Bandwidth Extension
Clock doubling
802.11a modem with clock switching function
Protection mechanism for compatibility
Dual band
802.11a modem (2 units) or a modem with some change( using 128 point FFT)
Compatible with legacy a (refer specification part)
New OFDM parameter
802.11a + new modem with new OFDM parameters( # of subcarrier, # of CP, etc.)
Heejung Yu, ETRI

8. Dual-band Merits Demerits More flexible implementation
August 2004
Dual-band
Merits
More flexible implementation
We extend threefold, fourfold BW systematically by increasing number of FFT or FFT size.
Compatible preamble and SIGNAL field is possible.
More robust to DC-offset (11 DC-carrier)
Demerits
Reduce the number of channel
In some countries, only 20MHz channel usage is allowed
Heejung Yu, ETRI

9. Max. data rate (mandatory)
August 2004
Max. data rate (mandatory)
# of Tx and Rx antennas = 3
We use 2 Tx antennas out of 3 antennas (include Tx antenna selection option)
# of Tx streams (MIMO gain) = 2
Dual-band (data rate gain) = 2
Achievable Data Rate = 2 x 2 x (legacy rate)
= 216Mbps
In optional mode, 288Mbps (256-QAM, 3/4 code rate) is possible.
Heejung Yu, ETRI

10. Details of ETRI PHY specification
August 2004
Details of ETRI PHY specification
Heejung Yu, ETRI

11. Main features Compatible with IEEE 802.11a Bandwidth : 20 or 40MHz
August 2004
Main features
Compatible with IEEE a
Bandwidth : 20 or 40MHz
Multiple antennas : 2 Tx antennas
3 Rx antennas are recommended.
Tx antenna selection is available.
Modulation : Legacy OFDM, SDM-OFDM, STBC-OFDM
Data Rate
20MHz BW:6,9,12,18,24,36,48,54,72,96,108,128,144 Mbps
40MHz BW : doubled
Heejung Yu, ETRI

12. TXVECTOR, RXVECTOR BANDWIDTH and MODE are added in TX/RX VECTOR
August 2004
TXVECTOR, RXVECTOR
BANDWIDTH and MODE are added in TX/RX VECTOR
BANDWIDTH : PHY can use consecutive two 20MHz band for higher data rate.
MODE : transmission scheme
Legacy OFDM
SDM-OFDM (Spatial Division Multiplexing)
STBC-OFDM (Space-Time Block Code)
Heejung Yu, ETRI

13. Frame Format Legacy OFDM STBC-OFDM, SDM-OFDM August 2004
Heejung Yu, ETRI

14. PCLP Preambles Legacy OFDM STBC-OFDM, SDM-OFDM Even Even Even Odd Odd
August 2004
PCLP Preambles
Legacy OFDM
STBC-OFDM, SDM-OFDM
Even
Even
Even
Odd
Odd
Odd
Odd
Even
Heejung Yu, ETRI

15. Preamble Pattern (Single Antenna Single Band)
August 2004
Preamble Pattern (Single Antenna Single Band)
Short preamble
Long preamble
Heejung Yu, ETRI

16. Preamble Pattern (Dual Antenna Single Band)
August 2004
Preamble Pattern (Dual Antenna Single Band)
Short preamble
(Ant 0 : even subcarriers, Ant 1 : odd subcarriers)
Ant 0
Ant 1
Long preamble
Heejung Yu, ETRI

17. Preamble Pattern (Single Antenna Dual Band)
August 2004
Preamble Pattern (Single Antenna Dual Band)
Short preamble (concatenation of single band preambles)
Long preamble (concatenation of single band preambles)
Heejung Yu, ETRI

18. Preamble Pattern (Dual Antenna Dual Band)
August 2004
Preamble Pattern (Dual Antenna Dual Band)
Short preamble (concatenation of single band preambles)
Ant 0
Ant 1
Long preamble (concatenation of single band preambles)
Heejung Yu, ETRI

19. Preamble Properties Repetition property is maintained
August 2004
Preamble Properties
Repetition property is maintained
Same auto-correlation property
PAPR for single band preamble
Legacy-OFDM mode : 2.09dB (short), 3.17dB(long)
SDM/STBC-OFDM mode
Antenna 0 : 4.69dB(short), 5.58dB(long)
Antenna 1 : 4.69dB(short), 5.85dB(long)
PAPR for dual band preamble
Legacy-OFDM mode : 5.10dB (short), 6.18dB(long)
Antenna 0 : 5.80dB(short), 7.05dB(long)
Antenna 1 : 5.80dB(short), 8.86dB(long)
Cross correlation between Tx antenna
Orthogonal preamble by using subcarriers alternatively
Heejung Yu, ETRI

