(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
`
`1111111111111111 IIIIII 111111111111111 lllll 1111111111111111111111111111111 IIII IIII IIII
`
`(43) International Publication Date
`17 October 2002 (17.10.2002)
`
`PCT
`
`(10) International Publication Number
`WO 02/082751 A2
`
`(51) International Patent Classification 7:
`
`H04L 12/56
`
`(21) International Application Number:
`
`PCT/SE02/00706
`
`(22) International Filing Date:
`
`9 April 2002 (09.04.2002)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`English
`
`English
`
`(30) Priority Data:
`60/282,191
`10/117,128
`
`9 April 2001 (09.04.2001) US
`8 April 2002 (08.04.2002) US
`
`(71) Applicant: TELEFONAKTIEBOLAGET LM ERICS(cid:173)
`SON (PUBL) [SE/SE]; S-126 25 Stockholm (SE).
`
`(72) Inventor: LARSSON, Peter; Ballonggatan 2, S-169 71
`Solna (SE).
`
`(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, EC, 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, OM, PH, PL, PT, RO, RU, SD, SE, SG,
`SI, SK, SL, TJ, TM, TN, TR, TT, TZ, UA, UG, UZ, VN,
`YU, ZA, ZM, ZW.
`
`(84) Designated States (regional): ARIPO patent (GH, GM,
`KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZM, ZW),
`Eurasian patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, 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, GQ, GW, ML, MR,
`NE, SN, TD, TG).
`
`Published:
`without international search report and to be republished
`upon receipt of that report
`
`(74) Agent: GULLSTRAND, Malin; Ericsson Radio Systems
`AB, Patent Unit Research, S-164 80 Stockholm (SE).
`
`For two-letter codes and other abbreviations, refer to the "Guid(cid:173)
`ance Notes on Codes and Abbreviations" appearing at the begin(cid:173)
`ning of each regular issue of the PCT Gazette.
`
`!!!!!!!! --iiiiiiii
`iiiiiiii -iiiiiiii --!!!!!!!!
`
`!!!!!!!! -iiiiiiii
`
`iiiiiiii
`
`M
`< - - - - - - - - - - - - - - - - - - -
`,-...1 (54) Title: INSTANTANEOUS JOINT TRANSMIT POWER CONTROL AND LINK ADAPTATION FOR RTS/CTS BASED
`I.I) CHANNEL ACCESS
`t---.
`~ (57) Abstract: A method for closed loop link adjustment based on a Request To Send-Clear To Send (RTS-CTS) channel access
`Q
`scheme includes the following steps. Designating a station as an originating station. Transmitting a RTS frame with predetermined
`-.... transmit power from an originating station, prior to an intended DATA transmission, sounding the channel such that reception char-
`~ acteristics can be evaluated at a designated receiving station. Transmitting, in response to the originating station, a CTS frame with
`a predetermined transmit power from the receiving station with directives of link adjustments. Transmitting a DATA frame from the
`0 originating station to the receiving station frame complying with link adjustment directives to the extent of the originating stations
`> capabilities. And, transmitting an acknowledge (ACK) frame in response to the originating stations from the receiving station indi(cid:173)
`
`;;, eating result of DATA frame reception.
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 1 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-1-
`
`INSTANTANEOUS JOINT TRANSMIT POWER CONTROL AND
`LINK ADAPTATION FOR RTS/CTS BASED CHANNEL ACCESS
`
`This application claims priority from U.S. Provisional Application No.
`
`60/282,191, filed on 09 April 2001 in the English language, which is hereby
`
`5
`
`incorporated by reference.
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The invention relates to the field of wireless communications, in
`
`particular to transmit power control and link adaptation techniques and
`
`10
`
`mechanisms.
`
`2. Background Information
`
`The IEEE 802.11 is a wireless LAN (Local Area Network) standard
`
`that has beeri standardized by IEEE (Institute of Electrical & Electronics
`
`Engineers). The IEEE 802.11 wireless LAN standard is currently undergoing a
`
`15
`
`process of extending the standard with QoS (Quality of Service) features. The
`
`objective is to enable, for example, computers or multimedia devices to
`
`communicate under QoS constraints. This standard extension goes under the name
`
`IEEE 802.lle and is managed by the so-called task group e, TGe.
