1. doc.: IEEE 802.15-<doc#>
<11 January, 2008r>
doc.: IEEE <doc#>
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Discussion on Non-Beacon Operation Mode]
Date Submitted: [24 June, 2008]
Source: [Ning Gu, H.Q.Huang, Jie Shen, Qin Wang, Liang Li, Xiao Tao, Haitu Liu] Company [Vinno, SIMI and USTB]
Address [Beijing, China]
Voice:[ ], FAX: [ ],
Re: [IEEE e group]
Abstract: []
Purpose: [To promote discussion in IEEE e Study Group]
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P
<author>, <company>

2. Motivation
After several-round discussion and meetings, re-consider the basic problems in Non-Beacon scheme
List out some comments to TSCH scheme
List out some modification solution to IEEE for Non-Beacon Networking

3. Present Problems in Non-Beacon Networks
Possible Performance consideration:
Coordinators must be always on.
Devices might overhear a lot of packets.
high power consumption for idle listening.
Accuracy and lower efficiency
Less Synchronization accuracy in networks, which will affect the bandwidth efficiency.
Hard to discover neighbors without beacon (or without time synchronization)
Indirect data transfer isn’t supported without beacon, need multi-hop QoS support.
More Confliction in networks.
Finally, the necessary Timing info of Networks is sourced from upper layer

4. Discussion on TSCH Centralized network & Time synchronization
TSCH is a centralized Network, and Sink maintains global network information.
The network needs global time synchronization. It may need one high-quality clock in each node.
Time delay may be longer for requesting a new time slot as the request is relayed on Sink.
Centralized channel assignment algorithm
The Channel assignment algorithm may be complex, which may limit the network performance.
Efficiency
Fixed assigned slots are inefficient for dynamic traffic flow.
Nodes have to advertise (broadcast) itself in every slot frame, thus energy inefficient.
A node need to listen every neighbor in each time slot, which waste energy if there’s no data transfer.

5. Comparison of EGTS and TSCH
<11 January, 2008r>
doc.: IEEE <doc#>
Comparison of EGTS and TSCH
EGTS
TSCH
Where is the start point of time-slots
Beacon slot
Advertisement define
How to announce timeslots allocation
With beacon packet in MAC layer
With advertisement packet in upper layer
How does each node synchronizes with others
With beacon
With sync packet in upper layer and ACK in MAC layer
Functionally, advertisement is same as beacon, but not in MAC layer. In another word, if moving advertisement to MAC
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6. Other Possible Improvements for NB-Mode
Add the Sleep Scheduling
Suggest one Asynchronous sleep scheduling mechanism.
Efficient wakeup method is needed.
Build up one Public Channel
Build up Separated control-channel and data-channel.
Control channel is public, use CSMA to transfer control packets.
Add a new packet (chirp frame) as wakeup signal.
Data channel is assigned by distributed three-way-handshake mechanism.