20. August 2004
SIGNAL bit assignment
802.11n device uses the R4 to distinguish the legacy and multi-antenna
R4 = 1 : legacy OFDM
R4 = 0 : multi-antenna (STBC-OFDM, SDM-OFDM)
802.11n device uses the reserved bit to distinguish STBC-OFDM and SDM-OFDM.
For legacy device, discard
For Alamouti code, A = 0
For SDM, A = 1
Heejung Yu, ETRI

21. RATE and ANTENNA field definition Rate-dependant parameters
August 2004
RATE and ANTENNA field definition Rate-dependant parameters
{R1-R4, A}
Data rate
Modulation
Coding rate
NBPSC
NCBPS
NDBPS
Antenna mode
1101x 6
BPSK
12 1 48 24
Legacy OFDM
1111x 9
34 36
0101x 12
QPSK 2 96
0111x 18 72
1001x
16-QAM 4
192
1011x
144
0001x
64-QAM
2/3
288
0011x 54
216
Heejung Yu, ETRI

22. RATE and ANTENNA field definition Rate-dependant parameters
August 2004
RATE and ANTENNA field definition Rate-dependant parameters
{R1-R4, A}
Data rate
Modulation
Coding rate
NBPSC
NCBPS
NDBPS
Antenna mode
11000 6
BPSK
12 1 48 24
STBC-OFDM
11100 9
34 36
01000 12
QPSK 2 96
01100 18 72
10000
16-QAM 4
192
10100
144
00000
64-QAM
2/3
288
00100 54
216
Heejung Yu, ETRI

23. RATE and ANTENNA field definition Rate-dependant parameters
August 2004
RATE and ANTENNA field definition Rate-dependant parameters
{R1-R4, A}
Data rate
Modulation
Coding rate
NBPSC
NCBPS
NDBPS
Antenna mode
10101 72
16-QAM
34 8
384
288
SDM-OFDM
00001 96
64-QAM
2/3 12
576
00101
108
432
11001
128
256-QAM 16
768
512
01001
144
These parameters are based on single band.
NBPSC : Coded bits per subcarrier
NCBPS : Coded bits per OFDM symbol
NDBPS : Data bits per OFDM symbol
Heejung Yu, ETRI

24. SIGNAL Field Modulation
August 2004
SIGNAL Field Modulation
Single Antenna single band (same as a)
Subcarrier allocation :
Dual antenna single band
Single antenna dual band
Dual antenna dual band
Heejung Yu, ETRI

25. DATA Field (changed parts) Pad bits, Data arbitrator
August 2004
DATA Field (changed parts) Pad bits, Data arbitrator
Pad bits
To make DATA bits to be an integer multiple of NDBPS (Legacy OFDM, SDM-OFDM), or 2NDBPS(STBC-OFDM).
Data arbitrator
Receive one byte from MAC,
even numbered 4 bits directed to scrambler(channel) 0 and odd numbered 4 bits to scrambler(channel) 1.
Heejung Yu, ETRI

26. DATA Field (changed parts) Interleaving
August 2004
DATA Field (changed parts) Interleaving
Interleaver : block interleaver
Interleaver size : NCBPS(single band), 2NCBPS(dual band)
Interleaver (Single band. In dual band, all NCBPS’s are replaced with 2NCBPS)
Deinterleaver (Single band. In dual band, all NCBPS’s are replaced with 2NCBPS)
Heejung Yu, ETRI

27. DATA Field (changed parts) Modulation mapping
August 2004
DATA Field (changed parts) Modulation mapping
Optional 256-QAM is added to a modulations
Kmod =
Heejung Yu, ETRI

28. DATA Field (changed parts) Antenna arbitration
August 2004
DATA Field (changed parts) Antenna arbitration
Legacy OFDM
Single band case
Dual band case
Heejung Yu, ETRI

29. DATA Field (changed parts) Antenna arbitration
August 2004
DATA Field (changed parts) Antenna arbitration
STBC-OFDM
Single band case
Ant 0
Ant 1
Dual band case
Ant Ant1
Heejung Yu, ETRI

30. DATA Field (changed parts) Antenna arbitration
August 2004
DATA Field (changed parts) Antenna arbitration
SDM-OFDM
Single band case
Ant 0
Dual band case
Ant 1
Heejung Yu, ETRI

31. DATA Field (changed parts) OFDM Modulation
August 2004
DATA Field (changed parts) OFDM Modulation
OFDM modulation for i-th antenna j-th channel
One OFDM symbol modulation
Concatenation of multiple OFDM symbols
OFDM modulation for dual band
Heejung Yu, ETRI

32. Transmitter structure
August 2004
Transmitter structure
Using one 128 (I)FFT structure
Heejung Yu, ETRI

33. Transmitter structure
August 2004
Transmitter structure
Modified structure with 64 point FFT
Heejung Yu, ETRI

34. August 2004
Transmit spectrum
Tx spectrum for dual band is the extended version of legacy 11a spectrum
Heejung Yu, ETRI

