May 2000
`
`doc.: IEEE 802.11-00/123
`
`IEEE P802.11
`Wireless LANs
`An estimate of the minimum number of channels for full capacity
`54 Mbit/s 802.11a in a dense cellular structured network
`May 9, 2000
`
`Date:
`
`Author:
`
`David Skellern
`Radiata Communications Inc.
`Level 2, 1 Julius Avenue
`North Ryde, NSW 2113, Australia
`Phone: +61 2 8874 5404
`Fax: +61 2 8874 5401
`e-Mail: daves@radiata.com
`
`Abstract
`An estimate of the minimum number of channels needed to achieve full 54 Mbit/s capacity in a dense cellular
`structured 802.11a network is obtained under the assumption that the only source of interference is from cochannel
`use. More channels will be needed to achieve full capacity in any realistic situation.
`
`Introduction
`This submission draws on the results of previous work1 on co-channel interference modelling to obtain an estimate
`of the minimum number of channels needed to support the full rate of 54 Mbit/s in a dense environment of 802.11a
`networks. The method is based on modelling the dense environment as a cellular structure with an access point at
`the centre of each cell. The number of channels needed for full coverage of an area is calculated by considering the
`carrier to interference ratio constraints in the optimistic case where the only interference arises from the presence of
`cochannel cells.
`
` The number of channels, N, in this case can be shown to be given by:
`
`where
`
`N
`
`
`
`
`
`
`1
`Z
`
`
`
`1
`
`
`
`
`
`1
`
`2
`
`
`
` 
`
` 
`is the ceiling function
`is a geometry model factor equal to 2 for square cells and 3 for hexagonal cells
`
`is the strength of the interferer relative to a cochannel interferer (i.e. = 1 for a cochannel interferer)
`
`is the C/I (Carrier to Interference ratio) performance threshold (in linear form)
`Z
`is the propagation path loss exponent.
`
`An Estimate of N for the 802.11a 54 Mbit/s Mode
`Calculation of the number of channels requires the values of , Z and , all of which could be the subject of long
`debate and experiment.  is 1 under the assumption of cochannel interference only.
`
`_
`
`The theoretical value of Z for the 54 Mbit/s mode over an AWGN channel is close to 22dB. To this must be added
`some allowance for the more realistic case of a non-Gaussian channel plus an allowance for implementation loss. A
`realistic value for Z could be in the range 26 to 30dB (giving Z, as a linear ratio, in the range 398 to 1000).
`
`1 B C Jones & D J Skellern, “HIPERLAN System Performance Under DCA and FCA”, 8th IEEE International
`Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC ’97), 1–4 September 1997, Helsinki,
`Finland, pp 1216-1220. (PDF copy at http://www.ics.mq.edu.au/~brendan/phd/publications/pimrc97.pdf)
`Submission
`page 1
`David Skellern, Radiata Inc
`
`
`
`
`
`Hewlett Packard Exhibit 1015, Page 1 of 2
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`

`

`doc.: IEEE 802.11-00/123
`May 2000
`The range of values for the path loss exponent might typically be from 2 (free space loss and also the limit of an
`indoor three ray propagation model) to, say, 3.5. Note that a worse result (ie large number of channels) arises for
`lower . An average figure for outdoor use may be under 3.
`
`The value of the geometry factor depends on the environment. =2 (square cells) is likely choice for indoor use,
`while =3 may be more realistic for outdoor operation.
`
`Using these values, the minimum number of channels can be calculated to be in the range 533 (square cells, g=2,
`Z=1000) to 24 (hexagonal cells, g=3, Z=398). For a mid-range set of parameters, say, g=2.5, D=3, Z=631 (28dB),
`the number of channels needed is 68.
`
`It should be stressed that these estimates are the MINIMUM number of channels based on consideration of
`cochannel interference alone.
`
`Submission
`
`page 2
`
`David Skellern, Radiata Inc
`
`
`
`
`
`Hewlett Packard Exhibit 1015, Page 2 of 2
`Hewlett Packard Enterprise Company v. Intellectual Ventures II LLC
`IPR2021-01377
`
`