(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property Organization
`
`(43) International Publication Date
`14 February 2002 (14.02.2002)
`
`International Bureau
`
`I
`PCT
`
`(10) international Publication Number
`wo 02/13429 A1
`
`(S1) InternationalPatent Classificationl:
`H04Q 7/28
`
`H04J 3/00,
`
`(21) International Application Number:
`
`PCT/US01/21796
`
`(22) International Filing Date:
`
`11 July 2001 (11.07.2001)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`English
`
`English
`
`(30) Priority Data:
`60/223,993
`60/230,412
`
`9 August 2000 (09.08.2000)
`6 September 2000 (06.09.2000)
`
`US
`US
`
`(71) Applicant (for all designated States except US): HLAN
`INC. [US/IL]; Merkaz Sharona, 12.DerechHasha1on, Kfar
`Saba 44269 (IL).
`
`(72) Inventors; and
`(75) Inventors/Applicants (for US only): TEXERMAN,Yossi
`[IL/IL]; 7 Yaakov Dori St., Modiin 71700 (IL). DAVIDI,
`
`Oren [IL/IL]; 17 Ilaeshel St., Ramat Gan 52535 (IL).
`HALPERIN, Arik [IL/IL]; 14 Harzit St., Modiin 71700
`(IL)-
`
`(74) Agent: FRIEDMAN, Mark, M.; c/o Castorina, Anthony,
`2001 Jefferson Davis Highway, Suite 207, Arlington, VA
`22202 (US).
`
`(81) Designated States (national): AE, AG, AL, AM, AT, AU,
`AZ, BA, BB, BG, BR, BY, BZ, CA, CH, CN, CO, CR, CU,
`CZ, DE, DK, DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM,
`HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK,
`LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX,
`MZ, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL,
`TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW.
`
`(84) Designated States (regional): ARIPO patent (GH, GM,
`KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZW), Eurasian
`patent (AM, AZ, BY, KG, KZ, MD, RU, T.I, TM), European
`patent (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE,
`IT, LU, MC, NL, PT, SE, TR), OAPI patent (BF, BJ, CF,
`CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG).
`
`[Continued on next page]
`
`(54) Title: COMMUNICATIONS PROTOCOL FOR WIRELESS LAN HARMONIZING THE IEEE 802.11a AND ETSI HiPer—
`LAN/2 STANDARDS
`
`faaoo
`
`Multimedia Environment
`
`Ethernet Environment
`
`Multimedia
`
`Access Point
`
`Ethernet
`Access Point
`
`/13429A1
`
`(57) Abstract: A unified communications protocol for wireless local area networks (WLANS) (400) which provides for the fair
`co—existence of the
`802.11a ("1 la") and I-IiPerl.AN/2 ("I-II.2"), broadband communications standards. Wireless network de-
`vices (MTS) operating in accordance with 1 la and HL2 may co—exist without interference by partitioning a 2 ms periodic time domain,
`3] based on the HL2 standard, into a first slice for use by 11a MTs and a slice for use by HL2 devices. An Arbitrator entity (ARB)
`broadcasts the time slices periodically at an interval which is greater than or equal to the periodic time domain. A first access Point
`(E—AP) handles communication with the E—MTs, and a second Access Point (M—AP) handles communications with the e—MTSs and
`the M—MTs. In this manner, convergence is provided between 11a and HL2, providing users with the best of both worlds, e.g., full
`interoperability, QoS and co—eXistence.
`
`1
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`APPLE 1012
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`APPLE 1012
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`||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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`Published:
`— with international search report
`
`For two-letter codes and other abbreviations, refer to the "Guid-
`ance Notes on Codes and Abbreviations" appearing at the begin-
`ning ofeach regular issue ofthe PCT Gazette.
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`COMMUNICATIONS PROTOCOL FOR WIRELESS LAN
`
`HARMONIZING THE IEEE 802.1 la AND ETSI HiPerLAN/2 STANDARDS
`
`TECHNICAL FIELD OF THE INVENTION
`
`The invention relates to wireless communications and, more particularly, to a
`
`communications protocol
`
`(standard)
`
`for wireless local area network (WLAN)
`
`applications,
`
`taking into account
`
`the IEEE 802.1la standard and the ETSI
`
`HiPerLAN/2 standard.
