1. Overlapping BSS Proposed Solution
June 2008
doc.: IEEE yy/xxxxr0
June 2008
Overlapping BSS Proposed Solution
Date:
Authors:
Graham Smith, DSP Group
Graham Smith, DSP Group

2. Abstract The problem of OBSS is quantified and examined
June 2008
doc.: IEEE yy/xxxxr0
June 2008
Abstract
The problem of OBSS is quantified and examined
A solution for OBSS is presented and discussed
A set of recommendations is given.
This revision is result of discussion following presentation at Jacksonville, May15th, 2008.
Graham Smith, DSP Group
Graham Smith, DSP Group

3. OBSS – Estimation of Size of Problem
June 2008
OBSS – Estimation of Size of Problem
Floor Plan of Apartments
Each Apartment
26 x 40 feet,
about 1000 square feet
Imagine similar floors above and below this one.
Indoor propagation loss formula used:
Lp = – log F + 40 log d + WAF (p) + FAF (q) F in MHz, d in feet
At shorter distances, the Free Space formula dominates,
Lp =– log F + 20 log d + WAF (p) + FAF (q)
The predicted propagation loss is the higher of the two.
Each wall (WAF) and floor (FAF) between apartments is assumed to be 10dB penetration loss (fireproof). Ceiling height is assumed to be 10 feet.
Graham Smith, DSP Group

4. Received Signal Strengths
June 2008
Received Signal Strengths 1
Inside same apartment 2
Next door (one each side) x2 3
Two away (one each side) x2 4
Three away (one each side) x2 5
Opposite 6
Opposite, across one (one each side) x2 7
Opposite, across two (one each side) x2 8
Opposite, across three (one each side) x2 9
Directly up and down x2 10
Up or down, neighbor (one each side) x4 11
Up or down, two away (one each side) x4 12
Up or down, three away (one each side) x4 13
Opposite, up and down x2 14
Opposite, up and down, two across x4 15
Opposite, up and down, one across x4 16
Opposite, up and down, three across x4 17
Two floors directly up and down x2
30dB power control
Graham Smith, DSP Group

5. Number of OBSS – DFS and TPC
June 2008
Number of OBSS – DFS and TPC
Table 1 – Theoretical OBSS for Apartments sq. ft.
Frequency Band
Number of Interfering Networks
Interfering Networks per 20MHz Channel
Interfering Networks per 40MHz Channel
2.4GHz 31 10
5GHz 27
0-1 3
Ideal DFS reduces problem significantly!
5GHz for Home!
Received signal strength within each apartment is high, better than -40dBm.
Theoretically, therefore, the power could be reduced by 30dB
with no deterioration in the throughput. Solves OBSS!
Table 2 – Theoretical OBSS with 30dB Power Reduction
Frequency Band
Number of Interfering Networks with 30dB power reduction
Interfering Networks per 20MHz Channel with 30dB power reduction
Interfering Networks per 40MHz Channel with 30dB power reduction
2.4GHz 8 3
5GHz 4
Graham Smith, DSP Group

6. Effects of OBSS - 1 June 2008 # Network A OBSS Network B Effect Result
Legacy
Traffic simply competes
Reduced bandwidth in each network
No lost packets
Not recommended for streaming 2
EDCA
Higher priority traffic in Network A will drive down traffic in Network B
AC_VO and AC_VI traffic dominates. Could be OK for streaming traffic but no admission policy
Network A “wins” 3
Traffic competes on a priority basis. Networks compete on an ‘equal’ basis
No real protection for streaming traffic in either network
Graham Smith, DSP Group

7. June 2008
Effects of OBSS - 2 #
Network A
OBSS
Network B
Effect
Result 4
Admission Control
Legacy
Higher priority traffic in Network A will drive down traffic in Network B
AC_VO and AC_VI traffic dominates. Could be OK for streaming traffic
Network B bandwidth can be drastically reduced 5
EDCA
Traffic competes on a priority basis.
Admission Control in Network cannot control traffic in Network B
No protection for admitted traffic in Network A 6
Admission
Control
Traffic competes on a priority basis.
Admission Control in either Network cannot control traffic in other Network
No protection for admitted traffic in either Network
These cases are cause for concern, Admission Control is intended
to provide QoS ‘protection’, and it breaks down in OBSS!
Graham Smith, DSP Group

