Transcript 19-04-0020-00-0000-coexistence-studies-in-licensed-bands.ppt

May 2004
doc.: IEEE 802.19-04/0020r0
Coexistence in Licensed Bands
Issues & Methodologies
IEEE 802.19 Meeting
May 2004
Joanne Wilson
Joanne@arraycomm.com
Submission
Reza Arefi
reza.arefi@ieee.org
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Status of Coexistence Studies in IEEE 802
 Unlicensed
 802.15.2 produced coexistence guidelines
 802.19 TAG was formed to address unlicensed band
coexistence between wireless 802 projects
 Licensed
 802.16.2 produced a Recommended Practice (and its
revision) to address intra-802.16 licensed band coexistence
 Very limited scope
 No definition of coexistence is provided
 802.20
 Coexistence CG was formed in July 2003
 The WG voted to hold off on Coexistence work in November
2003
Submission
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Licensed bands
 802 projects for licensed bands (802.16 and 802.20)
deal with metropolitan/wide area networks with
multi-cell deployments
 Coexistence with geographical and/or spectral
neighbors is key to successful deployments in
licensed bands
 Objective is to create guidelines for preventing from
harmful interference by determining levels of
permissible, or acceptable, interference
 Interference environment varies with deployment
scenarios
Submission
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Deployment Scenarios
 Deployments could be under nation-wide licenses
 Deployments are likely to have multiple operators
with potentially different systems :
 in the same service area
 In adjacent service areas (domestic as well as international)
 Deployments in or adjacent to bands already used for
commercial services are also likely
 Cellular, PCS, 3G, Radar, P-P links, broadcast
 No shared environment
 Co-channel in adjacent areas, or
 Adjacent channel in same area, but
 No co-channel in same area
Submission
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Specifics
 From regulatory point-of-view, licensed co-channel
operation in the same geographical area would not
be allowed
 Cognitive Radios?
 Possibilities
 Co-channel across service boundary: geographical neighbors
 Adjacent channel within same service/geographic area:
spectral neighbors
 Neighbor could be non-802.xx or same 802.xx but of a
different duplex
 It could be assumed that geographical and spectral
neighbors of the same duplex have much easier time
coexisting with each other with reasonable coordination
 frame synchronization, power at service boundary, etc.
Submission
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Spectral Neighbors, Same Area
 802.xx systems may need to coordinate with spectral
neighbors
Lower neighbor
Lower neighbor
802.xx FDD
802.xx TDD
Middle neighbor(s)
Upper neighbor
802.xx FDD
Upper neighbor
 The number and the nature of spectral neighbors
TDD and FDD systems may need to coordinate with
are not necessarily the same
Submission
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Geographical Neighbors, Same Frequency
 Service areas for licensed spectrum typically don’t
overlap, but exceptions do exist
 Protection, in Service Rules, is typically through power limit
at service boundary, which may or may not be sufficient
 Interference scenarios (general)
 Base-Base
 Sub-Sub
 Base-Sub
 Sub-Base
System
1
System
2
Blue: intended
Red: interference
Submission
Service boundary Joanne Wilson & Reza
Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
TDD-FDD Issues
 Coexisting of FDD systems (co- or adj-channel)
 Base-Sub
 Sub-Base
f
 For TDD-FDD or unsynchronized TDD-TDD case:
 Examination of Base-Base and Sub-Sub scenarios are also
required
f
 Safe distance needs to be determined
Submission
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Service Rules
 For each band, out-of-band emissions and service
boundary levels are specified by regulatory
authorities as Service Rules
 Implementations of 802.xx in each band should adopt these
values to comply with the rules unless shown to be
inappropriate, where more stringent levels should be used
 Example, service providers are voluntarily using tighter
specifications than the rules require in the PCS band
 Receiver performance, including filters, are typically
not specified by the regulators
 Assumptions on these are, however, required to perform
coexistence analyses
 Interference temperature?
Submission
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Methodology
 Pick a few “primary candidate” bands
 Perform simulations using typical equipment
specifications
 Requires feedback from the WG on parameters such as TX
power, RX thresholds for various modulation schemes, ACS,
ACLR, etc.
 Needs network of cells, e.g. two tiers, with users distributed
throughout the cell coverage areas
Submission
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Methodology
 Given PHY parameters and appropriate path loss
models, links to every user is being set up
incorporating power control loops, burst profile
(mod/coding class) as dictated by SINR conditions,
etc.
 A snapshot of impact of interference on a victim
(Base or Sub) is then captured
 Impact on outage
 Impact on capacity (throughput)
 The process is then repeated many times to reveal the
statistics of interference
Submission
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Methodology
 Sample CDF plot
Outage threshold
Interference threshold
: Safe area (acceptable interference)
Submission
Joanne Wilson & Reza Arefi
May 2004
doc.: IEEE 802.19-04/0020r0
Methodology
 If following the Service Rules does not provide for
adequate protection, then recommend new
guidelines through:
 Determine “safe” geographical and/or spectral distance
between the two potentially interfering systems for
acceptable operation under the Service Rules
 Determine TX/RX parameters that enable “safe” operation
in geographical and/or spectral adjacency
Submission
Joanne Wilson & Reza Arefi