Optional vs. Mandatory Paging Scheme
Original Post: Optional Paging Scheme Vs. Mandatory (SIG Forum)
Date: 2000-04-14
From a time analytical point of view , the optional paging
scheme doesn't initially seem to be any more efficient than the mandatory. It
does reduces the slave scan window ( from 10ms to 5.9375ms), but takes (50ms x
26) = 1.3s to go through all the necessary frequencies (in one train), which is
slightly slower than the time required for the mandatory paging scheme (1.28s).
Note: The main difference between the first
optional paging scheme and the mandatory scheme is the construction of the page
train sent by the pager. In addition to transmission in the even master slots,
the master is transmitting in the odd master slots as well.
Two possible advantages seem to exist for the Optional Paging scheme
- The reduced scan window might lead to reduction of the power consumption for
the slave. That may be important for applications (piconets), in which the
slaves need not page (operate always as slaves) and power consumption for them
is critic.
- The increased number of repetitions of each frequency before swapping over
to the other 'super'train. the Optional paging scheme repeats each freq. 26 x 8
= 208 times during 1,3s (each subtrain includes 8 freq. and is repeated 26
times). That is significantly more than it in the mandatory scheme where each
freq. is repeated only 128 times. This could be useful if the phase between the
master and slave was slightly off. A new train every 10ms (mandatory
scheme)might be a couple of ms off the slave clock, but a subtrain every 6.25ms
mightn't be.
However it is debatable if this advantages are worth modifying the whole
nature of a Bluetooth device i.e. a temporary changing of the system of slave +
master dedicated transmit/receive slots.
|
