Vista - ID scanner

I have a wireless scanner that constantly scan for IDs like the
following:


EF-1B
AG-D5
EF-1B
AG-D5
EF-1B
EF-1B
EF-1B
AG-D5
.... etc

each IDs represent a wireless device.

above IDs will updated from 1 sec to 8 sec or may be longer, depends
on how close the wireless device come close to the scanner.

any library / header I should use to implement a detection of wireless
device is go away (may be ID = EF-1B did not show up for more than 15
sec) then I assume EF-1B goes out of range / goes away

But I do want fast detection of which ID comes up front to the
scanner. which ID walks away from scanner.

Which C++ library / headers will help doing this? and any code
exmaple?



Extra Notes:
=================================
above show 2 wireless device in range with IDs EF-!B and AG-D5.

due to the wireless scanner's range is fairly short and not detect
wireless device IDs very quickly if not close enough.

sometimes IDs will show up in the buffer every 5 sec or 8 sec.

ideally, the scanner will detect IDs every 1 sec and print it out like
above if wirelsss device is close enough to wireless scanner.