`
`Recently, the IEEE 802 .11 standard was also extended with a. new
`
`20
`
`physical layer allowing higher data rates than the previous physical layer. Various
`
`data rates are enabled through several code rates and signal constellations. The
`
`purpose is to allow link adaptation depending on the channel quality. The high
`
`rate PHY (physical layer) on the so-called 5 GHz band is called IEEE 802.1 la and
`
`is based on OFDM (Orthogonal Frequency Division Multiplexing). The
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 2 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-2-
`
`corresponding so-called 2.4 GHz band PHY is called IEEE 802. l lb and uses
`
`single carrier modulation schemes.
`
`IEEE 802.11 operates either in a DCF (Distributed Coordination
`
`Function) or a PCF (Point Coordination Function) mode. The former is for
`
`5
`
`distributed operation and the latter for centralized control from an access point,
`
`AP. So far the PCF mode has not been ratified by implementers as the complexity
`
`is consider to high, instead DCF is used both for the distributed operation as well
`
`as with the AP.
`
`The origin of IEEE 802.11 access scheme is traced back to BTMA
`
`10
`
`(Busy Tone Multiple Access) which was the first proposed method for distributed
`
`control of channel access avoiding the well known hidden terminal problem.
`
`In MACA (Multiple Access with Collision Avoidance), proposed by
`
`Phil Karn in 1980, the introduction of a Request To Send (RTS) and Clear To
`
`Send (CTS), handshake phase prior data transmission solved the idea of distributed
`
`15
`
`reservation. This presented a more feasible basis to build a practical system upon
`
`as it did not divide the frequency band in a channel for data and busy tones, as in
`
`the BTMA scheme. Also the idea of random exponential back off, that was later
`
`used in IEEE 802.11, was introduced in MACA.
`
`In MACAW (Multiple Access with Collision Avoidance for
`
`20 Wireless), the basic mechanism of MACA was refined. Among other things, a
`
`link acknowledgment, ACK, scheme was introduced. The access scheme of IEEE
`
`802.11 is now based to a great extent on principles developed in MACAW.
`
`Other ongoing standardization activities in IEEE 802.11 include the
`
`so-called TGh (Task Group h, i.e. , an IEEE task group for IEEE 802 .1 lh) that
`
`25
`
`has the objective of designing and including transmit power control (TPC), as well
`
`as distributed frequency selection (DFS), in IEEE 802. lla. The purpose of power
`
`control from a standardization point of view is primarily to enable IEEE 802.1 la
`
`stations, ST As, to conform to European regulatory requirements.
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 3 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-3-
`
`As background information, the basic access principles for IEEE
`
`802.11 will now be described. For more detailed information the reader is
`
`referred to the standard IEEE 802.11-1999 (which replaces IEEE 802.11-1997),
`
`the standard IEEE 802.lla-1999 (High data rate on the 5 GHz Band), and the
`
`5
`
`standard IEEE 802.llb-1999 (High data rate on the 2.4 GHz Band). Good and
`
`simple overviews may also be found in a) "Smart Antenna Systems and Wireless
`
`LANs", authored by Garret T. Okamoto and published by Kluwer academic
`
`publishers (ISBN 0-7923-8335-4), and "IEEE 802.11 Handbook, A Designers
`
`Companion", authored by Bob O'Hara and Al Patrick (ISBN 0-7381-1855-9).
`
`10
`
`There are two modes of channel access scheme operation in the
`
`Distributed Co-ordination Function (DCF), one based on' CSMA/CA (Carrier
`
`Sense Multiple Access/Collision Avoidance) and one based on CSMA/CA
`
`including RTS-CTS message exchange. A MIB (Management Information Base)
`
`attribute "dotllRTSThreshold" is used to differentiate the use of the two. MPDUs
`
`15
`
`(MAC Protocol Data Units, where "MAC" stands for Medium Access Control)
`
`shorter than the threshold is sent without RTS-CTSs, whereas longer MPDUs are
`
`sent with RTS-CTSs. The focus here is the RTS-CTS based CSMA/CA
`
`mechanism that enables mitigation of hidden stations and hence in general provides
`
`a more efficient use of the wireless medium.
