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# Collision Avoidance in Utility Meter Endpoints

IP.com Disclosure Number: IPCOM000031701D
Publication Date: 2004-Oct-05
Document File: 3 page(s) / 28K

## Publishing Venue

The IP.com Prior Art Database

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Collision Avoidance in Utility Meter Endpoints

[0001]       Time dithering may also be used to avoid collisions between transmitting meters such as bubble-up meters.  A time dithering routine for transmitting meters may help to ensure that bubble-up devices have different bubble-up rates, particularly within an area of high device concentration, to thereby avoid interference between devices.  An example of a bubble-up routine is as follows.

1.                 A bubble-up time is set at an initial time t(0), which is at an approximate midpoint between respective lower and upper bounds t(lo) and t(hi).  An offset value t(offset), which is a predetermined time granularity, is established.

2.                 The least significant bit (LSB) of a serial number in the device is examined.  If it is zero, then a new time value is set: t(new)=t(0)–t(offset).  If it is 1, then t(new)=t(0)+t(offset).

3.                 The next bit of the serial number is now examined.  If zero, then t(new)=t(old–t(offset).  If it is 1, then t(new)=t(old)+t(offset).

4.                 Step 3 is repeated at every bubble-up period, using the next highest bit in the serial number.  Since serial numbers are typically of even length, for the bubble-up period immediately after the most significant bit (MSB) is used, the bubble-up time is incremented by t(0).  The shift period determination then shifts back to the LSB.

5.                 If the bound t(lo) is reached, and t(new) is to shift down, t(new) cycles back to t(hi).  If the bound t(hi) is reached, and t(new) is to shift up, t(new) cycles back to t(lo).

[0002]       The use of an odd number of steps guarantees that any given endpoint device will eventually and repetitively cycle through all possible bubble-up rates.  The use of serial numbers helps guarantee that no two endpoint devices will take the same path through the possible bubble-up time periods when all devices have unique serial numbers.

[0003]       Previous bubble-up devices could potentially interfere with each other, and remain in interference for an indeterminate period of time.  This routine fixes that concern.  This embodiment allows for a network of bubble-up devices to change their bubble-up rates independently, so that no two devices will "track," each other (i.e. will not continue to bubble-up at the same time for an indefinite period).

Under this bubble-up system, the probability of collisions, i.e., 2 endpoints sending data at the same time, is minimized.  Further, this system allows data from all the devices to be gathered in a minimum amount of time (assuming appropriate time val...