(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2005/0003827 A1
`(43) Pub. Date:
`Jan. 6, 2005
`Whelan
`
`US 20050003827A1
`
`(54) CHANNEL, CODING AND POWER
`MANAGEMENT FOR WIRELESS LOCAL
`AREANETWORKS
`
`(76) Inventor: Robert J. Whelan, Kirkland, WA (US)
`Correspondence Address:
`JONES DAY
`222 EAST 41ST ST
`NEW YORK, NY 10017 (US)
`(21) Appl. No.:
`10/778,758
`(22) Filed:
`Feb. 13, 2004
`
`Related U.S. Application Data
`(60) Provisional application No. 60/447,166, filed on Feb.
`13, 2003.
`
`Publication Classification
`
`(51) Int. Cl." ....................................................... H04Q 7/20
`(52) U.S. Cl. .............................................................. 455/454
`(57)
`ABSTRACT
`A System and method are disclosed for the management of
`WLANS in cases where unmanaged access points are
`present as well as with the addition or removal of acceSS
`points. The disclosed System and method use Signal data and
`network traffic statistics collected by mobile units to deter
`mine optimal configuration Settings for the access points.
`The access point Settings So managed can include the
`operating channel or center frequency, orthogonal Signal
`coding used (optionally including the data rate), if any, and
`the transmission power. The Solutions computed can account
`for the inherent trade-offs between wireless network cover
`age area and mutual interference that may arises when two
`or more access points use the same or overlapping frequency
`bands or channels and the same or Similar Signal coding.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Collect mobile unit signal
`strength measurements.
`
`100
`
`Censor measurements from
`overlapping signals.
`
`O2
`
`Correct signal measurements by
`access point power level.
`
`104
`
`Filter signals out of relevant
`strength range
`
`ldentify measurements with
`similar signal strength from two
`or more access points
`
`
`
`
`
`108
`
`Determine propagation path
`based distances
`
`10
`
`Classify neighbor relationships
`
`14
`
`ldentify minimum RSS
`measurements
`
`6
`
`Hewlett Packard Exhibit 1007, Page 1 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 1 of 28
`
`US 2005/0003827 A1
`
`
`
`Hewlett Packard Exhibit 1007, Page 2 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 2 of 28
`
`US 2005/0003827 A1
`
`1-0 I
`
`9e IOIII
`
`Hewlett Packard Exhibit 1007, Page 3 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 3 of 28
`
`US 2005/0003827 A1
`
`%09%0#7%09%0Z
`
`
`
`ºleh med pou?usueII
`
`
`
`er
`
`eqe induanou L
`
`Hewlett Packard Exhibit 1007, Page 4 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication
`
`Jan. 6, 2005 Sheet 4 of 28
`
`US 2005/0003827 A1
`
`
`
`Hewlett Packard Exhibit 1007, Page 5 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 5 of 28
`
`US 2005/0003827 A1
`
`
`
`Axial line between
`access points
`
`Transverse line
`
`------------------
`
`Figure 5A. Signal environment between access points
`
`Hewlett Packard Exhibit 1007, Page 6 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 6 of 28
`
`US 2005/0003827 A1
`
`Figure 5B. RSS vs. Distance from AP 1
`(m)
`
`20
`
`30
`
`40
`
`50
`
`60
`
`70
`
`80
`
`RSSI from AP 1
`
`RSSI from AP2 -
`1.
`1.
`1.
`
`a
`
`Distance
`
`3
`
`Figure 5C. RSS vs. distance from axial line (m)
`9
`& S
`S
`
`d O O O
`w
`co
`cN
`
`Cd
`
`-40
`-41
`-42
`-43
`-44
`-45
`-46
`-47
`-48
`-49
`-50
`-51
`
`RSSI from
`
`1 or AP 2
`
`Distance from centerline
`
`
`
`Hewlett Packard Exhibit 1007, Page 7 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication
`
`Jan. 6, 2005 Sheet 7 of 28
`
`US 2005/0003827 A1
`
`
`
`Hewlett Packard Exhibit 1007, Page 8 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 8 of 28
`
`US 2005/0003827 A1
`
`r
`
`s () Ac Y
`
`c
`
`--
`
`---- ée
`
`s
`
`M
`M
`
`V
`
`I
`
`3
`N
`
`V
`\%.