`
`BACKGROUND OF THE INVENTION
`
`A local area network (LAN) is a network of independent computers, usually
`
`confined to a geographic area, such as a single building or a college campus. LANS
`
`can be small, linking as few as three computers, but often link hundreds of computers
`
`used by‘ thousands of people. The development of standard networking protocols and
`
`media has resulted in Worldwide proliferation of LANS throughout business and
`
`educational organizations.
`
`Ethernet is the most popular physical layer LAN technology in use today. The
`
`Institute for Electrical and Electronic Engineers (IEEE) defines the Ethernet standard
`
`as IEEE Standard 802.3. This standard defines rules for configuring an Ethernet
`
`network as well as specifying how elements in an Ethemet network interact with one
`
`another. By adhering to the IEEE standard, network equipment and network protocols
`
`can communicate efficiently.
`
`Ethernet uses Collision Sense Multiple Access with Collision Detection
`
`(CSMA/CD). When an Ethernet station is ready to transmit, it checks for the presence
`
`of a signal on the cable. If no signal is present then the station begins transmission,
`
`however if a signal is already present then the station delays transmission until the
`
`cable is not in use. If two stations detect an idle cable and at the same time transmit
`
`data, then a collision occurs. The two stations involved with the collision lay off
`
`transmitting again for a time interval which is randomly selected.
`
`If the collision
`
`occurs again, then the time interval is doubled, and if the collision happens repeatedly,
`
`an error is reported.
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`The 'Ether' part of Ethernet denotes that the system is not meant to be restricted for
`
`use on only one medium type. Copper cables, fibre cables and radio waves can be used.
`
`A wireless LAN (WLAN) is a data transmission system designed to provide
`
`location-independent network access between computing devices by using radio waves rather
`
`than a cable infrastructure. The major motivation and benefit from WLANS is increased
`
`mobility. Untethered from conventional network connections, network users can move about
`
`almost Without restriction and access LANs from nearly anywhere. Wireless LANS also offer
`
`the connectivity and the convenience of wired LANs without the need for expensive wiring
`
`or rewiring.
`The 5 GigaHertz (GHz) band is of particular interest for high bandwidth WLAN
`
`10
`
`products. Being spectrally clean and wide, the 5 GHz band attracts much attention as being
`
`the enabler of wide public acceptance for broadband WLAN products.
`
`In the US, the 5 GHz,
`
`U-NII (Unlicensed National Information Infrastructure) band extends from 5.15 GHz to
`
`5.825 GHz, and is divided into three parts (bands) with different allowed EIRP (Effective
`
`Isotropically Radiated Power) values. The 200 mW band provides for in-building operation.
`
`The 1 W band allows campus or small neighborhood services. The 4W band allows for
`
`services of up to approximately 10 km.
`
`The 5 GHz band is open in Europe, the United
`
`States and Japan. The current spectrum allocation at 5 GHz comprises 455 MHZ in Europe,
`
`300 MHZ in the US, and 100 MHZ in Japan.
`
`Two WLAN standards (protocols) for the 5GHz band have emerged, the IEEE
`
`802.1 la (hereinafter referred to as "8021 1" or "l la") and HiPerLAN/2 (hereinafier referred
`to as "HL2"). A common viewiin the industry is that these two standards are in competition
`
`with one another. Whereas the Ethernet-based 1 la standard is particularly well-suited to the
`
`15
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`20
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`business environment, the multimedia—based HL2 standard is particularly well-suited to the
`
`25
`
`home environment. As the industry has learned fiom past experience, competing standards
`
`and uncertainties about standard adoption and interoperability issues can greatly adversely
`
`the proliferation of products.
`
`30
`
`Each of the 11a and HL2 standards utilizes its own definitions and abbreviations. It is
`
`Protocol-Specific Definitions & Abbreviations
`
`therefore useful, for purposes of this document, to establish a common terminology, as
`
`follows :
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`Ethernet elements
`
`lla elements may be referred to as Ethernet elements.
