Motorola has developed the FLEX TM family of high-speed transport protocols which is being positioned as a standard for the wireless communications industry. While Motorola owns and controls this family of protocols, Motorola is licensing the protocols to enable their acceptance globally. The first family member is the FLEX TM high speed one-way paging protocol. It is capable of operating at data speeds of 1600, 3200 or 6400 bits per second. The format supports the delivery of tone only, numeric, alphanumeric and binary data to remote receivers. It sends paging data in fixed size batches  which  utilize a data interleaving  scheme similar  to that of  the Motorola  Golay  format (described briefly as part of the

ERMES discussion).

This interleaving provides for a high degree of burst error protection. Error protection is further enhanced by imbedded checksum information within the transmitted data. A number of consecutive interleaved blocks are grouped together into frames. Sequences of frames are repeated cyclically each hour.

The protocol is time synchronized, transmitting frames at very specific time intervals. The first frame typically starts on the hour. Pagers may be set up to normally expect its pages to arrive during certain transmission frames, yet, under system control operate to receive pages in frames which occur more often. This may be used when a channel is lightly loaded in order to send several pages at one time rather than spreading them over a longer period of time. It also allows FLEX TM to be introduced into an existing paging channel minimizing the amount of airtime used by FLEX TM until traffic volumes dictate additional airtime. When pagers are operating to only expect transmissions to occur in their normal frames, battery life may be extended at the expense of a slightly longer message latency.

At its highest operating speed, the protocol simultaneously delivers 4 time multiplexed data streams at a time, allowing each pager to continue operation at a low speed (1600 BPS) while the channel carries 6400 BPS. The paging format is capable of addressing more than 1 billion device addresses. Frames are created in such a way as to minimize the time it takes a pager to determine if the frame contains a message for its address. This further improves the battery life of FLEX TM based pagers.

FLEX ^TM provides a range of operating modes which allow the paging terminal a great degree of flexibility in optimally transmitting pages on queue based upon traffic loading conditions. Long messages may be segmented into shorter pieces and reassembled by the receiver. This allows shorter messages to be transmitted between the segments of larger messages. Other features allow certain page requests to be replaced by shorter transmission sequences thereby allowing more pages to be delivered in a given period of time.