1. Towards IEEE802.11 HDR in the Enterprise
May 2002
Towards IEEE HDR in the Enterprise
Sebastien Simoens, Amitava Ghosh, Alistair Buttar, Karine Gosse, Ken Stewart
Motorola
Contact:

2. Future Enterprise Enterprise data needs will continue to grow
May 2002
Future Enterprise
Enterprise data needs will continue to grow
Ethernet LANs will use 1Gb/s and 10Gb/s technologies in 2005
Deployment of WLAN APs will complement wireline and cellular infrastructure
Peak data rate of >100Mb/s is attractive to IT departments (alternative to 100Base-T)
Higher peak data rates and higher average throughput result in productivity enhancements in the enterprise
Market trends support HDR standardization effort

3. HDR Requirements Extend 802.11a in the 5GHz band
May 2002
HDR Requirements
Extend a in the 5GHz band
Peak data rate >100Mb/s, and increased cell throughput
Broad regulatory support
Graceful degradation as the system load increases
Backwards compatible with
Support for limited mobility
Optimized PHY/MAC solution
More efficient MAC enables to take advantage of higher rate PHY (see « WNG requirements for Home networking »)

4. Technology Considerations
May 2002
Technology Considerations
Advanced channel coder, e.g. Turbo Codes or Turbo Trellis Coded Modulation
OFDM but with higher order QAM (e.g. 256) and higher number of sub-carriers
Hybrid ARQ
Spatial Diversity Techniques e.g. 2x2 MIMO
Link Adaptation (already supported)
Reduced Overhead / Improved Signalling
Efficient QoS support
Improved performance can also be traded-off for lower power consumption, or increased robustness

5. Improved Channel Coder
May 2002
Improved Channel Coder
Use low constraint length Turbo Code eg. (K=3) R=1/3 instead of current K=7 R=1/2 convolutional code
Limit the number of iterations to 4 to reduce complexity at the terminal
1-3dB gain can be achieved with Turbo codes compared to convolutional code

6. May 2002
Hybrid ARQ
Self-optimizing and adjusts automatically to channel conditions
Adds redundancy only when needed
Receiver saves failed transmission attempts to help future decoding
Every transmission helps to increase the packet success probability
HARQ Scheme should support both Incremental Redundancy (IR) and Chase Combining
Enabled by N-Channel Stop-and-Wait ARQ
AT-assisted Channel Quality Indication (CQI)
Channel reciprocity needs to be considered here, although potential differences in UL/DL interference levels.
Key Challenges
Can be best accommodated using optimized MAC
Memory cost at the terminal needs to be optimized

7. 2x2 Spatial Diversity (1/3)
May 2002
2x2 Spatial Diversity (1/3)
2 Transmit, 2 Receive antenna system
Already addressed in other standards ( , 3GPP)
Improves peak data rate and/or average data throughput
Reasonable additional complexity
Many alternatives to exploit the 2x2 configuration:
link budget/cell throughput improvement relying on spatial diversity: Tx space-time block coding, Rx diversity
bit-rate increase with parallel data flows: Multiple Input Multiple Output techniques (MIMO) can be considered
« Beamforming » with channel knowledge at Tx: most gain obtained but requires feedback channel or TDD channel reciprocity assumption
Need for comparisons in terms of overall cell throughput
Need for defining the level of acceptable complexity at AP and MT

8. 2x2 Spatial diversity (2/3)
May 2002
2x2 Spatial diversity (2/3)
QPSK, 16QAM
rate ½ code
Packets: 2x54 bytes
Space-Time Block Coding on .11a PHY, office NLOS channel
2x2
8.7dB
1x1
2x2 shows a significant improvement of 8.7dB at PER=10-2

9. 2x2 Spatial diversity (3/3)
May 2002
2x2 Spatial diversity (3/3)
10.5Mb/s
A significant cell range extension can be obtained
18Mb/s
29m
Based on previous slide PHY results,
with path loss (n=3.8) and shadowing

10. May 2002
Conclusion
Goal of HDR is to improve peak as well as the average throughput
Technology elements exist for efficient HDR WLAN
Standardization activity should be started before proprietary products fragment the marketplace
HDR Study Group should be created in