`
`Multimedia elements
`
`HL2 elements may be referred to as Multimedia elements.
`
`Co-existence
`
`The ability of two wireless elements, each consistent with a
`different protocol both at
`the same frequency,
`to Work
`adjacently without interference.
`
`Partial Interoperability
`
`The ability of two wireless elements, each consistent with a
`different protocol,
`to exchange information through a third
`element.
`
`Full Interoperability
`
`The ability of two wireless elements, each consistent with a
`different protocol, to exchange information directly.
`
`Access Point
`
`This term is used to describe a so-called “base station” in both
`
`the 11a and HL2 standard(s). With reference to the present
`invention, the following prefixes will be used.
`Ethemet Access Point (consistent with the 1 la term — AP/PC)
`Multimedia Access Point (consistent with the HL2 tenn — AP/CC)
`Unified Access Point (a "coined" term)
`
`E—AP
`M-AP
`U—AP
`
`Mobile Terminal
`
`This term is used to describe all wireless network elements
`
`except the Access Point, including stationary terminals, in both
`the 1 la and HL2 standard(s). With reference to the present
`invention, the following prefixes will be used.
`Ethernet Mobile Terminal (consistent with the 1 la term - STA)
`Multimedia Mobile Terminal (consistent the HL2 term — MT)
`Unified Mobile Terminal (a "coined" term)
`
`E-MT
`M-MT
`U—MT
`
`IEEE 802.I1a ("Ila")
`
`The IEEE 802.11 ("Ila") standard is a broadband communication standard for
`
`WLANs, and defines two pieces of equipment, a wireless station (STA, herein "MT"), which
`
`is usually a personal computer (PC) equipped with a wireless network interface card (NIC),
`
`and an access point (AP), which acts as a bridge between the wireless and wired networks.
`
`An AP usually consists of a radio, a Wired network interface (e.g., Ethernet), and bridging
`
`software conforming to the IEEE 802.ld bridging standard. The AP acts as the base station
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`35
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`for the wireless network, aggregating access for multiple MTs onto the wired network.
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`40
`
`Wireless stations can be 802.11 PC Card, PCI, or ISA NICs, or embedded solutions in
`
`non-PC clients (such as an 802.11-based telephone handset).
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`The 11a standard defines two modes of operation - an infrastructure mode and an
`
`ad-hoc mode.
`
`In the infrastructure mode, the wireless network consists of at least one AP
`
`connected to the wired network infrastructure and a set of MTs. This configuration is called
`
`a Basic Service Set (BSS). An Extended Service Set (ESS) is a set of two or more BSSS
`
`forming a single subnetwork. Since most corporate wireless LANs require access to the wired
`
`LAN for services (file servers, printers, Internet links) they typically operate in infrastructure
`
`mode. The ad-hoc mode (also called peer-to-peer mode, or Independent Basic Service Set,
`IBS) is simply a set of wireless stations (MTs) that communicate directly with one another
`
`without using an AP or any connection to a wired network. ‘ This mode is useful for quickly
`and easily‘ setting up a wireless network anywhere that a wireless infrastructure does not exist
`
`10
`
`or is not required for services, such as in a hotel room, convention center, or airport, or
`where access to the wired network is barred (such as for consultants at a client site).
`
`The lla standard includes both a physical (PHY) layer and a medium access control
`
`(MAC) layer of the network. Generally, the PHY layer handles the transmission of data
`
`between nodes, and the MAC layer is a set of protocols which is responsible for maintaining
`
`order in the use of a shared medium.
`
`The 1 la MAC layer is responsible-for how a wireless station (MT) associates with an
`
`access point (AP). When an MT enters the range of one or more APs, it chooses an AP to
`
`associate with (also called "joining the Basic Service Set"), based on signal strength and
`
`observed packet error rates. Once accepted by the AP, the MT tunes to the radio channel to
`
`which the AP is set. Periodically, the MT surveys all of the available channels in order to
`
`assess whether a different AP would provide it with better performance characteristics. If it
`
`detennines that this is the case, the MT reassociates with the new AP, tlming to the radio
`
`channel to which that AP is set. Reassociation usually occurs because the MT has physically
`
`moved away from the original AP, causing the signal to weaken. In other cases, reassociation
`
`occurs due to a change in radio characteristics in the building, or due simply to high network
`
`traffic on the original access point. In the latter case this function is known as “load
`
`balancing,” since its primary function is to distribute the total WLAN load most efficiently
`
`across the available wireless infrastructure.