8. Effects of OBSS - 3 June 2008 7 HCCA Legacy
Scheduled TXOPs in Network A also apply CFP to Network B.
Full protection for scheduled traffic in Network A
Network B bandwidth reduced 8
EDCA 9
Admission Control
Scheduled TXOPs in Network A also apply CFP to Network B
Admitted traffic Network B is lower priority than scheduled traffic in Network A
Both Networks using TSPECS 10
Each HCCA AP will admit streams and allocate time to them BUT each AP and STA will obey the TXOP allocation of the other.
No guarantee that each Network can allocate time when it needs to. ,
Reduced protection for scheduled traffic in either network.
Graham Smith, DSP Group

9. June 2008
OBSS and QoS
For non-QoS (non-real time streaming) applications OBSS is simply a sharing or reduced bandwidth per network – Not a significant problem
OBSS is a significant problem ONLY when QoS is used AND when some ‘guaranteed performance’ is at stake
Graham Smith, DSP Group

10. OBSS – Existing Problem for QoS
June 2008
OBSS – Existing Problem for QoS
Table clearly shows that OBSS is a problem for when it is intended to be used for applications that require QoS.
EDCA does not address the problem at all.
EDCA Admission Control only solves the bandwidth allocation problem within its own network and does not address OBSS.
HCCA does overcome OBSS problems in all but the case where two HCCA networks overlap.
Conclusions:
EDCA has an OBSS problem in all cases except when overlapping with non-QoS networks
HCCA does not have an OBSS problem except when overlapping with other HCCA networks
Graham Smith, DSP Group

11. Solving OBSS Ideal Objectives:
June 2008
Solving OBSS
Ideal Objectives:
HCCA and Admission Control QAPs can co-operate
Admission Control QAPs co-operate (Note: Still not protected against EDCA OBSS)
HCCA networks can co-operate
Channel Selection is first important step and practical
TPC not to be relied upon
TPC works in example of apartments, where the range is somewhat limited, but difficult when applied to other scenarios, e.g. Houses, where the ranges are more varied
Graham Smith, DSP Group

12. QAP = HCCA or EDCA Admission Control
June 2008
Basic Methodology
QAP = HCCA or EDCA Admission Control
QAP builds knowledge of expected QoS load, “QLoad”
QAP advertises “QLoad” element
Channel selection to try to avoid another QAP
If must share, selection based upon relative “QLoads”
QAPs negotiate bandwidth sharing
Sharing HCCA QAPs must coordinate TXOPs
Graham Smith, DSP Group

13. June 2008
OBSS – Basic Steps
Using the TSPECs, QAP ‘A’ builds knowledge of the QoS demands of its network, we shall call this the “Q Load”
When QSTAs associate, they send their TSPEC(s) corresponding to their expected requirements
AP sends requests for ‘candidate’ TSPECS,
AP builds up Q Load as ADDTSs arrive.
Another QAP ‘B’, looking for a spare channel or whether to share, would look at QAP ‘A’ to establish the Q Load ‘A’. Based on this QAP ‘B’ can make a decision on whether to stay or not
Assuming that QAP ‘B’ does stay, then it determines its own Q Load ‘B’
QAP ‘A’ and QAP ‘B’ negotiate the bandwidth, based upon their Q Loads
EDCA Admission Control only QAPs are now co-operating. HCCA and EDCA Admission Control are now co-operating
HCCA, QAP ‘A’ and QAP ‘B’ must harmonize such that they schedule TXOPs correctly with respect to both networks
Graham Smith, DSP Group

14. Steps 1-6 will now be examined in more detail.
June 2008
Steps 1-6 will now be examined in more detail.
Graham Smith, DSP Group

15. OBSS - TSPEC Exchange June 2008
Figure 10 – TSPEC Element
On association, a QSTA sends its TSPEC, QAP knows the STA’s requirement (s).
The TSPEC has Inactivity Interval set to 0 (may consider using ‘1’ as ‘0’ can mean ‘ignore’)
Causes the TSPEC to expire instantly, once accepted.
QAP recognizes this as a special case and know that the intention is for the QSTA to inform the QAP of its expected load
Note that the QAP must remember the allocation required
for all the ‘sign on’ TSPECs
Graham Smith, DSP Group

