(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2004/0141522 A1
`(43) Pub. Date:
`Jul. 22, 2004
`Texerman et al.
`
`US 20040141522A1
`
`(54) COMMUNICATIONS PROTOCOL FOR
`WIRELESS LAN HARMONIZING THE IEEE
`802.11A AND ETSI HIPERLA/Z STANDARDS
`
`(76) Inventors: Yossi TeXerman, Modiin (IL); Oren
`Davidi, Ramat Gan (IL)
`
`Correspondence Address:
`Mark M Friedman
`Bill Polkinghorn
`Dicovery Dispatch
`9003 Florin Way
`Upper Marlboro, MD 20772 (US)
`
`Appl. No.:
`
`10/344,163
`
`PCT Filed:
`
`Jul. 11, 2001
`
`PCT No.:
`
`PCT/US01/21796
`
`Related US. Application Data
`
`(21)
`(22)
`(86)
`
`(60) Provisional application No. 60/223,993, ?led on Aug.
`9, 2000. Provisional application No. 60/230,412, ?led
`on Sep. 6, 2000.
`
`Publication Classi?cation
`
`(51) Int. Cl? ...................................................... ..H04J 3/16
`(52) US. Cl. .......................................... .. 370/466; 370/338
`
`(57)
`
`ABSTRACT
`
`A uni?ed communications protocol for Wireless local area
`networks (WLANs) (400) Which provides for the fair co
`existence of the IEEE 802.11a (“11a”) and HiPerLAN/2
`(“HL2”), broadband communications standards. Wireless
`network devices (MT’s) operating in accordance With 11a
`and HL2 may co-eXist Without interference by partitioning a
`2 ms periodic lime domain, based on the HL2 standard, into
`a ?rst slice for use by 11a MT’s 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 ?rst access Point
`(E-AP) handles communication With the E-MT’s, and a
`second Access Point (M-AP) handles communications With
`the e-MTSs and the M-MT’s. In this manner, convergence is
`provided betWeen 11a and HL2, providing users With the
`best or both Worlds, e.g., full interoperability, QoS and
`co-eXistence.
`
`is I,
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`
`ERIC-1033
`Ericsson v. IV, IPR2014-01195
`Page 1 of 15
`
`

`
`Patent Application Publication
`
`Jul. 22, 2004 Sheet 1 0f 2
`
`US 2004/0141522 A1
`
`<:
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`
`ERIC-1033
`Page 2 of 15
`
`

`
`Patent Application Publication Jul. 22, 2004 Sheet 2 0f 2
`
`US 2004/0141522 A1
`
`Figure 4
`
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`
`ERIC-1033
`Page 3 of 15
`
`

`
`US 2004/0141522 A1
`
`Jul. 22, 2004
`
`COMMUNICATIONS PROTOCOL FOR WIRELESS
`LAN HARMONIZING THE IEEE 802.11A AND ETSI
`HIPERLA/2 STANDARDS
`
`TECHNICAL FIELD OF THE INVENTION
`
`[0001] The invention relates to Wireless communications
`and, more particularly, to a communications protocol (stan
`dard) for Wireless local area netWork (WLAN) applications,
`taking into account the IEEE 802.11a standard and the ETSI
`HiPerLAN/2 standard.
`
`BACKGROUND OF THE INVENTION
`
`[0002] A local area netWork (LAN) is a netWork of inde
`pendent computers, usually con?ned 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.
`[0003] Ethernet is the most popular physical layer LAN
`technology in use today. The Institute for Electrical and
`Electronic Engineers (IEEE) de?nes the Ethernet standard as
`IEEE Standard 802.3. This standard de?nes rules for con
`?guring an Ethernet netWork as Well as specifying hoW
`elements in an Ethernet netWork interact With one another.
`By adhering to the IEEE standard, netWork equipment and
`netWork protocols can communicate ef?ciently.
`
`[0004] 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.
`
`[0006] 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
`bene?t from WLAN s 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.
`
`[0007] The 5 GigaHertZ (GHZ) band is of particular inter
`est for high bandWidth WLAN 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 Radi
`ated 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.