`
`20
`
`Figures lA-lD show a communication procedure between a station
`
`T and a station R, and related effects on nearby stations E, F, G, H. In Fig. IA,
`
`station T transmits an RTS (Request to Send) signal to the station R. The transmit
`
`range 102 of the station T encompasses the stations R, E and F, but not the
`
`stations H, G. Thus the stations R, E and F receive or overhear the RTS signal,
`
`25
`
`but the stations H, G do not. In a next step shown in Figure lB, in reply to the
`
`RTS signal, the station R sends a CTS (Cleared to Send) reply signal to the station
`
`T. As shown in Figure lB, the transmit range 104 of the station R encompasses
`
`the station F, H but not the stations E, G. After receiving the CTS signal, in
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 4 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-4-
`
`Figure 1 C the station T transmits a DATA signal to the station R, and then in
`
`Figure 1D the station R acknowledges receipt of the DATA signal by sending an
`
`ACK signal or message to the station T.
`
`Since the station H is a hidden station with respect to the station T,
`
`5
`
`it is informed of the intention of station T to transmit via the reply CTS message
`
`sent by the station R (since station H is not hidden from the station R, i.e., it is
`
`within the transmit range 104 of the station R). As a consequence, the station H
`
`will not transmit and disturb ongoing reception by the station R. Stations E and F
`
`will in a similar manner defer channel access to the stations T and R, after
`
`10
`
`overhearing the RTS from the station T and/or the CTS from the station R. As
`
`shown in Figures lA-lD, station G is hidden from both stations T and R, and
`
`therefore will likely not overhear the RTS or CTS, and therefore it may transmit.
`
`Figure 2 illustrates frame formats used in IEEE 802.11, where the
`
`numbers above the boxes indicate the size of the information in the box. Note,
`
`15
`
`Address 4 in the DATA and MANAGEMENT frame exists only for DATA
`
`frames in a wireless DS (Distribution System), and does not exist in
`
`MANAGEMENT frames.
`
`Figure 3 illustrates the frame exchange including RTS and CTS.
`
`When frames are received by stations other than those intended to receive the
`
`20
`
`frames, a so called NAV (Network Allocation Vector) is set according to a
`
`duration value indicated in a field of the frame. This provides an additional
`
`collision avoidance mechanism to the physical channel access sensing and is
`
`therefore called virtual channel sensing. As long as either the physical or virtual
`
`channel sense indicates activities on the channel, a station must remain silent
`
`25
`
`When the channel becomes free, stations start contending for the channel
`
`according to the channel access principles defined in the IEEE 802 .11-1999
`
`standard. In general, the NA V can only be extended if new frames are received.
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 5 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-5-
`
`There exist some special instances when the NAY can be reset as well, but that is
`
`not the normal operation.
`
`Figure 4 illustrates use of RTS-CTS with DATA fragmentation.
`
`Each fragment and ACK then acts as implicit RTS and CTS. Additional fragments
`
`5
`
`are indicated by a bit (field) in the frame control of the fragments.
`
`According to the IEEE 802.11-1999 standard, CTS should be sent
`
`with the same link rate as RTS, and ACK should be sent with the same link rate as
`
`DATA. The original purpose is to enable the originating or transmitting station
`
`(e.g., the station T of Figure 1) to calculate the duration value prior to RTS
`
`10
`
`transmission.
`
`15
`
`20
`
`Figure 5 shows a detailed example of two stations attempting to
`access a channel through the RTS-CTS phase. In Figure 5, each time slot = 9
`microseconds, the SIPS (Short Inter-Frame Spaces) time = 16 microseconds, a
`CCA (carrier sense) time < 4 microseconds, a min CW (Contention Window) =
`15 time slots, a max CW = 1023 time slots, an air propagation time < < 1
`microsecond (in Figure 5, it is O microseconds), DIPS = SIPS + 2 time slots =
`34 microseconds, RTS = 52 microseconds@ 6 megabytes/second (RTS = 24
`microseconds@ 54 megabytes/second), and CTS = 44 microseconds@ 6
`megabytes/second (CTS = 24 microseconds@ 54 megabytes/second).
