Appendix C

MOTOROLA'S NEW FLEX(tm) HIGH SPEED PAGING CODE

Present paging systems have the receivers operating at 300/600 bits per second (Golay Format) and 512/1200 bits per second (POCSAG). Higher speeds are being targeted to improve throughputs in a system. POCSAG at 2400 bits per second has been successfully implemented and the new FLEX high speed paging code developed by Motorola will give much more advanced features in helping the paging industry break through today's capacity limitations for new growth and expansion. FLEX paging code is a fully synchronous paging code. By keeping the receiver's electronics continuously in synchronism with paging transmission, FLEX code opens the door to an entirely new generation of paging technology worldwide. Some of the features and benefits of FLEX are as follows:



Optimized Efficiency and Throughput

More than 600,000 numeric pagers per channel at maximum speed, over four times over POCSAG 1200. With alphanumeric pagers, FLEX can accommodate almost five times the throughput supported by POCSAG 1200.



Minimum Investment in Upgrading Infrastructure

FLEX can be used both on dedicated channels or mixed on an existing system with POCSAG or GSC without compromising performance. System operators need not move to the ultimate FLEX speed of 6400 bps in one single step. They can add FLEX 1600 to their existing 1200 bps system by upgrading existing terminals, and continue servicing existing pagers in the field with relatively little investment in infrastructure components. As future demand picks up, they can elect to move to 3200 bps and then 6400 bps as they populate the market with upwardly compatible receivers. The upward migration is completely transparent with no degradation of service to existing users. Pagers currently in service will continue to operate normally, while of course new FLEX pagers, which can automatically adjust themselves to transmission speed, will enjoy all the features and benefits designed into them.



Maximum Battery Life

Since FLEX is a fully synchronous paging code, it allows a pager to engage itself only when a message is expected to be available in real time, and thereby substantially extending battery life. To paging subscribers, maximum battery life means lower operating costs, fewer battery changes, and availability of smaller pagers using smaller batteries.



Higher Integrity and User Confidence

FLEX offers maximum prudent error protection against possible errors caused by a multipath and faded environment. It is also designed to provide positive end-of-message control and optional missed-message flag indication to prompt the user to request for re-transmission. Even when the pager is out-of-range or turned off, FLEX will let its user know that a message has been missed. FLEX can handle pure tone alert, ASCII, HEX, numeric, alphanumeric as well as unformatted binary data streams.



Major Features of FLEXTM



The ERMES Coding Format

The European Community, as part of its 1992 initiative, had identified the need for a next generation paging service that would offer coverage throughout all of Europe. The goals of the European Radio Message System (ERMES) were concisely stated:

  • A high speed coding format operating at 6250 bps that offers roaming capability.
  • Dedicated frequency spectrum in the 169 MHz band supporting 16 adjacent channels.
  • The ERMES protocol is to be structured to maximize its performance and throughput on alphanumeric messaging.

    Four Level FSK Signalling is used for the ERMES system which requires unique infrastructure for system start-up allowing no easy migration path from present POCSAG operations.

    Similar to the POCSAG coding format, each ERMES pager is assigned to a specific time slot. When a pager senses it is not in its Home system, it begins its roaming routine. The ERMES system's 16-channel- batch assignments are positioned timewise so that when a pager finishes searching its batch on one channel, its assigned batch will be the first batch opportunity on the next channel. In this way there is no extended latency period for the roaming subscriber to receive their pages.

    The ERMES protocol also has the ability to offer a superior battery-saving performance when compared to the POCSAG protocol. A battery-save ratio approaching 200:1 in its Home coverage area is easily obtained with the ERMES protocol. This is about 35 times better than the 5.7:1 battery-save ratio available in POCSAG.

    When compared to POCSAG 1200 signalling, the ERMES protocol offers better than four times the throughput in subscriber capacity for 40 character messaging. When compared to numeric 10 digit messaging, the ERMES protocol provides only 2.5 times the throughput in subscriber capacity.



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    Copyright 1995, 1996, Motorola, Inc. All Rights Reserved.
    Last updated: June 5, 1996