`
`[0008] TWo WLAN standards (protocols) for the 5 GHZ
`band have emerged, the IEEE 802.11a (Hereinafter referred
`to as “802.11” or “11a”) and HiPerLAN/2 (hereinafter
`referred to as “HL2”). Acommon vieW in the industry is that
`these tWo standards are in competition With one another.
`Whereas the Ethernet-based 11a standard is particularly
`Well-suited to the business environment, the multimedia
`based HL2 standard is particularly Well-suited to the home
`environment. As the industry has learned from past experi
`ence, competing standards and uncertainties about standard
`adoption and interoperability issues can greatly adversely
`the proliferation of products.
`
`Protocol-Speci?c De?nitions & Abbreviations
`
`[0005] The ‘Ether’ part of Ethernet denotes that the system
`is not meant to be restricted for use on only one medium
`type. Copper cables, ?bre cables and radio Waves can be
`used.
`
`[0009] Each of the 11a and HL2 standards utiliZes its oWn
`de?nitions and abbreviations. It is therefore useful, for
`purposes of this document, to establish a common terminol
`ogy, as folloWs:
`
`Ethernet elements
`Multimedia elements
`Co-existence
`
`11a elements may be referred to as Ethernet elements.
`HL2 elements may be referred to as Multimedia elements.
`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.
`The ability of tWo Wireless elements, each consistent With a
`different protocol, to exchange information directly.
`This term is used to describe a so-called “base station” in both
`the 11a and HL2 standard
`With reference to the present
`invention, the following pre?xes Will be used.
`Ethernet Access Point (consistent With the 11a term-AP/PC)
`Multimedia Access Point (consistent With the HL2 term-AP/CC)
`Uni?ed Access Point (a “coined” term)
`
`Full Interoperability
`
`Access Point
`
`E-AP
`M-AP
`U-AP
`
`ERIC-1033
`Page 4 of 15
`
`

`
`US 2004/0141522 A1
`
`Jul. 22, 2004
`
`-continued
`
`Mobile Terminal
`
`E-MT
`M-MT
`U-MT
`
`This term is used to describe all wireless network elements
`except the Access Point, including stationary terminals, in both
`the 11a and HL2 standard
`With reference to the present
`invention, the following pre?xes will be used.
`Ethernet Mobile Terminal (consistent with the 11a term-STA)
`Multimedia Mobile Terminal (consistent the HL2 term-MT)
`Uni?ed Mobile Terminal (a “coined” term)
`
`IEEE 802.11a (“11a”)
`[0010] The IEEE 802.11 (“11a”) standard is a broadband
`communication standard for WLANs, and de?nes two
`pieces of equipment, a wireless station (STA, herein “MT”),
`which is usually a personal computer (PC) equipped with a
`wireless network interface card (MC), 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 802.1d bridging standard. The AP acts as the
`base station for the wireless network, aggregating access for
`multiple MTs onto the wired network. Wireless stations can
`be 802.11 PC Card, PCI, or ISA NICs, or embedded solu
`tions in non-PC clients (such as an 802.11-based telephone
`handset).
`[0011] The 11a standard de?nes two modes of operation—
`an infrastructure mode and an ad-hoc mode. In the infra
`structure mode, the wireless network consists of at least one
`AP connected to the wired network infrastructure and a set
`of MTs. This con?guration 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 cor
`porate wireless LANs require access to the wired LAN for
`services (?le 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 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).
`
`[0012] The 11 a 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.
`
`[0013] The 11a MAC layer is responsible-for how a wire
`
`
`
`less station (MT) associates with an access point 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 perfor
`mance characteristics. If it determines that this is the case,
`the MT reassociates with the new AP, tuning to the radio
`channel to which thatAP 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 traf?c on the
`original access point. In the latter case this function is known
`as “load balancing,” since its primary function is to distrib
`ute the total WLAN load most ef?ciently across the available
`wireless infrastructure.
`
`[0014] A MAC-layer problem speci?c 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 speci?es 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.
`
`HiperLAN/2 (HL2)
`
`[0015] 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 herein
`below. HL2 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 covering a certain geographical area. In this mode, a mobile
`
`terminal (MT) communicates with other mobile terminals
`(Ts) 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 envi
`ronments, 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.
`
`[0016] 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 channel con
`?gurations.