`International Publication No. WO-9501020 A discloses that each
`
`station in a wireless LAN (Local Area Network), using time-distributed multiple
`
`access control, listens to traffic using the network communications channel, for
`
`example, for spread-spectrum, frequency-hopping transmissions. Each station
`
`constructs its own network allocation vector from the received transmission
`
`25
`
`contents, indicating when the channel will be in use. Message transmission uses
`
`four-way handshaking with two short control packets, "Request to send" (RTS)
`
`and "Clear to send" (CTS). The RTS packet includes the data transmission length,
`
`enabling the various receiving stations in the network to reserve and block their
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 6 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-6-
`
`use of the communications channel over the period of time concerned. The CTS
`
`packet repeats this data length, for the benefit of receiving stations not within
`
`range of the source transmission. This document corresponds to the IEEE 802.11
`
`standard defined in the IEEE 802.11-1999 standard.
`
`5
`
`Some ideas regarding transmission power control in DBTMA (Dual
`
`Busy Tone Multiple Access), are described in S.-L. Wu, Y.-C. Tseng, and J.-P.
`
`Sheu, "Intelligent Medium Access for Mobile Ad Hoc Networks with Busy Tones
`
`and Power Control", Int'l Conf. on Computer Communications and Networks,
`
`1999, pp. 71-76. DBTMA is an extension of BTMA with dual busy tones instead
`
`10
`
`of a single busy tone.
`
`However, power control is not supported in known RTS-CTS based
`
`channel access schemes.
`
`With respect to DBTMA with TPC, BTMA (Busy Tone Multiple
`
`Access) as such is generally not a viable solution for distributed channel access as
`
`15
`
`it is extremely unpractical. It is merely used as a simple system to study in the
`
`academic literature. Also, control messages use maximum Transmit Power (TP),
`
`and therefore it is not possible for control messages to share a channel with data
`
`traffic as that would cause harmful interference peaks for data reception. Another
`
`drawback is that information regarding fixed TP is assumed known at the receiver.
`
`20
`
`In addition, DBTMA with TPC only attempts to solve a problem in a specific
`
`situation, namely in a distributed system where stations are neither associated with
`
`APs, nor associated in a group with other stations. Another drawback is that
`
`asymmetries in interference, link gain, or TP capabilities are not been considered.
`
`There are also additional problems common to each of general RTS-
`
`25
`
`CTS, IEEE 802.11 and DBTMA, namely a) link adaptation has not been
`
`considered in the RTS-CTS framework, and b) asymmetries in terms of link
`
`adaptation capabilities have not been considered.
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 7 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-7-
`
`SUMMARY OF THE INVENTION
`
`Exemplary embodiments of the invention take a more far-reaching
`
`transmit power-control (TPC) approach than outlined IEEE 802.11 TGh, and have
`
`the objective of improving the overall system performance in IEEE 802.1 la as
`
`5
`
`well as other RTS-CTS based channel access scheme to the greatest feasible extent
`
`In doing so, this will implicitly address QoS goals considered in IEEE
`
`802.11 TGe.
`
`A further goal of the invention is to address the issue of link
`
`adaptation (LA) in conjunction with RTS-CTS frame exchange.
`
`10
`
`A further goal of the invention is to address the issue of link
`
`adaptation (LA) in a common framework with TPC.
`
`In accordance with an exemplary embodiment of the invention, a
`
`method for closed loop link adaptation based on a Request To Send-Clear To Send
`
`(RTS-CTS) channel access scheme includes the following steps. Designating a
`
`15
`
`station as an originating station. Transmitting a RTS frame with predetermined
`
`transmit power from an originating station, prior to an intended DATA
`
`transmission, sounding the channel such that reception characteristics can be
`
`evaluated at a designated receiving station. Transmitting, in response to the
`
`originating station, a CTS frame with a predetermined transmit power from the
`
`20
`
`receiving station with directives of link adaptations. Transmitting a DATA frame
`
`from the originating station to the receiving station frame complying with link
`
`adjustment directives to the extent of the originating stations capabilities.
`
`Transmitting an acknowledge (ACK) frame in response to the originating stations
`
`from the receiving station indicating result of DATA frame reception.