`V
`
`r
`
`5 /
`/
`/
`
`N
`N
`N
`N
`
`V
`V
`
`|-
`f
`
`
`
`E g
`.
`S
`
`5. M
`s
`
`Hewlett Packard Exhibit 1007, Page 9 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 9 of 28
`
`US 2005/0003827 A1
`
`
`
`
`
`
`
`Hewlett Packard Exhibit 1007, Page 10 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 10 of 28
`
`US 2005/0003827 A1
`
`Collect mobile unit signal
`strength measurements
`
`Censor measurements from
`Overlapping signals.
`
`10
`O
`
`l
`
`O2
`
`Correct signal measurements by
`access point power level.
`
`104
`
`Filter signals out of relevant
`strength range.
`
`106
`
`
`
`
`
`identify measurements with
`similar signal strength from two
`or more access points
`
`
`
`108
`
`Determine propagation path
`based distances
`
`10
`
`Classify neighbor relationships
`
`14
`
`ldentify minimum RSS
`meaSurements
`
`6
`
`Figure 7A. Simplified Process Flow
`
`Hewlett Packard Exhibit 1007, Page 11 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 11 of 28
`
`US 2005/0003827 A1
`
`Sort minimum RSS
`measurements by neighborhood 118
`
`Determine most constrained
`access point.
`
`
`
`
`
`se- Apply tie breaking condition
`
`126
`
`N O
`
`124
`
`Assign Channel for first access 128
`point.
`
`.
`
`Assign Codes for first access
`point.
`
`30 - -
`-
`
`-
`
`.
`
`-
`.
`
`
`
`Determine most constrained
`neighboring access point.
`
`No
`
`34
`
`
`
`Determine assigned channels
`used by nearest neighbors.
`
`138
`
`Apply tie breaking condition
`
`136
`
`Figure 7B. Simplified Process Flow
`
`Hewlett Packard Exhibit 1007, Page 12 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 12 of 28
`
`US 2005/0003827 A1
`
`
`
`
`
`
`
`Change Channels?
`
`Are free channels available?
`
`
`
`
`
`
`
`
`
`
`
`
`
`Apply tie breaking
`condition
`
`
`
`
`
`Assign channel.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`l62
`Figure 7C. Simplified Process Flow
`
`Assign channel.
`
`Determine neighbor channel
`assignment of near access
`point
`
`Rank neighbors by
`Constraints and probability of
`packet collision.
`
`No
`Select next access point on
`list.
`
`Are free channels
`available?
`
`Other access points?
`
`
`
`Assign channel to channel of
`neighbor at greatest distance
`and lowest probability of mutual
`interference
`
`Hewlett Packard Exhibit 1007, Page 13 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 13 of 28
`
`US 2005/0003827 A1
`
`
`
`Determine assigned codes used 170
`by neighbors on same channel.
`
`Change code?
`
`NO
`
`Yes
`
`172
`
`
`
`Are free codes?
`
`. No
`
`YeS
`
`174
`
`Figure 7D. Simplified Process Flow
`
`Hewlett Packard Exhibit 1007, Page 14 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 14 of 28
`
`US 2005/0003827 A1
`
`
`
`
`
`
`
`Determine neighbor code
`assignment of near access point 180
`
`Rank neighbors by constraints
`and probability of packet
`Collision.
`
`182
`
`
`
`<> Condition
`
`184
`
`Apply tie breaking
`
`186
`
`
`
`
`
`Select access point from list.
`
`188
`
`Are free codes available?
`
`Yes
`
`Other access points?
`
`
`
`Assign code to code of neighbor
`with lowest signal strength ratio
`and lowest probability of mutual
`interference
`
`196
`
`Figure 7E. Simplified Process Flow
`
`Hewlett Packard Exhibit 1007, Page 15 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 15 of 28
`
`US 2005/0003827 A1
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`204
`
`Other access points?
`
`Y e-C c D
`
`200
`No
`Estimate mutual interference
`based on channel and code
`assignments and traffic levels.
