Enhanced one way radio seven bit data network

Details Enhanced one way radio seven bit data network Enhanced one way radio seven bit data network

1996-01-02

1998-06-23

Ton, Dang

Multiplex communications

Communication techniques for information carried in plural...

Assembly or disassembly of messages having address headers

370477, H04J 300

Patent

active

057712387

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention generally relates to the area of data transmission over a one way radio system. In particular the invention relates to data transmission protocols used with a paging system having a transmitter and a plurality of portable selective call receivers (paging receivers) having an intelligent message handling facility. The invention extends to seven bit networks, eight bit ASCII and binary data transmission capabilities and provides an "over-the-air" encoded security management and control system for remote units on either type of network.
2. Description of the Related Art
A signalling protocol developed by the British Post Office Code Advisory Group (POCSAG) is widely used in paging systems. This signalling protocol was adopted by the CCIR in recommendation 584-1. POCSAG is a paging protocol which enables the transmission of tone, numeric and alphanumeric messages. The POCSAG protocol provides for the transmission of 128 seven bit characters as specified in CCITT ASCII Alphabet No. 5.
The POCSAG protocol as well as other 7 bit paging transmission protocols such as Golay Sequential Code (GSC) and ERMES paging system as defined by the European Telecommunications Standards Institute (ETSI) suffer significant limitations in their implementation by paging networks and in their application by end users. The limitations are caused by the protocols being based on a 7 bit code-set whereas all computer systems including hand-held, notebook and desk based computers are based on architectures which support 8 bit character sets (256 characters). These 7 bit paging protocols are essentially incompatible with the complete requirements of computing technology based on the extended ASCII 256 character set.
Several functional limitations are imposed by paging networks in their actual implementation of the paging protocols. Two of these are significant technical limitations which prevent the user from sending all the 7 bit characters specified by the paging protocols respective standards. The first technical limitation is related to Data-entry systems which enable users of the paging networks to use in-house computers to enter messages directly into the paging networks via modems and the dial-up telephone network. Data-entry programs resident on the paging network computers arbitrarily prohibit the user from entering specific characters. Telecom New Zealand and VodaaPage (UK), as an example, prohibit any message that contains one or more characters with values in the range of 0-31 and 127 as specified by POCSAG protocols CCITT ASCII Alphabet No. 5, (approximately 25% of the available characters specified by the Protocol). This limitation can be addressed to some extent by the network agreeing to modify the programs that control the data entry system which users can access. ASCII characters 8, 10 and 13 are however examples of characters that can not be permitted as they are used to control the users editing of a message via the Data-entry programs.
It is, however, not possible to remove the Data-entry restrictions on all the other prohibited characters as further limitations are imposed by the encoding and transmission control equipment that has been developed and selected for utilisation by the Paging Networks. The equipment manufacturers have implemented hardware equipment which is remotely controlled by the transmission of specified control characters. If these control characters are transmitted within a message, which has been entered directly by a user, the paging network may cease all transmissions. In the case of Telecom New Zealand any message containing ASCII characters 17 or 19 (XON and XOFF), which are flow control characters will cause the Network to cease transmission or interrupt its service.
A further problem imposed on users by paging networks is the insertion of arbitrary trailing characters onto the end of the user's message packet. Telecom New Zealand insert two ASCII 32 (space) characters on the end of each message. If the paging receiver wa

REFERENCES:
patent: 5146457 (1992-09-01), Veldhuis et al.
patent: 5293379 (1994-03-01), Carr

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