`
`25
`
`In accordance with another exemplary embodiment of the invention,
`
`a method for open loop group transmit power control in an infrastructureless
`
`system (i.e. an IBSS or Independent Basic Service Set), includes the following
`
`steps. Transmitting a frame conveying transmit power information for the
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 8 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-8-
`
`corresponding frame to any proximate station. Receiving, by one of the proximate
`
`stations, the frame and determining the path gain based on measured signal
`
`strength of the received frame and respective transmit power information conveyed
`
`in the received frame. Selecting path gains originating from the same group (i.e.,
`
`5
`
`IBSS). Determining a required transmit power to reach nodes associated with any
`
`of the selected path gains. Selecting the minimum of the highest transmit power
`
`and allowed transmit power, wherein the allowed transmit power is determined by
`
`regulatory requirements and stations transmit power capabilities. Assigning the
`
`selected transmit power to Request To Send (RTS), Clear To Send (CTS)
`
`10
`
`messages and other frames destined for nodes associated with any of the selected
`
`path gains.
`
`In accordance with another exemplary embodiment of the invention,
`
`a method for open loop group transmit power control in an infrastructure system
`
`(i.e., a BSS or Basic Service Set), includes the following steps. Selecting, by an
`
`15
`
`access point (AP), at least one station within a group. Transmitting a transmit
`
`power information request from an AP to the at least one selected stations.
`
`Transmitting a transmit power response with transmit power information for the
`
`corresponding frame to any proximate station from the at least one selected
`
`stations in an orderly manner preventing collisions. Receiving the frame with the
`
`20
`
`transmit power response and determining the path gain based on measured signal
`
`strength of the received frame and respective transmit power information in the
`
`received frame. Selecting path gains originating from the same group (i.e., BSS).
`
`Determining required transmit power to reach nodes associated with any of the
`
`selected path gains. Selecting the minimum of the highest transmit power and
`
`25
`
`allowed transmit power, wherein the allowed transmit power is determined by
`
`regulatory requirements and stations transmit power capabilities. Assigning the
`
`selected transmit power to Request To Send (RTS), Clear To Send (CTS)
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 9 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-9-
`
`messages and other frames destined for nodes associated with any of the selected
`
`path gains.
`
`In accordance with another exemplary embodiment of the invention,
`
`a method of tiered transmit power includes the steps of determining a sequence of
`
`5
`
`frames that must be exchanged for successful communication, and assigning
`
`different transmit power levels to those frames wherein the frames have different
`
`topological objectives or distance objectives.
`
`In accordance with another exemplary embodiment of the invention,
`
`a method for interference mitigation based on open loop transmit power control
`
`10
`
`enabling tighter medium reuse, includes the following steps. Conveying transmit
`
`power control information for and in every transmitted frame by any station
`
`transmitting. Receiving frames and determining a path gain based on measured
`
`signal strength of the received frames and respective transmit power information
`
`conveyed by the received frames. Determining the maximum instantaneously
`
`15
`
`allowed transmit power based on all overheard frames such that ongoing
`
`communication is not noticeably disturbed. Conditioning transmit power, and if
`
`feasible and necessary, reducing transmit power and other transmit parameters
`
`(e.g., link rate etc), to ensure that the maximum transmit power condition is not
`
`exceeded during any transmission attempt.
`
`20
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Other objects and advantages of the present invention will become
`
`apparent to those skilled in the art from the following detailed description of
`
`preferred embodiments, when read in conjunction with the accompanying
`
`drawings wherein like elements have been designated with like reference numerals
`
`25
`
`and wherein:
`
`Figures lA-1D show an RTS-CTS-DATA-ACK message exchange.
`
`Figure 2 shows exemplary MAC Frame formats of IEEE 802.11.
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 10 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-10-
`
`Figure 3 shows NA V setting together with RTS-CTS.
`
`Figure 4 shows NA V setting when fragmentation is employed
`
`together with RTS-CTS.
`
`Figure 5 shows two sources or originating stations/nodes attempting
`
`5
`
`to access the same channel in IEEE 802. lla.
`
`Figure 6 shows an example of a Tiered TPC in an IBSS-like system
`
`in accordance with exemplary embodiments of the invention.
`
`Figure 7 shows an example of Joint TPC and LA on DATA with an
`
`optional extension to ACK in accordance with exemplary embodiments of the
`
`10
`
`invention.
`
`Figure 8 shows TPC information derived from a BEACON in IBSS
`
`in accordance with exemplary embodiments of the invention.
`
`Figures 9A and 9B show IBSS path gain estimates from a BEACON
`
`in accordance with exemplary embodiments of the invention.