`
`202
`
`Determine Constraints from
`mutual interference estimates 203
`
`Rank neighbors by constraints
`and probability of packet
`
`Collision.
`
`.
`
`
`
`208
`
`Apply tie breaking
`Condition
`
`206
`
`Select access point from list.
`
`210
`
`Figure 7F. Simplified Process Flow
`
`Hewlett Packard Exhibit 1007, Page 16 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 16 of 28
`
`US 2005/0003827 A1
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Change power level?
`
`Apply coverage constraints.
`
`Change power level.
`
`Other access points?
`
`Are there access
`points not meeting the coverage
`area requirements?
`
`No
`
`
`
`1 Are there access
`points anticipating excessive
`mutual interference?
`
`224
`
`Figure 7G. Simplified Process Flow
`
`Hewlett Packard Exhibit 1007, Page 17 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 17 of 28
`
`US 2005/0003827 A1
`
`ply tie breaking
`Condition
`
`230
`
`
`
`Rank neighbors by constraints
`and probability of packet
`Collision.
`
`
`
`
`
`226 sce 228
`
`Select first access point on list. 232
`
`Compute maximum uSable data 234
`rate. .
`
`
`
`
`
`-
`Other access points?
`
`Yes
`
`No
`
`236
`
`Transmit channel, code, data
`rate, and power settings to
`access points
`
`238
`
`End
`
`Figure 7H. Simplified Process Flow
`
`Hewlett Packard Exhibit 1007, Page 18 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 18 of 28
`
`US 2005/0003827 A1
`
`
`
`
`
`//
`
`
`
`8
`
`Hewlett Packard Exhibit 1007, Page 19 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication
`
`Jan. 6, 2005 Sheet 19 of 28
`
`US 2005/0003827 A1
`
`8 I
`
`
`
`
`
`Hewlett Packard Exhibit 1007, Page 20 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication
`
`Jan. 6, 2005 Sheet 20 of 28
`
`US 2005/0003827 A1
`
`
`
`
`
`
`
`
`
`
`
`
`
`Hewlett Packard Exhibit 1007, Page 21 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication
`
`Jan. 6, 2005 Sheet 21 of 28
`
`US 2005/0003827 A1
`
`
`
`º
`
`
`eeuw afielenoo
`ººººººººººººººººº
`
`?????????
`
`Hewlett Packard Exhibit 1007, Page 22 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication
`
`Jan. 6, 2005 Sheet 22 of 28
`
`US 2005/0003827 A1
`
`
`
`
`
`9I0EI q.}{AA 33b.19A0O qu?oq ss333 V ‘ZI 9.InáH
`
`
`
`
`
`
`
`Y.
`
`X
`s
`s
`
`s'
`
`X
`
`d
`
`8
`I
`
`
`
`8INgeºfy efferenoo
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Hewlett Packard Exhibit 1007, Page 23 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication
`
`Jan. 6, 2005 Sheet 23 of 28
`
`US 2005/0003827 A1
`
`
`
`?IM eeuw
`
`OU
`
`36eJæNOO
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Hewlett Packard Exhibit 1007, Page 24 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Hewlett Packard Exhibit 1007, Page 25 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication
`
`Jan. 6, 2005 Sheet 25 of 28
`
`US 2005/0003827 A1
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`ha
`
`s
`As
`
`O
`
`d
`
`s
`
`
`
`OO
`
`8
`
`Hewlett Packard Exhibit 1007, Page 26 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Hewlett Packard Exhibit 1007, Page 27 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Hewlett Packard Exhibit 1007, Page 28 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`Patent Application Publication Jan. 6, 2005 Sheet 28 of 28
`
`US 2005/0003827 A1
`
`S
`
`&
`
`S
`
`
`
`CN
`C
`
`r
`Od
`
`S
`
`Hewlett Packard Exhibit 1007, Page 29 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`US 2005/0003827 A1
`
`Jan. 6, 2005
`
`CHANNEL CODING AND POWER
`MANAGEMENT FOR WIRELESS LOCALAREA
`NETWORKS
`
`FIELD OF THE INVENTION
`0001) This application relates to the field of Wireless
`Local Area Network (WLAN) network management.