16. QAP ‘Q Load’ Reporting June 2008 Not adequate for purpose
QBSS Load element Format
Not adequate for purpose
Propose to add or replace similar new Element – “Q Load Element”
This is important
More later!!
Scheduled Slot field
Base timing for the Scheduled Service Intervals that the HC is using (see later)
QLoad Self
Potential QoS traffic for this QAP
QLoad Total
Potential QoS traffic for sharing QAPs. If Total>Self, indicates sharing
Note: Also could be used in Fast Handoff avoiding need to pre-register
Graham Smith, DSP Group

17. Channel Priority – Finding a Clear Channel
June 2008
Channel Priority – Finding a Clear Channel
When a QAP is searching for a channel, it should do so in the following order:
Set CHP (Channel Priority) to 0
Check no other AP present
Check no other QAP present
If another QAP present, then check QAP Q Load is small enough such that the two can share
If QAP finds no other QAP present, then set CHP = 1
CHP = 1 “Supervisor”. Only one Supervisor
Graham Smith, DSP Group

18. Basic options for sharing ‘rules’ are:
June 2008
QAPs Negotiate
Basic options for sharing ‘rules’ are:
First Come, First served (FCFS). TSPECs are accepted, HCCA and EDCA, in the order they appear. Both QAPs must know the prevailing total Q Load so as not to over-allocate.
Negotiated Bandwidth
First AP (CHP=1) keeps its bandwidth, second gets what’s left
Simple Proportion (SPNB) Based upon the potential Q-Load of each QAP, the bandwidth is proportioned up between them accordingly. This way, each QAP knows its modified maximum bandwidth allocation
On-Demand Negotiated Bandwidth (ODNB) Basically, when a QAP receives an ADDTS request, that, if accepted, would take the QAP over the SPNB allocation, it must get permission from the other QAP to accept it.
Method for exchange and agreement is proposed (see later)
Suggest that no rule(s) need be mandated, ‘hooks’ to be in place and allow WFA to set rules if so desired
Preferred Methods
(they are easy)
Graham Smith, DSP Group

19. Wireless DS QoS CF-Poll (Null Data) for AP to AP communication
June 2008
Propose use of
Wireless DS QoS CF-Poll (Null Data)
for AP to AP communication
Graham Smith, DSP Group

20. Wireless DS QoS CF-Poll (Null Data)
June 2008
Wireless DS QoS CF-Poll (Null Data)
AP to AP QoS CF-Poll Address Fields
Function To DS
From DS
Address 1 2 3 4
Wireless DS RA
= QAP B TA
= QAP A DA
=QAP B SA
=QAP A
AP to AP QoS CF-Poll Frame Type and Sub-type
Type value
b3 b2
Type Description
Subtype value b7 b6 b5 b4
Subtype Description 10
Data
1110
QoS CF-Poll (no data)
QoS Control Field
Applicable Data Frame
Bits 0-3
Bit 4
Bits 5-6
Bit 7
Bits 8-15
QoS CF Poll
TID
EOSP
= 1
ACK Policy
Agg (11n)
TXOP Limit
Use TID field as identifier
Graham Smith, DSP Group

21. Use of AP to AP QoS CF Poll for Sharing
June 2008
Use of AP to AP QoS CF Poll for Sharing
QAP B sees QAP A has available bandwidth.
QAP B builds its QLoad, as STAs associate on this channel.
QAP B decides if wants to apply to share – if so
QAP B sends QoS CF Poll to QAP A
TID Field = 1000 NAV = 0, TXOP = QLoad
QAP A ACKs, then:
Approved: QAP A responds: TID Field = 1000 NAV = 0, TXOP = QLoad
Denied: QAP A responds TID Field = 1001 NAV = 0, TXOP = 0
If approved, both QAPs adjust the QLoads (self and total)
Use this to formulate a “mandated” sharing rule
Graham Smith, DSP Group

22. What if QAP A or QAP B get a new QSTA?
June 2008
What if QAP A or QAP B get a new QSTA?
New QSTA on QAP A :
QAP A gets ADDTS request (zero Inactivity Time)
If available space, QAP A increases the QLoad values
QAP A sends QAP B a QoS CF Poll, with TID field set to 1100 (say) and TXOP limit contains addition.
QAP B ACKs
QAPs adjust the Q Load values (self and total)
New QSTA on QAP B :
QAP B gets ADDTS request (zero Inactivity Time)
QAP B sends QoS CF Poll to QAP A
TID field = 1010 (special case “Request additional QLoad”)
NAV = 0, TXOP = duration of new TXOP request
QAP A responds with QoS CF Poll to QAP B
Approved TID Field = 1010 NAV = 0, TXOP = duration of new TXOP request
Denied TID Field = 1011 NAV = 0, TXOP = 0
QLoad values updated QAP A adjusts the time of start of QAP B TXOP period.
Graham Smith, DSP Group