`
`ERIC-1033
`Page 5 of 15
`
`

`
`US 2004/0141522 A1
`
`Jul. 22, 2004
`
`[0017] An intermediate layer, the Channel Access and
`Control (CAC) sub-layer, deals With channel access signal
`ing and protocol operation required to support packet pri
`ority. A pseudo-hierarchically independent access mecha
`nism 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 single, vari
`able length radio pulse preceding packet data. EY-NPMA
`provides good residual collision rate performance for even
`large numbers of simultaneous channel contenders.
`
`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 (doWn
`link). 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 ful?ll the regulatory requirements in
`Europe to decrease interference to other systems using the
`same 5 GHZ band.
`
`[0018] The HL2 standard also includes a Data Link Con
`trol (DLC) layer. TWo speci?cations address the basic part of
`the DLC layer. The ?rst one includes the basic data transport
`functions consisting of Error Control protocol and Medium
`Access Control (MAC) protocol. The second speci?cation
`de?nes the Radio Link Control (RLC) Sublayer that is used
`for exchanging data in the control plane betWeen an access
`point
`and a mobile terminal
`Furthermore, tWo
`speci?cations are developed for Home and Business pro?les
`of the DLC. The air interface of HL2 is based on Time
`Division Duplex (TDD) and dynamic Time Division Mul
`tiplex (TDMA).
`[0019] The HL2 standard also speci?es Convergence Lay
`ers (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 ?xed or
`variable siZe into ?xed-siZe DLC Service Data Units that is
`used Within the DLC. Convergence layers have been devel
`oped for Ethernet (IP based) applications, cell based core
`netWorks as ATM and for IEEE1394 protocols and applica
`tions.
`
`[0020] The HL2 standard de?nes a set of protocols (mea
`surements and signaling) to provide support for a number of
`radio netWork functions, eg Dynamic Frequency Selection
`(DFS), link adaptation, handover, multi beam antennas and
`poWer control, Where the algorithms are vendor speci?c. The
`supported radio netWork functions alloW cellular deploy
`ment 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 communica
`tions. This is performed by the DFS, Which alloWs several
`operators to share the available spectrum by avoiding the use
`of interfered frequencies.
`
`[0021] Performance is one of the most important factors
`When dealing With Wireless LANs. In contrast to other
`radio-based systems, data traf?c 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 mea
`sured. Among these are the topography of the landscape in
`general, elevations in the landscape that might cause shad
`oWs Where connectivity is unstable or impossible, environ
`ments With many signal-re?ection surfaces, environments
`With many signal-absorbing surfaces, quality of the Wireless
`equipment, placement of the Wireless equipment, number of
`stations, proximity to installations that generate electronic
`noise, and many more.
`[0022] To cope With the varying radio link quality (inter
`ference 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
`
`[0023] Atypical HL2 MAC Frame is of 2 ms duration, and
`comprises the folloWing functions/phases:
`
`BCH
`FCH
`ACH
`DL
`DIL
`UL
`RCH
`
`Broadcast CHannel
`Frame CHannel
`Access feedback CHannel
`DoWnlink
`Direct Link
`Uplink
`Random Channel(s)
`
`Frequency Sharing Rules (FSRs)
`
`[0024] Both of the 11a and HL2 standards have chosen the
`same OFDM-based approach in the PHY layer. Therefore,
`harmoniZation of the PHY layer is relatively straightfor
`Ward, 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 11a standard CSMA/
`CA MAC is optimiZed for Wireless data communication,
`providing simple and ?eld proven solution for Wireless
`Ethernet and IP, the HL2 standard, With its build-in support
`for quality of service (QoS), provides robust solution for
`Wireless multimedia transmission.
`
`[0025] 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 11 a standard, Which is essentially a simple Listen
`Before-Talk scheme.
`
`[0026] HL2 alloWs the dynamic allocating of neW frequen
`cies (Dynamic Frequency Selection, DFS), as Well as Trans
`mitter 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 ?exible interference-dependent selection of modulation
`and coding.
`
`[0027] Both of the 11a 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
`(FSRs), or etiquettes, providing the fair co-existence of these
`tWo broadband communication standards.