`
`BACKGROUND
`0002. In a WLAN, one or more base stations or access
`points (AP) bridge between a wired network and radio
`frequency or infrared connections to one or more mobile
`stations or Mobile Units (MU). The MUs can be any of a
`wide variety of devices including, laptop computers, per
`Sonal digital assistants, wireleSS bar code Scanners, wireleSS
`point of Sale Systems or payment terminals, and many other
`specialized devices. Most WLAN systems used in business
`and public access environments adhere to the IEEE 802.11
`specifications. Other WLANS are based on other wireless
`technologies including, the Specifications promulgated by
`the Bluetooth Special Interest Group, proprietary radio fre
`quency protocols and infrared-link protocols.
`0003 Wireless Local Area Networks (WLANs) are now
`in common use in both large and Small businesses, as public
`Internet acceSS points, and in home environments. Millions
`of base-stations or access points and mobile units are now
`deployed. AcceSS points and base Stations are understood
`here to include implementations with more than one central
`frequencies and more than one antennas. This increasing
`density of access points creates additional network manage
`ment problems. Specifically access points using the same or
`overlapping frequency bands or channels and the same or
`Similar signal coding have the potential to create mutual
`interference. Mutual interference leads to packet collisions,
`the need to retransmit packets, potentially reducing network
`throughput. At the same time, the coverage area of the acceSS
`points may not be Sufficient, leading to poor Signal quality
`at the edges of the network or “coverage holes'.
`0004 Conventional approaches to the optimization of
`wireleSS networks involve making Surveys of the desired
`coverage area. The results of these Surveys are then used to
`determine the optimum Settings for channel Selection, Signal
`coding and power for the access points.
`0005 Attempts may also be made to determine if existing
`access points should be moved to other locations or new
`access points added to the wireleSS network. Survey
`approaches Suffer from Several difficulties including:
`0006 1. It is usually quite expensive to collect and
`analyze the data.
`0007 2. The survey data is static. Thus, if conditions
`change within the area of interest the Survey would need to
`be run once again or the design of the wireleSS network
`would be less than optimal.
`0008. 3. The equipment used to make the Survey typically
`has fixed and distinctive physical properties (antennas,
`receivers, Velocity of travel, etc.). In practice, mobile units
`will have different physical properties and will therefore
`experience wireleSS network quality that is different from the
`Survey equipment.
`
`0009. Other approaches to management of wireless net
`WorkS can involve the collection of Signal measurements by
`access points. In these Schemes, the wireleSS network man
`agement System uses Signal information collected by the
`access points as a basis to adjust the channel assignments,
`Signal coding assignments and power levels, in attempts to
`optimize network performance. In most cases the access
`points collect information on the Signals broadcast by the
`other acceSS points. These Schemes Suffer from a number of
`drawbacks including:
`0010) 1. The access points can only take measure
`ments at fixed locations,
`0011) 2. The receiver and antenna properties of the
`access point can be quite different from those of the
`mobile units;
`0012. 3. The transmission power levels of the access
`points and mobile units may be quite different; and,
`0013 4. The possible use of diversity antennas in
`access points, but not in mobile units.
`0014 5. Each single access point only has local
`knowledge of the environment and is thus, unlikely
`to make changes that are globally optimal.
`
`SUMMARY
`0015 The channel, coding and power management sys
`tem described overcomes the deficiencies of prior art power,
`coding and channel management Systems through a simpli
`fied approach using data collected from mobile units to
`optimize the performance of the network. The System pro
`vides for the management of WLANs in cases where unman
`aged access points are present. Further, the System can
`provide information on the possible need to add acceSS
`points.
`0016. The disclosed channel, coding and power manage
`ment System uses Signal data and network traffic Statistics
`collected by the mobile units to determine optimal configu
`ration Settings for the access points. The access point Set
`tings managed by the System can include the operating
`channel or center frequency, orthogonal Signal coding used,
`if any, and the transmission power. In Some embodiments,
`Signal coding can include the data rate used by the mobile
`units and the access points, which may also be controlled.