23. Harmonizing HCCA Fixed Time Slot Idea Approaches a TDMA method
June 2008
Harmonizing HCCA
Fixed Time Slot Idea
Approaches a TDMA method
Each AP (HC) knows how much of the Time Slot it can use.
Suggested ideas:
Listen to each others QoS Polls, knowing the QLoad, QAP can know when to start it own Polls
AP to AP Schedule control – This is the preferred approach
Graham Smith, DSP Group

24. Harmonizing HCCA QAPs - FTS
June 2008
Harmonizing HCCA QAPs - FTS
Explanation of Ideal Scheduling of TXOPs
Schedule for QSTAs
Desirable that the start times of the TXOPs are maintained at the same interval.
This enables the QSTA use efficient S-APSD,
Maintain the minimum service interval (SI) requirement as per the TSPEC
Graham Smith, DSP Group

25. Where did this come from???
June 2008
Fixed Slot time 10ms
Min and Max Service Intervals for Voice and Video
Category
Minimum Service Interval
Maximum Service Interval
Voice
G711, G729, AMR-NB, AMR-WB, iLBC, EVRC, VMR-WB
20ms
G711,G729,G723.1
30ms
G726-32
10ms
Video
SDTV, HDTV
0ms
16ms
Where did this come from???
10ms fixed Slot
Graham Smith, DSP Group

26. QoS Polling Example - Ideal
June 2008
QoS Polling Example - Ideal
QLOAD Sharing
Accepted TSPECS
Actual TXOPs
QoS Polls set up TXOP
If early end, QoS poll
terminate TXOP
Graham Smith, DSP Group

27. Timing Options Problem: How does QAP B know when to start its TXOPs?
June 2008
Timing Options
Problem: How does QAP B know when to start its TXOPs?
If situation static, then QAP B could listen to QAP A Polls and “learn” the timing
What happens when streams disappear or new streams arrive?
QAP A Acts as “Supervisor” (CHP=1)
QAP A controls the 10ms slot timing
QAP A sends message to QAP B indicating end of TXOPs for this Time Slot, and time to start of QAP B TXOP periods.
Uses Wireless DS (AP to AP), QoS CF-Poll (null data)
This option #2 is proposed
Graham Smith, DSP Group

28. June 2008
AP to AP Poll
Graham Smith, DSP Group

29. Wireless DS QoS CF-Poll (Null Data)
June 2008
Wireless DS QoS CF-Poll (Null Data)
AP to AP QoS CF-Poll Address Fields
Function To DS
From DS
Address 1 2 3 4
Wireless DS RA
= QAP B TA
= QAP A DA
=QAP B SA
=QAP A
AP to AP QoS CF-Poll Frame Type and Sub-type
Type value
b3 b2
Type Description
Subtype value b7 b6 b5 b4
Subtype Description 10
Data
1110
QoS CF-Poll (no data)
QoS Control Field
Applicable Data Frame
Bits 0-3
Bit 4
Bits 5-6
Bit 7
Bits 8-15
QoS CF Poll
TID
=1111
EOSP
= 1
ACK Policy
=10 (No ACK)
Agg (11n)
TXOP Limit
= T
Use TID field as identifier
T is time to start of “other” AP TXOPs period
Graham Smith, DSP Group

30. What if QAP B does not hear the Poll?
June 2008
What if QAP B does not hear the Poll?
Desirable to avoid ACKs to the QoS Polls
Conditions are static, hence if QAP B misses a particular poll, then can safely assume absolute start time is same as last. Using QAP A to indicate the start time is to overcome long term clock drifts.
Graham Smith, DSP Group

31. What if a Third QAP comes along?
June 2008
What if a Third QAP comes along?
Is this too restrictive?
How good do we believe
DFS will work?
Probably OK for 5GHz
Graham Smith, DSP Group

