 We’ve all been to Roman Way for an upgrade, but what was it? Tom Carter explains… For the past few months, we have been upgrading your mobile terminals primarily to correct meter-reading problems since Dial-a-Cab is now required by some clients to show the meter fare at arrival time. At the same time, we have also been installing new software that attempts to correct some problems with the modem software. These problems, which impact the ability of the radio system to handle the data traffic efficiently, became apparent after all the old 7100 terminals were replaced. The first problem is the inability of the modem software to detect and handle the ‘Channel Busy’ |
MOBILE TERMINAL UPGRADES |
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condition. A radio channel enters this state when a ‘high water mark’ is reached and it simply means there are too many terminals on the channel. When this state is reached, the radio system informs the mobiles and they are supposed to migrate to a different channel. This was not working and the system allowed too many mobiles to attach themselves to a channel, causing that channel to slow down and its performance to degrade. The new mobile software now handles this condition. However, it is not the final solution since this condition needs to be controlled by the modem software itself. The second problem is the inability of the modem software to properly handle ‘Channel Scanning’. As most of you know, DaC has seven data channels and one voice channel. As mobiles moves around the city, they move from one channel to the next looking for the best signal. The way a mobile finds a new channel is controlled by an embedded list of channels that is called the ‘Channel Scan List’. When the |
mobiles were initially installed, they all had the same
channel scan list and because ‘Channel Scanning’ was not working, only the first few of the seven channels were consistently considered as a new channel. This caused the majority of the mobiles to lock onto one of the first 3 or 4 channels in the list and caused the ‘Channel Busy’ condition. During the current mobile upgrades, we have been redefining the ‘Channel Scanning List’ based on the normal starting position of the mobile. While these upgrades have been occurring, the modem supplier has been correcting their modem software. They have fixed the two problems described above and have also uncovered several other problems that would have a negative effect on the radio system. This new modem software is now being installed on all taxis that go to Roman Way. Once all taxis have been upgraded to this new version, any signal problems should all but disappear.
Tom Carter |
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