`
`[0028] This problem has been addressed in COEIHST
`ENCE OF IEEE 802.11 AND ETSI BRAN HiperLAN/Z:
`THE PROBLEM OF FAIR RESOURCE SHARING IN THE
`LICENSE EXEMPT BAND AT 5 GHZ, Mangold, et al., IEEE
`Conference on Third Generation Wireless Communications,
`Jun. 14-16, 2000, San Francisco, USA, available online at
`<<http://WWW.comnets.rWth-aachen.de/cgi-bin/paper
`
`ERIC-1033
`Page 6 of 15
`
`

`
`US 2004/0141522 A1
`
`Jul. 22, 2004
`
`download.p1?B1BID=MaHmaiWij-3G
`wireless2000&LANG=en&USER=smd>>,
`referred to as “Mangold”.
`
`hereinafter
`
`addition, the PHY layer of IEEE 802.11 standard in the 5
`GHZ band is harmoniZed with that of HiPerLAN/2.
`
`[0029] 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:
`
`[0030] 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 traf?c 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 ?t
`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 traf?c
`load in both systems is close to its maXimum, the HL2 frame
`is substantially ?lled up, the 802.11 system will fail to
`operate and the HL2 system reaches nearly its maXimum. It
`can therefore be seen that without appropriate FSRs, mutual
`interferences will lead to poor QoS for both system types.
`
`[0031] Mangold discusses possible solutions to the prob
`lem, as follows.
`
`[0032] In order to avoid the transmission of a competing
`802.11 terminal in not used parts of the HL2 MAC frame,
`LA is applied and a modulation and coding scheme is
`selected that ?lls up the MAC frame as much as possible. If
`this measure does not suf?ce to ?ll the MAC frame com
`pletely, the AP would broadcast system related management
`information in the not used parts of the MAC frame to ?ll it
`completely and avoid a 802.11 terminal to start its own
`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 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 traf?c such
`as voice or multimedia.
`
`[0033] Mangold proposes a transmission suppression
`mechanism, wherein the transmission 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).
`[0034] In parallel to HiPerLAN/2 standardiZation work,
`the Multimedia Mobile Access Communications (MMAC)
`Association in Japan has started to develop different high
`speed radio access systems for business and home applica
`tions at 5 GHZ. One of these systems for business applica
`tions in corporate and public networks is aligned with
`HiPerLAN/2 at both the PHY layer and the DLC layer. In
`
`General Glossary
`
`[0035] Unless otherwise noted, or as may be evident from
`the conteXt of their usage, any terms, abbreviations, acro
`nyms or scienti?c symbols and notations used herein are to
`be given their ordinary meaning in the technical discipline to
`which the invention most nearly pertains. The following
`glossary of terms 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
`CC
`CCK
`CEPT/ERC
`
`CRC
`CSMA/CA
`CSMA/CD
`CTS
`DCF
`DFS
`DHCP
`DIL
`DL
`DS
`DSSS
`EIRP
`ESS
`Ethernet
`ETSI
`FCC
`FCH
`FHSS
`FSRs
`GFSK
`GHZ
`GMSK
`HIPERLAN
`
`HL2
`IBSS
`IEEE 802.11
`IEEE 802.2
`IEEE
`IETF
`IP
`IPSec
`ISA
`ISM
`ISO
`km
`LA
`LAN
`LLC
`MAC
`MIB
`MKK
`
`MMAC
`
`3rd Generation Partnership Project
`Access feedback CHannel
`acknowledge/acknowledgment
`access point
`Asynchronous Transfer Mode
`Broadcast Channel
`Binary Phase Shift Keying
`Broadband Radio Access Networks
`Basic Service Set
`Central Controller (HL2)
`Complementary Code Keying
`Conference Europeenne
`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
`Dynamic Frequency Selection
`Dynamic Host Con?guration 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
`Frequency Sharing Rules
`Gaussian Frequency Shift Keying
`GigaHertZ
`Gaussian Minimum Shift Keying
`High Performance Radio Local Area
`Network (“HL2”, “H2”)
`HiperLAN/2
`Independent Basic Service Set
`Wireless LAN protocol (“11a”)
`Ethernet protocol
`Institute of Electrical and Electronics Engineers
`Internet Engineering Task Force
`Internet Protocol
`Internet Protocol security
`Integrated Services Architecture