35. August 2004
Simulation Results
Heejung Yu, ETRI

36. August 2004
Detection Method
In Legacy OFDM, Maximal Ratio Combining method is used.
In SDM-OFDM, Zero Forcing scheme is used.
The simplest and reasonable method considering both implementation complexity and performance
In higher order modulation and smaller number of Nt case, SNR loss between ZF and ML (Maximum Likelihood) becomes lower.
Heejung Yu, ETRI

37. AWGN performance 1 Tx, 1 Rx antenna (only for Legacy mode) August 2004
Heejung Yu, ETRI

38. August 2004
AWGN performance
2 Tx, 2 Rx antennas
Heejung Yu, ETRI

39. August 2004
AWGN performance
2 (out of 3) Tx, 3 Rx antennas (We select 2 antennas out of 3 Tx antennas.)
Heejung Yu, ETRI

40. August 2004
AWGN performance
2 (out of 4) Tx, 4 Rx antennas (We select 2 antennas out of 4 Tx antennas.)
In AWGN channel,
Nr  => detection SNR 
(no diversity gain)
=> (Nr = 4) has 3dB gain over (Nr = 2).
Nt , SNR per info. bit 
(to normalize total Tx power)
=> 54Mbps has 3dB gain over 108Mbps.
Heejung Yu, ETRI

41. Non-AWGN performance 2 Tx and 3 Rx antennas are used.
August 2004
Non-AWGN performance
2 Tx and 3 Rx antennas are used.
In Legacy mode, randomly selected single Tx antenna is used.
Antenna spacing
Tx spacing : 1 wavelength (2 out of 3 antennas are used.)
Rx spacing : ½ wavelength (3 antennas)
Power amplifier backoff : 10dB (p=3 RAPP mode)
CFO and timing offset : ppm
Channel model : B, D (with fluorescent effect), and E (NLOS)
Packet size : 1000 bytes
Heejung Yu, ETRI

42. Non-AWGN performance Channel model B (NLOS) August 2004
Heejung Yu, ETRI

43. Non-AWGN performance Channel Model D (NLOS) August 2004
Heejung Yu, ETRI

44. Non-AWGN performance Channel model E (NLOS) August 2004
Heejung Yu, ETRI

45. Offset effect Channel E (NLOS) Solid : offset compensation performance
August 2004
Offset effect
Channel E (NLOS)
Solid : offset compensation performance
Dash : zero offset performance
CFO and timing tracking loop coefficients are optimized for high data rates.
Heejung Yu, ETRI

46. Offset effect Channel E (LOS), at 50dB SNR
August 2004
Offset effect
Channel E (LOS), at 50dB SNR
Constellation of 108Mbps mode with different offset values
40ppm
20ppm
-20ppm
-40ppm
Heejung Yu, ETRI

47. Offset effect Channel E (LOS), at 50dB SNR
August 2004
Offset effect
Channel E (LOS), at 50dB SNR
Constellation of 6Mbps mode with different offset values
40ppm
10ppm
-10ppm
-40ppm
Heejung Yu, ETRI

48. August 2004
Conclusions
Heejung Yu, ETRI

49. August 2004
Conclusions
In this proposal, MIMO-OFDM with 2 transmit antennas and dual band scheme are used for higher data rate (throughput).
SDM-OFDM : double data rate
Dual band : double data rate
STBC-OFDM : increase link reliability (optional)
To satisfy the FR (100Mbps throughput in 20MBz), 256-QAM is added (144Mbps in 20MHz band)
Compatible with a (Preamble and SINGAL structure)
Heejung Yu, ETRI

50. August 2004
Appendix
Heejung Yu, ETRI

51. August 2004
A1. Dual-band
Subcarriers of 128 points FFT are divided into two 64 subcarriers corresponding to 64 FFT in a/g.
64 subcarriers
40MHz
11 “0” carriers
Heejung Yu, ETRI

52. A2. Preamble Pattern (Dual Antenna Single Band)
August 2004
A2. Preamble Pattern (Dual Antenna Single Band)
Short preamble
(Ant 0 : even subcarriers, Ant 1 : odd subcarriers)
Long preamble
Heejung Yu, ETRI

53. A2. Preamble Pattern (Single Antenna Dual Band)
August 2004
A2. Preamble Pattern (Single Antenna Dual Band)
Short preamble (concatenation of single band preambles)
Long preamble (concatenation of single band preambles)
Heejung Yu, ETRI

54. A2. Preamble Pattern (Dual Antenna Dual Band)
August 2004
A2. Preamble Pattern (Dual Antenna Dual Band)
Short preamble (concatenation of single band preambles)
Long preamble (concatenation of single band preambles)
Heejung Yu, ETRI