Publishing Venue
Motorola
Related People
Authors:
Keith Eberlein
•
Elizabeth Esker
•
David Helm
•
Stephen VanSickle
Abstract
The following relates to the internal digital voice voting operation in a Comparator. If a Comparator has multiple Base Station ports hooked up to it, its voter needs to collect the corresponding individual frames coming from those ports and select the best components of those frames to for- ward on to the rest of the system. In order to collect the frames, when the first frame arrives at the voter, a window is opened. Any frame with a matching frame type from the other ports, that arrive while this window is open, will be included in the voting process.
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MOTOROLA Technical Development5
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VOTING WINDOW BASED ON DIFFERENTIAL DELAY AND FRAME JllTER
by Keith Eberlein, Elizabeth Esker, David Helm and Stephen VanSickle
BACKGROUND SOLUTION
The following relates to the internal digital voice voting operation in a Comparator. If a Comparator has multiple Base Station ports hooked up to it, its voter needs to collect the corresponding individual frames coming from those ports and select the best components of those frames to for- ward on to the rest of the system. In order to collect the frames, when the first frame arrives at the voter, a window is opened. Any frame with a matching frame type from the other ports, that arrive while this window is open, will be included in the voting process.
To determine the size of window to open, the Comparator's voter takes two things into account: 1) the amount of differential delay the port that receives the first frame of a given frame type has corresponding to the other ports and 2) the maxi- mum amount of jitter that can be introduced between frames coming from different ports. Thus, when a frame arrives from a port, the voter deter- mines that port's differential delay, adds on the max- imum jitter time and opens a window for that amount of time. This is done for the first frame of every frame type to arrive for the duration of the call.
Since the airtime difference between frames leaving a subscriber is known, that information can be used to determine when we expect frames to arrive at the voter and likewise when they should leave the voter. So, a solution to this jitter problem is to change the voting algorithm to calculate the voting window differently based on if a frame is the first frame to arrive for call or is a follow-on frame. If the frame is the first frame to arrive for the call, calculate the voting window the old way, by using the port's differential delay and adding the maxi- mum amount of frame jitter time. If the frame is a follow-on frame, calc...
