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Li,
1. Probably 3
frames will be needed for most of implementations
2. For
systems targeting SDMA, the MAC frame will be longer than
3-4ms.
2. For VoIP,
not necessarely one needs retransmissions, the codecs are tolerant to
packet losses.
Regards,
Marianna
Jin,
I am a little puzzled
by your estimation. Note that when a physical frame is transmitted, it is also
received at the same time. Unless the receiver has to take the entire time
duration of a physical frame to finish the decoding after the frame has been
received, the ARQ loop delay seems to be dominated by the two TX physical
frames, not four.
In addition, the use
of small frame size is not uncommon in other technologies. For example, in
HDR, the slot time is 1.66ms. Voice traffic often has delay constraint of 20
or 40 ms. Considering the scheduling jitter and retransmission requirement, 10
ms ARQ loop delay does not seem to be terribly small.
Regards,
Junyi
-----Original
Message-----
From: Marianna
Goldhammer [mailto:marianna.goldhammer@alvarion.com]
Sent: Thursday, October
30, 2003 8:05
AM
To: Jin-Weon Chang;
stds-80220-requirements@ieee.org
Subject: RE: stds-80220-requirements:
4.1.9 Latency- ARQ loop delay
I agree
with your comments.
In my
understanding, video teleconf needs the lowest delay, I
guess
that 40-50ms
for ARQ loop delay should be enough.
-----Original
Message-----
From: Jin-Weon
Chang [mailto:jwchang1@samsung.com]
Sent: Thursday, October 30, 2003 4:16
AM
To:
stds-80220-requirements@ieee.org
Subject: stds-80220-requirements: 4.1.9
Latency- ARQ loop delay
In the section 4.1.8 Latency "ARQ loop delay" is
required to be less than 10ms.
If I understand the ARQ loop delay correctly, it
includes
- TX time of a physical
frame,
- Propagation time over the
air,
- RX time of a physical
frame,
- Processing time for
acknowledgement,
- TX time of a ACK/NACK frame,
- Propagation time over the air,
and
- RX time of an ACK/NACK
frame.
ARQ loop delay includes 4 times of physical
frame
if we assume ACK/NACK information is transffered in
a physical frame.
Limiting the delay within 10ms results in limiting
the size of a physical frame
This requirement will highly restrict physical design of
MBWA.
I think the size of a physical frame should be
determined
considering not only delay factor but also many
other factors.
Thus I would like to propose that 10ms requirement
in ARQ loop delay be removed.
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