`The Solutions computed can account for the inherent trade
`offs between wireleSS network coverage area and mutual
`interference. Mutual interference arises when two or more
`access points use the same or overlapping frequency bands
`or channels and the same or Similar Signal coding. These
`Situations can arise as a result of the often-limited choice
`available of channels and orthogonal codes. Higher levels of
`mutual interference can lead to low network data through
`put. On the other hand, reasonable acceSS point transmission
`power must be maintained to achieve coverage of the
`desired areas.
`0017. Any device can perform the collection and report
`ing of radio frequency signal data if it has the required
`receiver, Signal measurement capabilities and any type of
`data connection to data repository. In the following discus
`Sion, these devices will be referred to has “mobile units', but
`can in fact include a number of other types of devices
`including:
`
`Hewlett Packard Exhibit 1007, Page 30 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`US 2005/0003827 A1
`
`Jan. 6, 2005
`
`1. The device may be any type of general-purpose
`0.018
`computer, for which the main purpose is not to collect data,
`but rather collects data and reports in available idle time.
`0.019
`2. The device used for data collection may not
`require any special purpose hardware or driver Software, but
`may only use Standard configurations.
`0020 3. The device may or may not move with time.
`0021 4. The device may be dedicated to the collection of
`radio signal data at a fixed location or moving between
`Several locations with time.
`0022 5. May have one or more additional network inter
`faces, Some of which may connect to wired networks or
`other wireleSS networkS.
`0023 The computations of the channel, coding, and
`power management System can determine neighbor relation
`ships between access points without the need for geographic
`location data. In Some embodiments, the System uses signal
`Strength relationships between access points to determine
`the relative distances. These distances are then used to
`determine neighbor relationships between the access points.
`These neighbor relationships are, thus, based on radio fre
`quency propagation or path loSS relations, and may more
`accurately define the coverage areas of the access points and
`the potential for mutual interference when compared to the
`geometric relationships of geographically defined models. In
`Some alternative embodiments, geographic location of the
`access points can be used to determine neighbor relation
`ships. In yet other alternative embodiments, geographic
`location of the acceSS points, along with Signal Strength
`measurements from the mobile units, can be used to deter
`mine neighbor relationships.
`0024.
`In some embodiments, the mobile units will expe
`rience Signal interference from unmanaged access points or
`other Sources of in-band radio frequency energy. The acceSS
`point Settings determined by the System can account for
`these Sources. Typically, Signal Strength information and
`neighbor relationships are used in these computations.
`0.025 The same data collected by the mobile units can be
`used to report on and possibly respond to the State of
`network performance. System administrators use the SyS
`tem's reporting capabilities to determine if the network is
`operating properly, to review automatically computed acceSS
`point Setting changes, and if required perform manual Set
`tings. Thus, the System can accommodate a mixture of
`automatic and manual control and reporting techniques.
`0.026
`Signal data and traffic statistics collected by the
`mobile units can be Subject to considerable variation or
`fluctuations. These variations or fluctuations arise from a
`number of Sources, including multi-path Signal propagation,
`variations in mobile unit characteristics, time dependant
`changes in the network environment, and different travel
`paths used by the different mobile units. The limited
`dynamic range and noise characteristics of the mobile unit
`receivers can also contribute to fluctuations or variations in
`Signal measurements. Additional variation can arise for the
`
`use of different access point characteristics and transmission
`power levels. In Some embodiments, the data collected by
`the mobile units is preprocessed by a number of techniques,
`including censoring, combining, and power correction.
`0027. In some embodiments, the rate at which access
`point Settings are updated can be adjusted. These time
`dependent parameters allow the System to compute stable
`Solutions, based on the long-term behavior of the network.
`If these time constants are too short, the Settings may change
`in response to inconsequential changes in network measure
`ments (i.e. variations in traffic volume), which can lead to
`unstable behavior or oscillations. If these time constants are
`too long, the access point Settings may not change rapidly
`enough to respond effectively to changes in the network
`environment. Some embodiments incorporate parameters
`controlling the rate of changes in access point Settings when
`a known change has been made to the network. Examples of
`known changes to the network include, the failure of an
`access point, the addition of a managed access point, and the
`removal of a managed access point.