`
`A MAC-layer problem specific to wireless LAN is the “hidden node” issue, in which
`
`two stations on opposite sides of an AP can both “hear” activity from the AP, but not from
`
`each other, usually due to distance or an obstruction. To address this issue, the 11a standard
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`specifies an optional Request to Send/Clear to Send (RTS/CTS) protocol at the MAC layer.
`
`When this feature is in use, a sending station (MT) transmits an RTS and waits for the access
`
`point to reply with a CTS. Since all stations in the BSS can hear the access point, the CTS
`
`causes them to delay any intended transmissions, allowing the sending station to transmit and
`
`receive a packet acknowledgment without any chance of collision.
`
`Hz:perLAN/2 (HL2)
`
`HL2 is a another wireless LAN standard which includes both a Physical (PHY) Layer
`
`and a Medium Access Control (MAC) layer, and other layers as described hereinbelow. HL2
`
`_l0
`
`provides high—speed communications with a bit rate of up to 54-Mbits/s between Mobile
`
`Terminals (MTS) and various broadband infrastructure networks. The HL2 standard relies on
`cellular networking topology combined with an ad—hoc networking capability. It supports two
`
`basic modes of operation: centralized mode and direct mode. The centralized mode is used in
`
`the cellular networking topology where each radio cell is controlled by an access point (AP)
`
`covering a certain geographical area.
`
`In this mode, a mobile terminal (MT) communicates
`
`with other mobile terminals (MTS) or with the core network via an AP. This mode of
`
`operation is mainly used in business applications, both indoors and outdoors, where an area
`
`much larger than a radio cell has to be covered. The direct mode is used in the ad—hoc
`
`networking topology, mainly in typical private home environments, where a radio cell covers
`
`the whole serving area. In this mode, mobile terminals (MTS) in a single-cell home "network"
`
`can directly exchange data.
`The PHY layer maps MAC Protocol Data Units (PDUs) to PHY PDUS, and adds
`
`PHY signaling such as
`
`system parameters
`
`and headers
`
`intended for RF signal
`
`synchronization. The signal modulation is based on Orthogonal Frequency Division
`
`Multiplexing (OFDM) with several sub-carrier modulation and forward error correction
`
`combinations that allow to cope with various charmel configurations.
`
`An intermediate layer, the Channel Access and Control (CAC) sub-layer, deals with
`
`channel access signaling and protocol operation required to support packet priority. A
`
`pseudo-hierarchically independent access mechanism is achieved via active signaling in a
`
`listen-before-talk access protocol. This mechanism (Elimination-Yield Non-Preemptive
`
`Multiple Access, EY-NPMA) codes priority level selection and contention resolution into a
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`single, variable length radio pulse preceding packet data. EY-NPMA provides good residual
`
`collision rate performance for even large numbers of simultaneous channel contenders.
`
`The HL2 standard also includes a Data Link Control (DLC) layer. Two specifications
`
`address the basic part of the DLC layer. The first one includes the basic data transport
`
`functions consisting of Error Control protocol and Medium Access Control (MAC) protocol.
`
`The second specification defines the Radio Link Control (RLC) Sublayer that is used for
`
`exchanging data in the control plane between an access point (AP) and a mobile terminal
`
`(MT). Furthermore, two specifications are developed for Home and Business profiles of the
`
`DLC. The air interface of HL2 is based on Time Division Duplex (TDD) and dynamic Time
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`10
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`Division Multiplex (TDMA).
`
`The HL2 standard also specifies Convergence Layers (CLS). A CL has two main
`
`functions: Adapting service requests from higher layers to the services offered by the DLC
`
`and converting the higher layer packets with fixed or variable size into fixed-size DLC
`
`Service Data Units that is used within the DLC. Convergence layers have been developed for
`
`Ethernet (IP based) applications, cell based core networks as ATM and for IEEE1394
`
`protocols and applications.
