[STDS-802-16] Bandwidth related questions

[Kalash <kalash.kuhasa@gmail.com>]

Hi,

I have a few questions on some items pertaining to bandwidth allocation:
1. Request / transmission policy bit prohibiting piggyback request -
if this bit is set for a connection, does this prohibit just the grant
management sub-header for the connection's MPDUs or also the bandwidth
request header for the connection in a unicast grant to SS?
Basically, there are three types of requests that a connection can make:
a. Bandwidth request in grant management sub-header of the connection's MPDU
b. Bandwidth request header concatenated with MPDUs of same or other
connections' MPDUs
c. Bandwidth request header in a contention request region

Question is if piggyback is prohibited by R/T policy, can the
connection use (b) for bandwidth requests?

My understanding is that only grant management sub-header requests are
gated by this bit.

2. Request / transmission policy bit prohibiting broadcast BW requests
- does this cover the request header transmissions in multicast
polling groups? What if the SS is part of a multicast polling group
but the R/T policy bit  prohibiting broadcast BW requests for a
connection is set ON - can the connection use multicast polling
regions to make a contention bandwidth request?

My understanding is that the bit should apply to both broadcast as
well as multicast request polling regions.

3. Midamble insertion interval calculation - should the burst preamble
be accounted for while making the decision of whether to include a
postamble symbol?

Requirement is that there should be a postamble symbol if the number
of symbols after the last midamble is greater than half the midamble
insertion interval. Consider the following case:
   Data grant - short preamble = 1 symbol
   Total grant (including preamble and midambles) = 21 symbols
   Midamble insertion interval = 8 symbols

If preamble is included in the calculation, then a postamble must be
added; if not the postamble is not required.

My understanding is that the preamble also counts towards the calculation.

4. Is it a requirement for the BS to allocate a single unicast grant
to the SS per UL-MAP? Can the SS assume that the BS will combine all
the allocations to the SS into a single UL-MAP IE? Does the
specification explicitly mandate this requirement for the BS? If it
does not, should this requirement be mandated?

My understanding is that it is not required for BS to allocate a
single unicast grant per UL-MAP to the SS (i.e., it can grant zero or
more per UL-MAP). How ever, it is inefficient to use more than a
single IE for per SS allocation.

5. What is the SDU size of the UGS allocations from BS point of view?
Is this just the minimum reserved traffic rate divided by the maximum
latency? I am at a loss in understanding why this information is left out of 
the specification - especially considering that a wrong value can cause 
the UGS connection not to pass any traffic.

My understanding is that UGS grant size = minimum rate / maximum latency

6. Can SDUs from UGS connections be fragmented - nothing in the
specification prohibits this but fragmentation is always an overhead.
In DOCSIS, UGS SDUs cannot be fragmented, but there are some very
good arguments why fragmentation should be allowed on UGS connections.

My understanding is that the UGS connection SDUs cannot be 
fragmented - SS does not have an easy way to provide a feedback to 
BS about pending UGS fragment SDUs.

7. Can UGS connection SDUs be packed together -again nothing in the
specification prohibits it? In DOCSIS, UGS SDUs cannot be packed
(concatenation is closest concept to packing in DOCSIS)

My understanding is that the UGS SDUs may be packed as long as they
are not fragmented.

8. How is the tolerated jitter enforced? Consider the following scenario:
Frame duration - 10 msec
UGS connection - each allocation is 8 symbols
Maximum latency 20 msec
Tolerated jitter - 2 msec
Frame 1 - allocation starts at symbols 4 and ends at symbols 11.
In the frame 3, when the next allocation is due, is an allocation any
where in the UL sub-frame considered okay or should the allocation be
between symbol 4 and (symbol 4 + 2 msec)?
Reason I bring this up is that DOCSIS requirement is very strict for
the UGS allocations - all the allocations are strictly tied to the
first allocation for the connection with the following restriction:
     Ti + maximum latency <= Ti+1 <= Ti + maximum latency + tolerated jitter
Is it the same here or different?

My understanding is that any allocation in the frame is the same as
if it were at the beginning of the frame.

9. How is the DL preamble configured - is it a per SS parameter? Is it
per DIUC parameter? Or it expected to be enabled for all transmissions
when certain conditions are met?

Appreciate any clarifications/comments/flames :)

Thanks
Kalash