`Industry, Scienti?c, 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 Certi?cation
`Institute (Japan)
`Multimedia Mobile Access Communications
`
`ERIC-1033
`Page 7 of 15
`
`

`
`US 2004/0141522 A1
`
`Jul. 22, 2004
`
`-continued
`
`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 CHannel
`ready-to-send (or Request to Send)
`Spokesman Election Algorithm
`Simple Network Management Protocol
`Station (802.11)
`Transmission Control Protocol/Internet Protocol
`Time Division Duplex
`Time Division Multiplex
`Transmitter Power Control
`Uplink
`Universal Mobile Telecommunications System
`Unlicensed National Information Infrastructure
`Watt
`Wireless Ethernet Compatibility Alliance
`Wired Equivalent Privacy
`Wireless Local Area Network
`
`ms
`MTs
`mW
`NAV
`NIC
`NOS
`OFDM
`PC
`PCF
`PCI
`PDU
`PHY
`PPM
`PRNG
`QAM
`QoS
`QPSK
`RACH
`RC4
`RCH
`RIS
`SEA
`SNMP
`STA
`TCP/IP
`TDD
`TDMA
`TPC
`UL
`UMTS
`U-NIT
`W
`WECA
`WEP
`WLAN
`
`SUMMARY OF THE INVENTION
`
`[0036] What is needed is a uni?ed communications pro
`tocol for wireless local area networks (WLANs) which
`provides for the fair co-existence of the 11a and HL2
`broadband communications standards. These two incompat
`ible 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.
`
`[0037] The present invention provides such a uni?ed com
`munications 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).
`[0038] According to the invention, a technique is provided
`for combining the 11a and HL2 standards, enabling protocol
`co-existence, and improved interoperability between these
`two WLAN standards, thereby providing a globally-harmo
`niZed, synergistic 5 GHZ Wireless LAN solution. The prin
`ciple is generally to combine the best from the two stan
`dards, while maintaining one coherent, and relatively simple
`solution. Broadly stated, the ultimate object of the present
`invention is providing a uni?ed standard which ful?lls the
`following conditions:
`interoperability,
`all-around
`[0039] Achieving
`wherein the same device is able to connect, be
`
`serviced and to serve in any of the home, of?ce and
`public environment. The products co-exist and share
`infrastructure and resources.
`[0040] Delivering all the required functionality with
`out sacri?cing simplicity. Modern Wireless LAN
`applications require various advanced features,
`including the ability to deliver wide variety of pro
`tocols (e.g., Ethernet, IP, IEEE 1394, and others),
`quality of service (QoS) support, and robust privacy
`support (encryption, authentication). Regulations in
`many countries require radio link functionality for
`dynamic frequency selection and transmission power
`control. All those features are integrated into the
`uni?ed standard of the present invention, without
`overloading the system with unnecessary complexi
`ties, keeping the standard as simple to use and
`implement as possible.
`
`[0041] 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:
`[0042] Phase 1 This phase enables Co-existence and
`partial interoperability of both the 11a and HL2
`standards at minimum development effort, and
`divided into two sub-phases:
`
`[0043] Phase 1.1 This sub-phase is based on the
`original APs (E-AP & M-AP) with a partial arbi
`trator entity (ARB) added to one of the APs.
`
`[0044] Phase 1.2 This sub-phase is based on one
`U-AP.
`
`[0045] Phase 2 This phase enables co-existence and
`full interoperability of both the 11a and HL2 stan
`dards
`
`[0046] Generally, in the ?rst phase, there is one standard,
`with partial interoperability among different environments.
`The PHY layer is 11a, and the MAC layer is essentially a
`simpli?ed version of HL2 superimposed upon the basic 11a
`MAC. This results in:
`[0047] High QoS
`[0048] Full Co-existence
`[0049] Partial Interoperability
`[0050] Generally, in the second phase, there is universal
`(global) standard. The PHY layer is 11a, and the MAC layer
`is a hybrid (combination) of HL2 and 11a. This results in:
`[0051] High QoS
`[0052] Full Co-existence
`[0053] Fu