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Dear
All, Following
an extensive study and analysis of the advantages and disadvantages of the
various HARQ timing and protocol schemes for the downlink and uplink and
further considering the overall performance and complexity of the 802.16m
system, we would like to propose a new option for the HARQ timing and protocol as
the way forward. Option 4: Asynchronous for downlink,
Synchronous for uplink The
new option is justified when the pros and cons of each scheme is separately
investigated for the downlink and uplink. In the downlink, since the
transmitter and scheduler are co-located at the BS, the benefit from flexible scheduling
of retransmissions can be maximized. Therefore, the asynchronous HARQ is more
advantageous in the downlink. However, the scheduler (BS) is apart from the
transmitter (MS) in the uplink direction, consequently, the scheduling gain and
flexibility from the asynchronous HARQ is less pronounced. In that case, the
effect of signaling overhead would be more dominant on the system throughput.
For this reason, the synchronous HARQ can be a better choice for the uplink. In
light of the above observation, we believe that the new option is the most
reasonable and well justified approach for 802.16m, and we would like to ask
the membership to carefully consider and support this option. Thanks
and Regards Sassan
Ahmadi and Jaeweon Cho Intel
Corporation and Samsung Electronics |