32. Could be extended for more QAPs but must all hear each other
June 2008
Third QAP
Sees one AP with CHP = 1 and one AP with CHP = 0
Looks at Total QLoad determines available space and decides if wants to consider to apply
QAP C builds its QLoad, as STAs associate on this channel.
QAP C decides if wants to apply to share – if so
QAP C sends QoS CF Poll to QAP A (as per Slide 22)
TID Field = 1000 NAV = 0, TXOP = QLoad
Approved: QAP A responds: TID Field = 1000 NAV = 0, TXOP = QLoad
Denied: QAP A responds: TID Field = 1001 NAV = 0, TXOP = 0
QAP A is now responsible for “Handoff” QoS Polls to both QAPs
Keeps B where it is and fits C in between.
Seems to work
Could be extended for more QAPs but must all hear each other
Is this restriction OK?
Graham Smith, DSP Group

33. OBSS Summary June 2008 Two (three) HCCA networks could share
Two EDCA Admission Control networks could share
An HCCA and one or more EDCA Admission Control Network(s) could share
Proposed additions to the Standard are :
“Q LOAD Element” for HCCA and EDCA Admission Control QAPs
Rules and procedures for sharing
Admission Control only
HCCA only
Mixed Admission Control and HCCA
Fixed 10ms Slot time for HCCA
Use of Wireless DS QoS CF Polls (null data) for inter-AP negotiation and HCCA TXOP scheduling
Possibly “OBSS” Beacon Request Report (hidden APs)
Graham Smith, DSP Group

34. June 2008
Hidden QAPs
If QAP stays after Beacon Report, set CHP to 0 and sends OBSS Beacon Request
QAP B now knows of QAP A and its Q Load
QAP ‘A’ and QAP ‘B’ calculate their maximum allocated bandwidth, based upon their Q Loads and the SPNB method.
QAP A and QAP B must now harmonize their Scheduled Allocations
Graham Smith, DSP Group

35. Possible Beacon Report Exchanges for Hidden QAP
June 2008
Possible Beacon Report Exchanges for Hidden QAP
OBSS Beacon Request
Provides other QAP the Q Load element
Informs CHP
Graham Smith, DSP Group

36. Harmonizing SI – Direct Method
June 2008
Harmonizing SI – Direct Method
Direct Method (as per non-hidden QAPs)
Could be possible using a common STA
BUT
The QSTA may be in power save mode
If the first TXOP has been granted then the QSTA is prevented from transmitting, so sending the timer onto the other QAP is not possible
The only legitimate transmission from a STA to an AP outside its network, is the Probe Request
It is not advisable, or even allowed to change a scheduled time by too much.
Graham Smith, DSP Group

37. Harmonizing SI – Indirect Method
June 2008
Harmonizing SI – Indirect Method
QAP A CHP = 0; QAP B CHP = 1
QAP A determines that a scheduled stream to a particular QSTA is blocked and suspects that it is due to scheduling from the QAP B. In this case, QAP A shifts its TSF timer, at DTIM, in the positive direction by 5% of the slot time, i.e. 500us.
Similarly, QAP B determines that a scheduled stream to a QSTA is blocked and suspects that it is due to scheduling from the QAP A. In this case, QAP B shifts its TSF timer, at DTIM, in the negative direction by 5% of the slot time, i.e. 500us.
Can’t think of anything better, do we even need to consider this?
Graham Smith, DSP Group

38. 802.11n - 40MHz OBSS 40MHz Channels MUST use the OBSS proposals to:
June 2008
802.11n - 40MHz OBSS
40MHz Channels
Easy/intuitive to see how two 40MHz overlapping networks will be less efficient than separate, independent 20MHz channels.
MUST use the OBSS proposals to:
Try to find clear channel
If not clear, look for 20MHz channel
MUST introduce procedures for preventing or controlling OBSS and usage of 40MHz channels
Need to see if the same procedures as previously described can be used
Graham Smith, DSP Group

39. Questions Do we need to consider beyond two or three APs sharing?
June 2008
Questions
Do we need to consider beyond two or three APs sharing?
Do we need to consider more on ‘hidden APs’?
Is it reasonable to ask QSTAs to ‘sign on’ with the sample TSPECS?
Do we need a request from the QAP for “sample TSPECS”?
The QAP could simply build up the QLOAD as time goes on
Procedure on Slide 22 for new STAs also applies for new TSPECS
Do we need to mandate sharing rules?
Which one should be used?
Leave it to WFA?
Use AP to AP QoS Polls to exchange, similar to slide 22, 23
Mixed OBSS?
If Admission Control QAP is Supervisor, then only one HCCA QAP may share?
Should a second HCCA be forced to become Admission Control?
Could consider HCCA taking over as Supervisor (probably contentious)
If HCCA is Master then more than one Admission Control could share?
Graham Smith, DSP Group

