Subject: [NEXTEL-1] Re: Efficiency - Simulcast Synchronicity Style]

From: Marcel <[email-masked]>
Date: Wed, 09 Apr 2003 17:52:27 -0400

-------- Original Message --------
From: Jack Daniel <[email-masked]>
Subject: Re:  Efficiency - Simulcast Synchronicity Style

Dave,
True, and BER (or SQE) methods have proven merit in digital systems. 

However it requires the reception of a signal to establish BER and
identification of the current neighbor sites (by look-up tables from a
forward data channel at the current site or dynamic scanning in the
background). The viability of a neighbor list degrades rapidly in a LOS
situation for a moving vehicle. Before long, re-accessing the system can
take a lot of time, just like the first time the radio is turned on. 

In a data network, faster restoration means the number of retries for
incomplete packets can be reduced and that increases the data exchange
capacity without an increase in bandwidth. Extending this concept
farther, the system might become predictive of a LOS (based on direction
and speed) and store data until the mobile/portable confirms it is in a
good area, and spectrum efficiency/capacity would be very good.

In digitalized voice systems, if we could derive word or sentence breaks
(which is difficult), this same store-and-forward would assure
digitalized voice message delivery, but with some random latency between
words. I would assume occasional pauses would be preferable to loss of
total words or sentence segments. 

Basic location driven channel switching could work without a control
channel, on non-networks or trunked systems. The portable only needs 
itself and a preloaded boundary table. I concede this works better in a
public safety system where channel assignments are predictable over long
periods, as opposed to a cellular network where BTS channel allocations
may be dynamically adjusted to the current system loading at any time.

I'm thinking of new solutions that will either improve or replace
current methods of channel steering in multi-site public safety/private
radio system scenarios. 

But I may be wrong.........
Jack Daniel
================================================

Maples, Dave wrote:
> 
> Jack: I see your comments, but in most current systems I am familiar
> with the mobile receives from the current serving site the list of
> neighbors that it should be checking, and it checks those sites on a
> frequent basis to see if there is justification for a handoff.  It's
> generally done using BER.
> 
> For what it's worth...
> 
> Dave Maples

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---

From: Marcel <[email-masked]>
Date: Thu, 10 Apr 2003 09:29:26 -0400

Dave,

You are thinking about:

* Handover C/I+N Inbound  Hysteresis

* Handover C/I+N Inbound  Threshold

* Handover C/I+N Outbound  Hysteresis

* Handover C/I+N Outbound  Threshold

* Reselection C/I+N Outbound  Threshold

* Reselection Measurement period

You are correct iDEN is not the most advanced algorithm.

-------- Original Message --------
   From: "Maples, Dave" <[email-masked]>
Subject: RE:Efficiency - Simulcast Synchronicity Style

 Your comments are good ones.  The only thing I would point out is that a
properly-designed handoff system would alleviate the concerns you pointed out in
your first paragraph, because handoff decisions are actively coordinated
moment-by-moment between the subscriber unit and the site(s) involved, based on
a number of criteria besides just signal quality.  There are as I recall at
least three different criteria used in an iDEN handoff determination, and the
iDEN algorithm is not the most sophisticated one in use today. For what it's
worth...Dave Maples-----Original Message-----
From: ks4vt [mailto:[email-masked]]
Sent: Wednesday, April 09, 2003 5:47 AM
Subject: Re: Efficiency - Simulcast Synchronicity Style

     Well of course, but it also depends on the user base and the
     licensing considerations also. Most public safety voice systems
     cover too small an area for a cellular re-use concept and usually can
     put in a simulcast system with minimal issues. I would rather have
     all the frequencies operational at all the sites giving better joint
     probabality than to have the system think that I'm in a particular
     location just because I voted in a particular especially if they
     can't be utilized by anyone else because of the proximity of the
     other users.

     With a large system, like one that a state would put in, by all means
     this would kick butt and allow for frequency re-use cellular type
     system with steerable simulcast or single site transmitters.
     Motorola can do that with SmartZone and basis its decision on whether
     a user is affiliated with a particular zone and/or tower for groups
     and private calls. I'm biased though being I manage a 10 site, 28
     channel simulcast system over an approximate 2500 square mile county.

     I agree on the data...single site is the only way to go for best thru-

     put on a multichannel system and simulcast wouldn't be a good choice
     on this application.

     "Maples, Dave"
     <dave.maples@n...> wrote:
     > All: If I understand what was written it looks a lot like an idea
     that I have been kicking around for a while.  I have been thinking
     for about the last year that a "smart" simulcast system (one that
     puts channels in simulcast ONLY when they are REQUIRED to be in
     simulcast to serve the end users, and leaves them separate otherwise)
     would allow the operators to more efficiently use their assets for
     things like private calls and (in particular) mobile data.  The
     simulcast TIMING would be there and set up, but the information
     routed to each repeater might or might not be the same, depending on
     what the controller determined to use the channel in question for at
     the time.
     >
     > If a given agency's requirement were always and only group call,
     then this wouldn't provide any benefit.  However, one of the primary
     reasons that private calls and data calls are generally NOT supported
     on many simulcast systems is that it burns up channels that can be
     better used for group calls.  If the system were smart enough to set
     up and allocate group call channels only as needed, and allow sites
     to function independently otherwise, the system operator could allow
     the private and data calls on the system and allow the system to
     manage them better.
     >
     > The advantage to this is that the operator will  obtain some
     additional spectral efficiency out of a given set of allocations,
     particularly to add data (perhaps achieving much higher data rates
     for a given traffic load, because the system could concatenate
     channels from a given site for a data burst if designed to do so).
     The disadvantages are (a) the system will be more complex, (b) the
     choice of site locations will depend not only on coverage but also on
     expected traffic, (c) the design has to take into account cochannel
     interference within the system, something that does not have to be
     taken into account today.  There may be other advantages and
     disadvantages.
     >
     > In order for this to work most effectively, however, the subscriber
     units need to be able to hand off from one serving site to another
     automatically even while transmitting, so that an end-user doesn't
     fade to nothing during a call.  Current FDMA technologies don't
     really allow for this while transmitting, although TDMA and CDMA do.
     >
     > SmartZone is an effort in this direction, but since the end units
     are not full-duplex devices, handover doesn't work as well as it does
     in the full-duplex arena.
     >
     > Just my opinions, of course, and all comments are welcome.
     >
     > Dave Maples