`0028. In some embodiments, the channel, code and
`power management System can control the operation of
`redundant access points. If redundant access points are
`maintained in an online State, the result can be increased
`mutual interference and reduced network throughput as a
`result of having multiple access points with redundant
`coverage areas using a limited Set of channels and Orthogo
`nal Signal codes. To overcome these difficulties, but still
`allow for redundancy and high-availability, Some embodi
`ments of the power, channel and code management System
`include the capabilities to manage redundant acceSS points in
`an offline configuration and only bring them online when
`required.
`0029 Depending on the details of the embodiment, the
`channel, code and power management System can apply to
`a variety of (often approximate) Solution algorithms to the
`computation of optimal access point Settings. A given Solu
`tion technique can attempt to find the local (with respect to
`neighbors) Solution for an access point's channel, signal
`coding and power Settings. In other cases the Solution can
`determine a globally optimum Solution. In Some embodi
`ments an iterative or Stepwise Solution considering the local
`neighborhood for a given access point is applied. In other
`embodiments these Solution iterative techniques are used to
`compute globally optimized Solutions. Some other alterna
`tive embodiments can apply linear or nonlinear optimization
`techniques to the computation of a Solution. In yet other
`alternative embodiments, evolutionary Solution techniques
`can be used to compute local, or global Solutions.
`0030. It will be appreciated that the foregoing statements
`of the features of the invention are not intended as exhaus
`tive or limiting, the proper Scope thereof being appreciated
`by reference to this entire disclosure and to the Substance of
`the claims.
`0031. It will be understood that while the discussions
`contained in this document refer Specifically to local area
`wireless networks with fixed base stations, it will be under
`stood that the ideas discussed are equally applicable to wide
`area wireleSS networks and peer-to-peer wireleSS networks
`without fixed access points or base Stations.
`
`Hewlett Packard Exhibit 1007, Page 31 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`US 2005/0003827 A1
`
`Jan. 6, 2005
`
`BRIEF DESCRIPTION OF FIGURES
`0032) The invention will be described by reference to the
`preferred and alternative embodiments thereof in conjunc
`tion with the drawings in which:
`0.033
`FIG. 1 is a simplified diagram showing signal
`Strength measurements by mobile units,
`0034 FIG. 2 is a hypothetical bit error rate curve for a
`mobile unit receiver;
`0.035
`FIG. 3 is an example of network throughput versus
`Submitted data;
`FIG. 4 is a simplified overall system block dia
`0036)
`gram,
`0037 FIGS.5A, 5B, and 5C is a simplified diagram of a
`technique to determine propagation distance between acceSS
`points;
`0038 FIGS. 6A, 6B, and 6C is a diagram showing a
`Simplified example of acceSS point configuration;
`0039 FIG. 7A, 7B, 7C, 7D, 7E, 7F, 7G and 7H is a
`Simplified process flow diagram;
`0040 FIG. 8 is an example of access point coverage with
`mutual interference;
`0041 FIG. 9 is an example of access point coverage with
`reduced mutual interference;
`0.042
`FIG. 10 is an example of access point coverage
`with mutual interference;
`0.043
`FIG. 11 is an example of access point coverage
`with reduced mutual interference;
`0044 FIG. 12 is an example of access point coverage
`with a hole;
`004.5
`FIG. 13 is an example of expanded access point
`cOVerage,
`0.046
`FIG. 14 is an example of access point coverage
`with a new acceSS point,
`0047 FIG. 15 is an example of access point coverage
`with an offline acceSS point,
`0.048
`FIG. 16 is an example of access point coverage
`with increased power;
`0049 FIG. 17 is an example of access point coverage
`with overlap, and,
`0050 FIG. 18 illustrates an example of an access point
`configuration with redundancy.
`
`DETAILED DESCRIPTION OF EMBODIMENTS
`0051. The following detailed description refers to the
`accompanying drawings, and describes exemplary embodi
`ments of the present invention. Other embodiments are
`possible and modifications may be made to the exemplary
`embodiments without departing from the Spirit, functionality
`and scope of the invention. Therefore, the following detailed
`descriptions are not meant to limit the invention.
`
`0.052 Overview of the Embodiments
`0053 To maximize performance and throughput of wire
`leSS networks, the mutual interference from the base-stations
`or acceSS points experienced by the mobile units must be
`minimized.