`
`15
`
`Figure 10 shows a Request for TP Information issued by an AP and
`
`responded to by an addressed station in accordance with exemplary embodiments
`
`of the invention.
`
`Figure 11 shows an example of BSS TP _ Request, TP _ Reply
`
`exchange that establishes path-gain knowledge in accordance with exemplary
`
`20
`
`embodiments of the invention.
`
`Figure 12 shows exemplary TP _ Request and TP _ Reply IEs in
`
`accordance with exemplary embodiments of the invention.
`
`Figure 13 shows concurrent and adjacent DATA transmissions
`
`enabled by TPC in accordance with exemplary embodiments of the invention.
`
`25
`
`Figure 14 shows an interference profile at a receiving station in
`
`accordance with exemplary embodiments of the invention.
`
`Figure 15 shows exemplary frame formats including Closed Loop
`
`TPC and LA in accordance with exemplary embodiments of the invention.
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 11 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-11-
`
`Figure 16 shows exemplary frame formats including TP Information
`
`fields in accordance with exemplary embodiments of the invention.
`
`Figure 17 shows a frame format including a generic field for TP
`
`and LA information in accordance with exemplary embodiments of the invention.
`
`5
`
`Figure 18 shows a table describing a TPC policy following a tiered
`
`approach in accordance with exemplary embodiments of the invention.
`
`Figure 19 shows a Transmit Power Information Request Element
`
`format in accordance with exemplary embodiments of the invention.
`
`Figure 20 shows a Transmit Power Information Element format in
`
`10
`
`accordance with exemplary embodiments of the invention.
`
`Figure 21 shows BEACON modifications in accordance with
`
`exemplary embodiments of the invention.
`
`Figure 22 shows Probe Request modifications in accordance with
`
`exemplary embodiments of the invention.
`
`15
`
`Figure 23 shows Probe Response modifications in accordance with
`
`exemplary embodiments of the invention.
`
`Figure 24 shows a P TX Request format in accordance with
`
`exemplary embodiments of the invention.
`
`DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
`
`20
`
`European Regulatory requirements for the "5 GHz band" defined by
`
`ERC (European Radiocommunications Committee), limits the mean EIRP
`
`(Effective Isotropically Radiated Power) to 200 mW and 1 W, in the 5150-5350
`
`MHz (indoor) and the 5470-5725 MHz (indoor and outdoor) band respectively.
`
`Further, DFS (Distributed Frequency Selection) shall be applied over both bands
`
`25
`
`in conjunction with TPC (Transmit Power Control), the latter operating both in
`
`down- and uplink. IEEE 802.11 devices operating in the ERC area must therefore
`
`comply with stated conditions. As the IEEE 802.11 standard currently does not
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 12 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-12-
`
`incorporate the required TPC mechanisms, it is an objective of exemplary
`
`embodiments of the present invention to present methods with respect to TPC,
`
`such that ERC directives can be fulfilled. In doing so, it is a further objective of
`
`exemplary embodiments of the present invention to provide TPC methods enabling
`
`5
`
`link and system performance enhancements.
`
`Exemplary embodiments of the present invention can be applied in
`
`both infrastructure-based 802.11 WLANs with an AP (Access Point), or
`
`Infrastructure BSS (Basic Service Set), as well as ad hoc-oriented 802.11
`
`networks, or independent BSS (IBSS). DCF (Distributed Coordination Function)
`
`10
`
`has often been the preferred mode of operation as well as the fundamental channel
`
`access mode of 802.11. Against that background, a TPC scheme taking the DCF
`
`mode as a starting point is consistent with exemplary embodiments of the
`
`invention. Exemplary embodiments of the present invention can be extended or
`
`implemented to support the (E)PCF (Point Coordination Function) or the HCF
`
`15
`
`(Hybrid Coordination Function) mode.
`
`Exemplary embodiments of the present invention enable not just
`
`compliance with ERC requirements, but also enable significant enhancement of
`
`system performance in terms of throughput, delay and prolonged battery life.
`
`Exemplary embodiments of the present invention also provide mechanisms and
`
`20
`
`procedures to implicitly enhance experienced QoS (Quality of Service) as well as
`
`reduce the need for overlap BSS handling. In accordance with exemplary
`
`embodiments of the invention, TPC for IEEE 802 .11 is proposed with some
`
`modification in the current 802.11 MAC specification that may be incorporated as
`
`part of the changes within the 802.1 le framework.
