Nextel????? Message Board

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Technology Stocks : Nextel?????

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To: joe smith who wrote (14)	8/26/1996 3:37:00 PM
From: john k. hixon	of 48

Joe, This gets complicated, because "bandwidth" is an open ended question. iDEN (integrated dispatch enhanced network) utilizes 25 KHz wide channels (each channel is a specific frequency). The basic mode of operation is TDMA (time division multiple access) The modulated signal (each connection) is a 16 QAM (Quadrature amplitude modulation) signal. So each call on a specific frequency gets assigned a space on a 25 Khz block. In turn the call gets set-up on a specific TDM (Time division multiplexed) "slot". These slots are what control channel control, voice and data traffic. I can't get too more detailed than that. What did change though, were a couple of things since Nextel originally launched. The voice reproduction (bandwidth) dedicated to each connection has been effectively doubled. This sacrificed capacity for call quality. The capacity gets addressed by adding more sites and/or radios. So the quality of the calls have improved significantly (In comparison to initial impressions about two years ago). Although with some financial restraint, Nextel has continued to build their system over the past 4 years. In comparison to what's currently out there I think the quality of voice is very good. I'm told it is much clearer than the preliminary versions of PCS CDMA technology. The problem is analog cellular has been around for so long. Their systems are built far more than any competing technologies can achieve any time soon. But they have their own limitaions too. Most of the service providers have major problems with interference and this results in your crosstalk and dropped calls. I know this might not be what your looking for but hopefully it helps. --John

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