1. TIM Broadcast Date: 2007-05-11 Menzo Wentink, et. al. Author(s): Name
Company
Address
Phone
Menzo Wentink
Conexant
Oudegracht 3, Utrecht, Netherlands
Jari Jokela
Nokia
Visiokatu 1, Tampere, Finland
Marc de Courville
Motorola
Parc les Algorithmes, Gif-sur-Yvette, France
Bob O´Hara
Cusco Systems
3625 Cisco Way, San Jose, CA
Allen Thomson
170 W Tasman, San Jose, CA
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Menzo Wentink, et. al.

2. Changes to Normative Text
The feature is now optional
therefore TIM Broadcast Information is now also present in Beacon and Probe Response frames
TIM frames are not transmitted when no client requested it
TIM Broadcast information also present in (Re)Association Request frames
TIM frames transmitted once per DTIM period instead of once per Beacon Period
A Beacon Check indication has been added to the TIM frame, to indicate that a client shall inspect the next Beacon
Limited requirement to one TIM frame instead of two
two TIM frames is advisory
Menzo Wentink, et. al.

3. Introduction
TIM Broadcast is a mechanism to receive the TIM field with as little overhead as possible
To this end, the AP transmits two TIM frames per beacon period
one TIM at the same rate as the Beacon
one TIM at a higher rate which is not DSSS (i.e. OFDM)
TIM Broadcast has advantage over receiving a Beacon or a Probe Request:
1,620 us Beacon (all Rx)
1,024 us Probe Request/Response (152us Tx)
36 us TIM frame at 24 Mbps (all Rx)
Menzo Wentink, et. al.

4. New Action Frame and IE TIM Action Frame TIM Broadcast IE Category
Check Beacon
TIM
Octets: 1
6-257
TIM Action Frame
Element ID
Length
TIM
Offset 1
Rate 1 …
Offset n
Rate n
Octets: 1 2
TIM Broadcast IE
Menzo Wentink, et. al.

5. Overhead
Assuming a beacon period of 100 ms, the overhead of two TIM Broadcasts per beacon period is 0.6% (588 us out of 100 ms)
Menzo Wentink, et. al.