The IEEE802.11n standard will enable a new class of consumer and enterprise products utilizing wireless LAN connectivity that is ten times faster than is feasible with the current IEEE802.11a/b/g standards. This tutorial will provide a comprehensive overview of the technology in the p802.11n draft standard.
We begin with an overview of the applications, environments, channel models, use cases, and usage models developed by the study group and task group which provided the framework for proposal development. We continue with a history of the various coalitions that ultimately led to the final joint proposal adopted as the draft standard.
The technical description of the draft standard starts with a detailed discussion of the key throughput enhancing features: multiple-input, multiple-output (MIMO) / space division multiplexing (SDM) in the PHY and packet aggregation in the MAC. Further throughput enhancements in the PHY include 40 MHz channelization, reduced guard interval, tone filling, high rate coding, and efficient (greenfield) preambles. In the MAC this includes enhancements to the block acknowledgement (BA) protocol, such as a compressed BA frame format, implicit BA request, partial state operation, and no ACK delayed BA protocol. The reverse direction data protocol, which provides throughput enhancements for certain types of traffic patterns, is also discussed.
Additional topics include PHY interoperability techniques such as the mixed mode preamble, legacy spoofing, auto-preamble detection, and MAC techniques such as long network allocation vector (NAV) protection, legacy signal field (L-SIG) transmit opportunity (TXOP) protection, greenfield and reduced inter-frame space (RIFS) operation, 20/40MHz phase coexistence operation, and channel width management.
An overview will be provided of the robustness enhancements in both the MAC and the PHY. The PHY techniques include spatial spreading, receive diversity, transmit beamforming, space-time block code (STBC), and low density parity check (LDPC) codes. The MAC techniques include fast link adaptation and beamforming control.
Finally, we highlight video streaming as the key application that benefits from the IEEE802.11n standard. An overview of the throughput, latency, and reliability requirements for video is provided. This is followed by a review of how the robustness and throughput enhancements meet these requirements and significantly improve video streaming performance over what is achievable on WLANs today.
Biographies:
Dr. Eldad Perahia
Dr. Eldad Perahia leads Intel Corporation’s Standards and Advanced Architecture and Development team. He has been actively involved in the 802.11 high throughput task group since its inception. Prior to Intel, Eldad was the 802.11n lead for Cisco Corporation. He has thirteen patents, and numerous papers and patent filings in various areas of wireless including satellite communications, cellular, WLAN, millimeter wave technology, and radar. Eldad has a Ph.D. from the University of California, Los Angeles in electrical engineering specializing in digital radio.
Mr. Robert Stacey
Robert Stacey manages Intel Corporation’s Wireless MAC Advanced Development team. He is a member of the 802.11 high throughput task group and was a key contributor to the various proposals culminating in the final joint proposal submission that became the basis for the 802.11n draft standard. Robert has numerous patents filed in the field of wireless communications. Robert has a MSEE from University of the Witwatersrand, South Africa. |
