IEEE WirelessMAN For Broadband Wireless Metropolitan Area Networks

IEEE 802 The LAN/MAN Standards Committee Wired: –802.3 (Ethernet) – (Resilient Packet Ring) Wireless: –802.11: Wireless LAN Local Area Networks –802.15: Wireless PAN Personal Area Networks {inc. Bluetooth} –802.16: WirelessMAN TM Metropolitan Area Networks –802.20: Vehicular Mobility (new)

IEEE Projects Air Interface (PHYs with common MAC) –802.16: GHz –802.16a: 2-11 GHz Coexistence –IEEE (10-66 GHz) –P a: amendment with 2-11 GHz licensed

Properties of IEEE Standard Broad bandwidth –Up to 134 Mbit/s in 28 MHz channel (in GHz air interface) Supports multiple services simultaneously with full QoS –Efficiently transport IPv4, IPv6, ATM, Ethernet, etc. Bandwidth on demand (frame by frame) MAC designed for efficient used of spectrum Comprehensive, modern, and extensible security Supports multiple frequency allocations from 2-66 GHz –ODFM and OFDMA for non-line-of-sight applications TDD and FDD Link adaptation: Adaptive modulation and coding –Subscriber by subscriber, burst by burst, uplink and downlink Point-to-multipoint topology, with mesh extensions Support for adaptive antennas and space-time coding Extensions to mobility are coming next.

Point-to-Multipoint Wireless MAN: not a LAN Base Station (BS) connected to public networks BS serves Subscriber Stations (SSs) –SS typically serves a building (business or residence) –provide SS with first-mile access to public networks Compared to a Wireless LAN: –Multimedia QoS, not only contention-based –Many more users –Much higher data rates –Much longer distances

Scope of 802 Standards

PHY Considerations Line of Sight (because of GHz) –Negligible multi-path Broadband Channels –Wide channels (20, 25, or 28 MHz) –High capacity – Downlink AND Uplink Multiple Access –TDM/TDMA –High rate burst modems Adaptive Burst Profiles on Uplink and Downlink Multiple duplex schemes –Time-Division Duplex (TDD) –Frequency-Division Duplex (FDD) [including Burst FDD] Support for Half-Duplex Terminals

Adaptive Burst Profiles Burst profile –Include transmission parameters such as modulation and FEC Dynamically assigned according to link conditions –Burst by burst, per subscriber station –Trade-off capacity vs. robustness in real time Roughly doubled capacity for the same cell area Burst profile for downlink broadcast channel is well- known and robust –Other burst profiles can be configured “on the fly” –SS capabilities recognized at registration

Framing Structure Frame length: 0.5, 1, or 2 ms Allocation process is done in terms of PSs –PS = Physical Slot = 4 Modulation Symbols –Depending on modulation, a PS contains 1, 2, or 3 bytes

DL-MAP specifies when physical layer transitions (modulation and FEC) occur within the downlink subframe UL-MAP specifies bandwidth allocations And burst profiles on the uplink

UL-MAP within the frame control grants bandwidth and burst profiles to specific SSs. Initial ranging for transmit time advance and power adjustments

MAC Requirements Provide Network Access Address the Wireless environment –e.g., very efficient use of spectrum Broadband services –Very high bit rates, downlink and uplink –A range of QoS requirements –Ethernet, IPv4, IPv6, ATM,... Likelihood of terminal being shared –Base Station may be heavily loaded Security Protocol-Independent Engine –Convergence layers to ATM, IP, Ethernet,... Support PHY alternatives –Adaptive mod, TDD/FDD; single-carrier, OFDM/OFDMA, etc

MAC: Overview Point-to-Multipoint Metropolitan Area Network Connection-oriented Supports difficult user environments –High bandwidth, hundreds of users per channel –Continuous and burst traffic –Very efficient use of spectrum Protocol-Independent core (ATM, IP, Ethernet, …) Balances between stability of contentionless and efficiency of contention-based operation Flexible QoS offerings –CBR, rt -VBR, nrt-VBR, BE, with granularity within classes Supports multiple PHYs

Definitions Service Data Unit (SDU) –Data units exchanged between adjacent layers Protocol Data Unit (PDU) –Data units exchanged between peer entities Connection and Connection ID –a unidirectional mapping between MAC peers over the airlink (uniquely identified by a CID) Service Flow and Service Flow ID –a unidirectional flow of MAC PDUs on a connection that provides a particular QoS (uniquely identified by a SFID)

MAC Addressing SS has 48-bit IEEE MAC Address BS has 48-bit Base Station ID –Not a MAC address –24-bit operator indicator 16-bit Connection ID (CID) –Used in MAC PDUs

Possible Consideration QoS –In GPC, if the amount of the connections are very high, then SS should not request BW for each connection, which is resource consuming. –In GPSS, SS should aggregate all the connections that are with different services, and request BW from BS. Scheduling problem? Mesh topology support