40. 08/0457 r2* was presented in Jacksonville, May, 2008.
June 2008
08/0457 r2* was presented in Jacksonville, May, 2008.
Discussion afterwards indicated:
Want to Brainstorm more, in particular:
Look further at initial settings,
Does it stay stable under different conditions, e.g. Power cuts and re-starts, new APs and STAs joining the network(s)
* In this presentation, Slides 1 – 39 are basically the same as r2, but with some re-ordering for clarity. Slides from here on, are new.
Graham Smith, DSP Group

41. Ideal Channel Selection
June 2008
Ideal Channel Selection
CHP = 0
This is, of course, out of scope, but could be used in informative text and used by WFA for certification
Graham Smith, DSP Group

42. June 2008
Can Two APs have CHP = 1?
Although unlikely, we shall assume that a QAP with CHP = 1, picks up Beacons from another QAP, on the same channel, with CHP = 1. How do the QAPs sort this out?
Alternatives/Options:
HCCA precedence over EDCA Admission Control
Higher TSF timer
When QAP establishes its BSS it sets TSF timer to zero
QAP with higher TSF value is the “Supervisor” (One could have faster clock, but seems fair)
Use WDS QoS Poll interchange to confirm?
Higher QLOAD
1 and 2 are proposed.
Graham Smith, DSP Group

43. This exchange could be used at other times to confirm OBSS sharing
June 2008
Two QAPs with CHP = 1
HCCA QAP checks if other is also HCCA
If other is not, then sends “Supervisor Claim” WDS QoS Poll
Other QAP should ACK and then send “CHP set to 0” WDS QoS Poll
QAPs compare received TSF Timer in received Beacon to own TSF timer
QAP that has higher TSF timer sends “Supervisor Claim” WDS QoS Poll
This exchange could be used at other times to confirm OBSS sharing
Graham Smith, DSP Group

44. Supervisor QAP goes away
June 2008
Supervisor QAP goes away
RULE
If QAP with CHP = 0, does not hear Beacons (suggest a number) from Supervisor, then following:
QAP with CHP = 0 sends WDS QoS Poll “Is Supervisor There?”
Retry limit of 3?
IF Supervisor is there, responds with “Supervisor Claim”
If no response
If no other QAP on this channel then
QAP sets CHP = 1
If another QAP (CHP = 0) on this channel
Carry out procedure for higher claim
Sends “Supervisor Claim”
Graham Smith, DSP Group

45. June 2008 WDS QoS CF Polls To Supervisor from QAP with CHP=0 ACTION
Bits 0-3
Bit 4
Bits 5-6
Bit 7
Bits 8-15
Request for new (total) QLoad
1000 1 00
QLoad requested in units of 32us
Request for addition to QLoad
1010
Additional QLoad in units of 32us
CHP is set to 0
0001
Is Supervisor There?
0100
From Supervisor QAP with CHP=1
ACTION
Bits 0-3
Bit 4
Bits 5-6
Bit 7
Bits 8-15
Indication from Supervisor to another QAP of Time to start TXOP (HCCA sharing)
1111 1 10
Time to start of TXOP in units of 32us
New QLoad Accepted
1000 00
QLoad requested in units of 32us
New QLoad Denied
1001
Additional QLoad Accepted
1010
Additional QLoad in units of 32us
Additional QLoad Denied
1011
Supervisor Claim, CHP = 1
0000
Note: Bits 8 – 15 allows 8.192ms max for QLoad. Could consider using b7 as well.
Graham Smith, DSP Group

46. Proposal June 2008 Add new QLOAD Element
Channel Priority CHP
Slot time concept for HCCA
Use of TSPEC with Inactivity Interval set to 0 or 1 to build “QLoad”
Use of RDS QoS CF Polls for sharing (See previous slide)
Rules and procedures for Channel Selection and setting of CHP
Rules and Procedures for Sharing
Graham Smith, DSP Group

47. Next Step? Straw Poll? Has general agreement?
June 2008
Next Step?
Straw Poll?
Has general agreement?
Needs more analysis? If so, what/where?
Start writing?
Graham Smith, DSP Group