`
`The HL2 standard defines a set of protocols (measurements and signaling) to provide
`
`support for a number of radio network functions, e.g. Dynamic Frequency Selection (DFS),
`
`link adaptation, handover, multi beam antennas and power control, where the algorithms are
`
`vendor specific. The supported radio network functions allow cellular deployment of HL2
`
`systems with full coverage and high data rates in a wide range of environments. The system
`
`automatically allocates frequencies to each access point for communications. This is
`
`performed by the DFS, which allows several operators to share the available spectrum by
`
`avoiding the use of interfered frequencies.
`
`Performance is one of the most important factors when dealing with wireless LANS.
`
`In contrast to other radio—based systems, data traffic on a LAN has a randomized bursty
`
`nature, which may cause serious problems with respect to throughput. Many factors have to
`
`be taken into consideration, when quality of service (QOS) is to be measured. Among these
`
`are the topography of the landscape in general, elevations in the landscape that might cause
`
`shadows where
`
`connectivity is unstable or
`
`impossible,
`
`environments with many
`
`signal—reflection surfaces, environments with many signal-absorbing surfaces, quality of the
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`wireless equipment, placement of the wireless equipment, number of stations, proximity to
`
`installations that generate electronic noise, and many more.
`
`To cope with the varying radio link quality (interference and propagation conditions),
`
`the HL2 standard uses a link adaptation (LA) scheme, the aim of which is keeping up
`
`communications link at low signal-to-interference ratios in order to maintain the QoS, and to
`
`trade off between communications range and data rate. Based on link quality measurements,
`
`the physical layer data rate is adapted to the current link quality. Transmitter power control is
`
`supported in both mobile terminal (uplink) and access point (downlink). The uplink power
`
`control is mainly used to simplify the design of the access point receiver by avoiding
`
`automatic gain control at access point. The main goal of downlink power control is to fulfill
`
`the regulatory requirements in Europe to decrease interference to other systems using the
`
`same 5 GHZ band.
`A typical ‘HL2 MAC Frame is of 2 ms duration, and comprises the following
`
`functions/phases:
`
`BCH
`FCH
`ACH
`DL
`DIL
`
`UL
`RCH
`
`Broadcast CHannel
`Frame CHaImel
`Access feedback CHannel
`Downlink
`Direct Link
`
`Uplink
`Random Channel(s)
`
`Frequency Sharing Rules (FSRS)
`
`Both of the lla and HL2 standards have chosen the same OFDM—based approach in
`
`the PHY layer. Therefore, harmonization of the PHY layer is relatively straightforward, and
`needs no further discussion. On the other hand,
`the 11a and HL2 standards have
`
`implemented very different solutions in the MAC layer. While the lla standard CSMA/CA
`
`MAC is optimized for wireless data communication, providing simple and field proven
`
`solution for wireless Ethernet and IP, the HL2 standard, with its build-in support for quality
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`of service (Q03), provides robust solution for wireless multimedia transmission.
`
`HL2 is basically centrally controlled, with the AP/CC announcing the time structure
`
`at the beginning of each MAC frame.
`
`This is in marked contrast to CSMA/CA of the 11a
`
`standard, which is essentially a simple Listen-Before-Talk scheme.
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`HL2 allows the dynamic allocating of new frequencies (Dynamic Frequency
`
`Selection, DFS), as well as Transmitter Power Control (TPC).
`
`In contrast thereto, 11a keeps
`
`operating at a single carrier frequency, once it has been selected. Both systems apply Link
`
`Adaptation (LA), which is a flexible interference-dependent selection of modulation and
`
`coding.
`
`Both of the 1 la and HL2 standards are intended to operate in the license exempt band
`
`5.1 .. 5.8 GHZ in Europe, and similar U—NII bands in the US and Japan. There therefore
`
`exists a need for a set of frequency sharing rules (FSR3), or etiquettes, providing the fair
`
`co-existence of these two broadband communication standards.