`
`25
`
`In accordance with exemplary embodiments of the invention,
`
`methods, protocols and frame structures are disclosed that enable both joint and
`
`independent TPC and LA (Link Adaptation) in conjunction with a RTS/CTS based
`
`channel access scheme. In accordance with exemplary embodiments of the
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 13 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-13-
`
`invention, mechanisms are provided to differentiate TPC depending on topological
`
`goals. In an exemplary embodiment of the invention, Group based TPC
`
`mechanisms for frames like RTS and CTS are provided. Note that the term
`
`"group" is synonymous with the collection of all stations in a BSS or in an IBSS,
`
`5
`
`but can also be interpreted in other groupings not specified by or explicitly defined
`
`in IEEE 802.11. Exemplary embodiments of the present invention also provide a
`
`TPC mechanism for interference mitigation, such that stations belonging to other
`
`Groups (BSSs or IBSSs, where "BSS" stands for Basic Service Set and "IBSS"
`
`stands for Independent Basic Service Set) are not interfered with. At the same
`
`10
`
`time this enables reuse of the channel provided a suitable TP (Transmit Power)
`
`level is selected. Interference mitigation mechanisms may alternatively be
`
`employed within a group, e.g., an infinite large and dispersed group. In
`
`accordance with exemplary embodiments of the present invention, as a basis for
`
`those mechanisms, both closed loop as well as open loop TPC are applied.
`
`15
`
`In reducing generated interference and minimizing power
`
`consumption, it is vital to apply the most aggressive and precise TPC scheme to
`
`the bulk traffic of the network, most likely consisting of DATA (and ACK)
`
`frames. Next to DATA frames, the RTS and CTS frames may, depending on the
`
`adotllThreshold value, be relatively prevalent and hence considered as important
`
`20
`
`contributors to undesired interference and power c,onsumption. As RTS and CTS
`
`frames in general are shorter than DATA frames, their supplement to the overall
`
`average interference picture will accordingly also be lower. Frames occurring
`
`merely occasionally, such as Beacons, have even lesser impact on the average
`
`interference situation. In addition, of diminishing the radiated average
`
`25
`
`interference level, the issue of minimizing peak interference and associated
`
`variations is also of interest. Different traffic conditions may alter assumptions
`
`above, but the given statements are believed to be true in most if not all relevant
`
`scenarios. Those issues together with the objectives set forth earlier motivate the
`
`Hewlett Packard Enterprise Co. Ex. 1007, Page 14 of 64
`Hewlett Packard Enterprise Co. v. Intellectual Ventures II LLC
`IPR2021-01376
`
`

`

`WO 02/082751
`
`PCT /SE02/00706
`
`-14-
`
`following two items. First, a so-called TPC policy to be defined, giving very
`
`rough guidelines on TP algorithmic goals. Second, a TPC mechanism to be
`
`defined, designed to support the TPC policies.
`
`One aspect of the invention is to enable a tiered TPC policy in a
`
`5
`
`CTS/RTS based channel access system. The motivation for this is that different
`
`topological and communication range aspects need to be met depending on frame
`
`type. Note that those frames, as the one in IEEE 802.11, have a timely and
`
`logical relation to each other. In accordance with exemplary embodiments of the
`
`invention, the TPC policy follows a tiered approach defining three levels. Frames
`
`10
`
`with different topological destination objectives are divided among those three
`
`Tier-classes. Figure 18 shows the three major TPC tiers.
`
`As Tier 1 frames are sent with high transmit power, this class also
`
`adopts a policy of being constrained in time. The reason is to minimize random
`
`interference peaks within and towards neighboring (I)BSS. This may be achieved
`
`15
`
`by confining Tier 1 traffic around Beacon transmit occasions, i.e. sent regularly
`
`around TBTT (Target Beacon Transmission Time).
`
`In Tier 1, Beacon TPC, the BEACON frame as defined in the IEEE
`
`802 .11-1999 standard, and other conceivable frames/messages with similar
`
`topological destination purposes, must generally reach as far as possible.
`
`20
`
`However, those