IEEE 802.16 Meeting

IEEE 802.16.2

RA effort was focussed on this Task Group writing a Recommended Practice Document for Broadband Fixed Wireless Access complementing the air interface standard being written in task group 802.16.1. The air interface will cover BFWA systems able to operate in frequency bands over the range 11 – 66GHz.

Status of the Recommended Practice Co-existence document

During an Interim meeting held in Ottawa (not attended by the RA) several issues had been discussed leading to conclusions that had not been communicated to the entire "co-existence group" until the opening session of this meeting. A number of the key issues were:

1. For adjacent area co-ordination, it was agreed that the trigger level for co-ordination based upon an acceptable level of interference (6dB below the receiver noise floor) into a victim BFWA system would apply at the boundary of the interfering operators licensed area.
2. The boundary trigger level quoted as a Power Flux Density = -114dBW/MHz/m² derived from the acceptable level of interference above, would be based upon an aggregate of all the interference from an interfering operators licensed area.
3. For adjacent frequency block interference, the same trigger level would be used for assessing interference radiated in adjacent frequencies.

As a result contributions were presented and reviewed that proposed text for the document based on these decisions.

Both one other regulator present and the RA expressed concerns with some of these issues and the burden they placed on operators for the following reasons:

1. The original PFD value quoted above was originally proposed by Industry Canada based on an assessment of interference from a single transmitter evaluated at the border of a neighbouring licensed area located some 60km away.

2. This limit was originally proposed as a single interferer limit not an aggregate interferer limit.

3. The decision was based on a simulation "informally" presented by the Chairman which was never posted on the group web site for scrutiny and is an extremely pessimistic worst case.

4. The aggregate interferer method requires an operator to "simulate" his entire expected deployment in advance of actual deployment in order to assess the interference at the boundary that a neighbouring victim operator is likely to suffer.

5. Although the PFD limit at the boundary provides complete protection to a neighbouring operators stations right up to the edge of his licensed area, this is at the expense of requiring the interfering operator to carry out "co-ordination calculations" for every station (base and terminal) in his deployment (in advance).

Other Contributions

TTP Communications presented an overview of their work developed to assist the debate within Europe on co-existence issues and the work of SE19 to develop the report on the co-existence of FWA deployments in the 26/28GHz bands. This included detail and comparison of the ISOP (Interference Scenario Occurrence Probability) and IA (Interfered Area) approaches addressing the adjacent frequency block issues. This was well received and some further discussion is needed to examine how this work can be addressed in the practice document.

Other inputs (from Nortel and PT (?))addressed specific sections and the philosophy behind the practice document including the issues mentioned above regarding PFD limits and their application. During these presentations the concerns highlighted above were expressed.

Further Work

In order to reinforce our opinions regarding the PFD limit and its application, the RA provided a brief resume of the approach being suggested for adjacent area co-ordination in the UK (and SE19). A commitment was made to the chairman to provide a detailed contribution on the issue to the next meeting. This contribution will provide detail of our simulation work (carried out by Aegis- BFWAtg(00)03) that underpins our approach to this issue.

Further work on the adjacent frequency block issue is also required. The methodologies suggested to date fall short of a complete set of recommendations. The issue of any required frequency offset (e.g usually a guard band) associated with this process is unclear.

Generally the document continues to fall short of any clear substantive recommendations for co-existence (e.g. guard bands, separation distances and so on) which will attempt to be addressed over the coming weeks.

Next Meeting

The next meeting is an interim 802.16.2 scheduled for xth – yth October following at least one tele-conference on issues raised at this meeting.

Other Issues

The intention is that once this Recommended Practice Document is stable (around November ), the group will go on to address the co-existence issues for BFWA in frequency bands below 11GHz. This will support the work of task group 802.16.3 who are writing an air interface standard for BFWA in these frequency bands.

Barry Lewis
RA2 / BFWA

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14th July 2000