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`
`This problem hasbeen addressed in COEXISTENCE OF IEEE 802.11 AND ETSI
`
`BRAN HiperLAN/2: THE PROBLEM OF FAIR RESOURCE SHARING IN THE
`
`LICENSE EXEMPT BAND AT 5 GHz, Marigold, et al., IEEE Conference on Third
`
`Generation Wireless Communications, 14-16 June 2000, San Francisco, USA, available
`
`online
`
`at
`
`<<http://www.comnets.rwth-aachen.de/cgi-bin/paper-download.pl?BIBID=MaI-lmaiWij—3G
`
`wireless2000&LANG=en&USER=smd>>, hereinafter referred to as "Mangold".
`
`Mangold describes a simulated scenario wherein an 802.11 AP communicates with
`
`two MTs which are each at a distance of a few meters from the 802.11 AP, and a nearby HL2
`
`AP communicates with two MTs which are also each at a distance of a few meters from the
`
`AP, and both systems are transmitting their packets at the same frequency using the same
`
`carrier.
`
`As noted therein:
`
`The 802.11 packets sent after carrier sensing and after Ready To Send (RTS)
`
`and Clear To Send (CTS) bursts very often interfere with the BCH PDU of
`
`HL2 at the beginning of the MAC frame. Once the BCH of the HL2 is
`
`corrupted, the related MAC frame gets lost and no traffic can be carried in the
`
`uplink (UL). This is due to the fact that the BCH of HL2 is interfered by
`
`many 802.11 packets. Although the whole transmission period of an 802.11
`
`packet may fit into the not used parts of the HL2 frame, at least with small
`
`loads, i.e., longer periods in the HL2 MAC frame which are not used, the BCH
`
`is very often corrupted. And, if the traffic load in both systems is close to its
`
`maximum, the HL2 frame is substantially filled up, the 802.11 system will fail
`
`to operate and the HL2 system reaches nearly its maximum.
`
`It can therefore
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`be seen that without appropriate FSRS, mutual interferences will lead to poor
`
`QoS for both system types.
`
`Mangold discusses possible solutions to the problem, as follows.
`
`.
`
`In order to avoid the transmission of a competing 802.11 terminal in not used
`
`5
`
`parts of the HL2 MAC frame, LA is applied and a modulation and coding
`
`scheme is selected that fills up the MAC frame as much as possible. If this
`
`measure does not suffice to fill the MAC frame completely, the AP would
`
`broadcast system related management information in the not used parts of the
`
`MAC frame to fill it completely and avoid a 802.11 terminal to start its own
`
`10
`
`transmission. Since the random access slots of the RACH might be used in
`
`HL2, and could therefore allow the transmission of an 802.11 terminal, the AP
`
`will transmit negative acknowledgement (NAK) at the slot as soon as it has
`
`detected an unused random access slot.
`
`This could be performed by
`
`transmitting energy bursts after detecting that no access happened. No idle
`
`15
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`periods longer than the inter frame space necessary for starting a transmission
`
`of 802.11 occur, and the 802.11 systems do not interfere in times when HL2 is
`
`required to guarantee QoS for real-time traffic such as voice or multimedia.
`
`Marigold proposes a transmission suppression mechanism, wherein the transmission
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`20
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`of 802.11 frames will be suppressed by HL2, so that it will never have the chance to be used
`
`when operated in HL2 environment. Therefore, this is not a co-existence solution, it is
`
`merely an approach to interference avoidance (HL2 can be operated but 802.11 can not).
`
`In parallel to HiPerLAN/2 standardization work, the Multimedia Mobile Access
`
`Communications (IVIMAC) Association in Japan has started to develop different high-speed
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`radio access systems for business and home applications at 5 GHz. One of these systems for
`
`business applications in corporate and public networks is aligned with HiPerLAN /2 at both
`
`the PHY layer and the DLC layer.
`
`In addition, the PHY layer of IEEE 802.11 standard in the
`
`5 GHZ band is harmonized with that of HiPerLAN /2.