`0054 Mutual interference arises when two or more
`access points use the same or overlapping frequency bands
`or channels and the same or Similar signal coding. While it
`is desirable to reduce mutual interference, at the same time,
`the coverage area of the wireleSS network must be main
`tained. Thus, the Selection of channels, the Selection of
`Signal coding and the Setting of power levels for the access
`points must balance the competing desires to maximize
`coverage area while minimizing mutual interference.
`0055. The maximization of coverage area and minimiza
`tion of mutual interference is made more complicated by
`both the complex real-world propagation environment and
`the fact that different mobile units have differing receiver
`and antenna characteristics. Thus, a wireleSS network opti
`mized for one type of mobile unit applied to a particular
`range of applications may not optimal for another type of
`mobile unit applied to another range of applications. A wide
`range of factors can affect how a given mobile unit experi
`ences the quality of a wireleSS network including:
`0056 1. The type of antenna or antennas used;
`0057 2. Velocity of travel and hence signal fading
`environment;
`0058. 3. The possible use of antenna diversity tech
`niques,
`0059 4. Polarization of antennas;
`0060 5. The types of modulation and signal coding;
`and,
`0061 6. The presence or absence of wave scattering
`and obstructing objects giving rise to Signal Shad
`owing and multi-path propagation.
`0062 Another complicating factor is the presence of
`unmanaged acceSS points or other Sources of radio frequency
`energy. An unmanaged acceSS point can be any access point
`in or near the coverage area of interest. These unmanaged
`access points and Sources of radio frequency energy can
`include:
`0063 1. Access points that belong to the organiza
`tion managing the wireleSS network, but lacking the
`properties required to control any one or all of power,
`channel Selection, and coding;
`0064. 2. Access points under the control of other
`organizations but in the general area of the wireleSS
`network being managed;
`0065 3. Other radio services sharing the same spec
`trum, including remote control devices, cordless
`telephones, and data devices using other communi
`cations protocols and Standards (e.g., Bluetooth VS.
`IEEE 802.11 standards); and,
`0066 4. Other sources of broadband interference
`including, electric motors and other electrical equip
`ment, and electronic devices.
`
`Hewlett Packard Exhibit 1007, Page 32 of 54
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`US 2005/0003827 A1
`
`Jan. 6, 2005
`
`0067. The complex environment affecting the quality of
`the wireless network is further complicated by the fact that
`the environment and even the properties of the mobile units
`themselves can dynamically change in time. It is not unusual
`for the physical environment to change. For example, con
`Struction can add or remove obstacles or objects Scattering
`and Shadowing Signals. Managed access points may be
`moved over time for any number of reasons. The presence,
`absence, location or characteristics of unmanaged acceSS
`points or other Sources of radio frequency energy can change
`over time, Sometimes at a rapid rate. Finally, new types of
`mobile units are introduced, which may have different
`physical properties or may be applied in new applications
`and will therefore experience the wireleSS network environ
`ment differently.
`0068 FIG. 1 shows a simplified diagram of signal
`Strength measurements, i.e., Received Signal Strength Indi
`cator (RSSI), experienced by mobile units. The access points
`14 broadcast signals to the mobile units 16. The mobile units
`receive Signals from one more access points. In this example
`the strength of the RSSI measured by the mobile unit from
`each access point is shown by a number in the box next to
`the dotted line connecting the mobile unit to that acceSS
`point. In the example shown in FIG. 1, mobile unit MU2
`receives relatively strong Signals from acceSS points AP1
`and AP2, and receives a weaker Signal from AP3. Depending
`on the channels and Signal coding used by the mobile unit
`MU2, it may experience more or less mutual interference
`between these access points. Likewise mobile unit MU1 and
`MU3 receive signals at different strengths from the three
`access points.
`0069 FIG. 2 shows an example of the Bit Error Rate
`(BER) performance of a wireless receiver versus the Signal
`to Noise Ratio (SNR). The performance curve 30 shows the
`expected BER of the receiver over a range of SNR. If the
`SNR is too low 32, the BER of the receiver may become too
`high for the application. Therefore, it is usually advanta
`geous to design the wireless network so that the SNR is
`Sufficient