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`30
`
`General Glossary
`
`Unless otherwise noted, or as may be evident from the context of their usage, any terms,
`
`abbreviations, acronyms or scientific symbols and notations used herein are to be given their
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`ordinary meaning in the technical discipline to which the invention most nearly pertains. The
`
`following glossary ofterms is intended to lend clarity and consistency to the various descriptions
`
`contained herein, as well as in any prior art documents which may be cited:
`
`3GPP
`ACH
`
`ACK
`AP
`ATM
`BCH
`
`BPSK
`BRAN
`BSS
`
`3rd Generation Partnership Project
`Access feedback CHannel
`
`acknowledge/acknowledgment
`access point
`Asynchronous Transfer Mode
`Broadcast Channel
`A
`
`Binary Phase Shift Keying
`Broadband Radio Access Networks
`Basic Service Set
`‘
`
`CC
`CCK
`CEPT/ERC
`
`CRC
`CSMA/CA
`CSMA/CD
`CTS
`DCF
`
`Central Controller (HL2)
`Complementary Code Keying
`Conference Européenne des"Postes et Telecommunications (European
`Conference of Postal and Telecommunications Administrations)/
`European Radiocommunication Committee
`Cyclic Redundancy Check
`Carrier Sense Multiple Access with Collision Avoidance
`Carrier Sense Multiple Access with Collision Detection
`Clear to Send
`Distribution Coordination Function
`
`DFS
`DHCP
`DIL
`
`DL
`
`DS
`DSSS
`EIRP
`ESS
`
`Ethernet
`ETSI
`FCC
`FCH
`
`Dynamic Frequency Selection
`Dynamic Host Configuration Protocol
`Direct Link
`
`Downlink
`
`distribution system
`direct sequence spread spectrum
`Effective Isotropically Radiated Power
`Extended Service Set
`
`A LAN protocol. See IEEE 802.2
`European Telecommunications Standards Institute
`Federal Communications Commission (USA)
`Frame CHannel
`
`Frequency Hopping Spread Spectrum
`FHSS
`Frequency Sharing Rules
`FSRs
`Gaussian Frequency Shift Keying
`GFSK
`GigaHertz
`GHz
`Gaussian Minimum Shift Keying
`GMSK
`HIPERLAN High Performance Radio Local Area Network ("HL2", "H2")
`HL2
`HiperLAN/2
`IBSS
`Independent Basic Service Set
`IEEE 802.11 Wireless LAN protocol ("Ila")
`IEEE 802.2
`Ethernet protocol
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`IEEE
`
`IETF
`
`IPSec
`ISA
`ISM
`ISO
`
`LA
`LAN
`LLC
`MAC
`
`MMAC
`ms
`
`MTS
`
`NAV
`NIC
`NOS
`OFDM
`PC
`PCF
`PCI
`PDU
`PHY
`PPM
`PRNG
`
`QAM
`QoS
`QPSK
`RACH
`RC4
`RCH
`RTS
`SEA
`SNMP
`STA
`TCP/IP
`TDD
`
`TDMA
`TPC
`UL
`UMTS
`U—NII
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`ll
`
`Institute of Electrical and Electronics Engineers
`Internet Engineering Task Force
`Internet Protocol
`
`Internet Protocol security
`Integrated Services Architecture
`Industry, Scientific, and Medical
`International Organization for Standardization
`kilometer
`
`Link Adaptation
`Local Area Network
`
`_
`Logical Link Control
`Media (or Medium) Access Control
`management information base
`Radio Equipment Inspection and Certification Institute (Japan)
`Multimedia Mobile Access Communications
`millisecond
`Mobile Terminals
`milliWatt
`network allocation vector
`network interface card
`
`network operating system
`Orthogonal Frequency Division Multiplexing
`Personal Computer
`Point Coordination Function
`
`Peripheral Component Interconnect
`Protocol Data Unit
`
`physical
`Pulse Position Modulation
`
`pseudo random number generator
`quadrature amplitude modulation
`Quality of Service
`Quadrature Phase Shift Keying
`Random Access Channel
`
`Ron’s Code or Rivest’s Cipher
`Random CHanne1
`
`ready-to-send (or Request to Send)
`Spokesman Election Algorithm
`Simple Network Management Protocol
`Station (802.11)
`Transmission Control Protocol/Intemet Protocol
`
`Time Division Duplex
`Time Division Multiplex
`Transmitter Power Control
`
`Uplink
`Universal Mobile Telecommunications System
`Unlicensed National Information Infiastructure
`Watt
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`WECA
`WBP
`WLAN
`
`Wireless Ethernet Compatibility Alliance
`Wired Equivalent Privacy
`Wireless Local Area Network
`
`SUMMARY OF THE INVENTION
`
`What is needed is a unified communications protocol for wireless local area networks
`
`(WLANs) which provides for the fair co-existence of the lla and HL2 broadband
`
`communications standards. These two incompatible standards are planned to operate on the
`
`same frequency bands,
`
`leading to incompatible products and impossible interoperability
`
`between the two environments. As the industry has learned in the past, multiple standards,
`
`product incompatibilities and poor: interoperability impose a major hurdle for wide public
`
`acceptance.
`
`The present
`
`invention provides such a unified communications protocol which
`
`ensures that these two standards may fairly co-exist, without being able to communicate with
`
`one another and without exchanging resource requests or grants, and which allows each
`
`system the opportunity to protect their active terminal (MT) during communication phases
`
`and to guarantee a certain Quality of Service (QoS).
`
`According to the invention, a technique is provided for combining the 1121 and I-IL2
`
`standards, enabling protocol co-existence, and improved interoperability between these‘ two
`
`WLAN standards, thereby providing a globally-harmonized, synergistic 5GHz Wireless LAN
`
`solution. The principle is generally to combine the best from the two standards, while
`
`maintaining one coherent, and relatively simple solution. Broadly stated, the ultimate object
`
`of the present invention is providing a unified standard which fulfills the following
`
`conditions:
`
`- Achieving all—around interoperability, wherein the same device is able to connect, be
`
`serviced and to serve in any of the home, office and public environment. The products
`
`co-exist and share infrastructure and resources.
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`15
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`25
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`- Delivering all the required functionality without sacrificing simplicity. Modern
`
`Wireless LAN applications require various advanced features, including the ability to deliver
`wide variety of protocols (e.g., Ethernet, IP, IEEE 1394, and others), quality of service (QoS)
`
`30
`
`support, and robust privacy support (encryption, authentication). Regulations in many
`
`countries require radio link fimctionality for dynamic frequency selection and transmission
`
`power control. All those features are integrated into the unified standard of the present
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`invention, without overloading the system with urmecessary complexities, keeping the
`
`standard as simple to use and implement as possible.
`
`The present invention can be implemented in a stepwise manner that is suitable to be
`
`introduced in phases, each of which may be considered to be an embodiment of the invention,
`
`as follows:
`
`Phase 1
`
`This phase enables Co~existence and partial interoperability of both the
`
`1 la and HL2 standards at minimum development effort, and divided into two sub—phases:
`
`Phase 1.1
`
`This sub—phase is based on the original APs (E-AP & M-AP)
`
`with a partial arbitrator entity (ARB) added to one of the APs.
`
`10
`
`Phase 1.2
`
`This sub-phase is based on one U-AP.
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`15
`
`20
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`25
`
`Phase 2
`
`This phase enables co-existence and full interoperability of both the
`
`1 la and HL2 standards
`
`Generally, in the first phase, there is one standard, with partial interoperability among
`
`different environments. The PHY layer is 11a, and the MAC layer is essentially a simplified
`
`version of HL2 superimposed upon the basic lla MAC. This results in:
`
`High QoS
`
`Full Co-existence
`
`Partial Interoperability
`Generally, in the second phase, there is universal (global) standard. The PHY layer is
`
`1 la, and the MAC layer is a hybrid (combination) of I-IL2 and 11a. This results in:
`
`High QoS
`
`Full Co—existence
`
`Full Interoperability
`
`In the first phase (or "intermediate solution“), co—existence is achieved between the
`
`two standards by dynamically dividing the time domain of each subnetwork at its Access
`Point (AP),_between the 11a and the HL2 devices. The time division between these different
`
`devices is performed by an Arbitrator (ARB) entity. For example, this will enable a laptop
`
`user working mainly in a corporate environment based on 11a to also