WO1999027696A1

WO1999027696A1 - Protocol for voice paging system

Info

Publication number: WO1999027696A1
Application number: PCT/US1998/025178
Authority: WO
Inventors: Howard H. Stover; Lawrence J. Karr
Original assignee: Clariti Telecommunications International, Ltd.
Priority date: 1997-11-25
Filing date: 1998-11-24
Publication date: 1999-06-03
Also published as: AU1798899A; ZA9810567B; CR5915A

Abstract

A protocol (10) for a digital stored voice paging system. The protocol (10) contains a multiplicity of limited frames each containing a short message section (12) and a voice data section (14). The short message section (12) contains repeated alert packets (16) for providing time diversity, and the voice data section is comprised of packets containing voice data streams. The packets of the voice data streams (20) are interspersed with one another and transmitted in scatter form throughout the length of the message time period, to improve the power consumption and reduce errors in voice message transmissions during digital stored voice paging operations.

Description

PROTOCOL FOR VOICE PAGING SYSTEM BACKGROUND OF THE INVENTION

1. Field of The Invention

The present invention generally relates to the field of modern telecommunication technologies and devices. More particularly, the present invention relates to the field of digital stored voice paging protocols of digital message paging systems.

2. Description of The Prior Art

The following is a brief summary of prior art references that are believed to be pertinent to the field of digital stored voice paging protocol and other operational features of the paging system.

United States Patent No. 3,846,783 issued to Apsell et al. on November 5, 1974 describes a system wherein all data is sent as audio tones over the carrier.

United States Patent No. 4,209,836 issued to Wiggins et al. on June 24, 1980 relates to linear predictive coding (LPC) speech technologies.

United States Patent No. 4,424,514 issued to Fennell et al on January 3, 1984 describes a receiver which responds to a message addressed to it, but delays the user alerting function of the receiver until some time following the reception.

United States Patent No. 4,477,807 issued to Nakajima et al. on October 16, 1984 describes a pager that can sort out repeated messages by brute-force data matching. The messages are not tagged or divided into segments. The contents of the stored message buffer are compared with those of the incoming message. United States Patent No. 4,479,124 issued to Rodriguez et al. on October 23, 1984 describes a system in which canned speech segments are combined and re-played as messages according to codes sent in a digital message, wherein no speech segments are actually sent over the air.

United States Patent No. 4,701,943 issued to Davis et al. on October 20, 1987 describes a refinement to digital stored voice paging wherein the digitized LPC speech is sent over the air at variable rates depending upon the system loading so that better quality and reliability are available at off-peak times.

United States Patent No. 4,713,808 issued to Gaskill et al. on December 15, 1987 describes a watch radio utilizing a time-slot system wherein a receiver is assigned to a slot with a unique number corresponding to its address. The packets are structurally similar despite the nature of the data, and each packet contains an address.

United States Patent No. 4,769,642 issued to Davis et al. on September 6, 1988 describes a paging system utilizing a digital pager having a radio receiver, an address decoder and memory controller (micro-computer) and a linear predictive coding (LPC) voice synthesizer, where the pager carries out simultaneous operations of paging signal reception and voice message reconstruction, and where the receiver has a dual port memoiy or similar device which permits compressed voice data to be stored and played back simultaneously.

United States Patent No. 4,885,577 issued to Nelson on December 5, 1989 also describes an analog voice scheme wherein there is no voice storage of any sort, and the paging terminal determines a delay for the radio so that it can set up to receive the voice message in real time.

United States Patent No. 4,897,835 issued to Gaskill et al. on January 30, 1990 describes a protocol used in a watch radio to allow for chaining longer messages into a series of packets that the receiver interprets as pointers to data packets or as data packets, wherein any packet may be of any type, and the packets themselves rather than their position indicate the nature of the contents and each contains an address. The protocol provides the ability to encode station identification information telling the receivers where to tune for alternate transmissions and what the message transmission time offsets are for each such station.

United States Patent No. 5, 155,479 issued to Ragan on October 13, 1990 describes a system that can be used in message watches, where the clock of the receiver adapts to the transmitter based upon measuring the interval between message frame events. A separate time keeping clock system is used which is updated based upon packet transmission starting time and is independent of the baud tracking clock.

United States Patent No. 4,965,569 issued to Bennett et al. on October 23, 1990 describes a paging system wherein all voice message are sent in analog form.

United States Patent No. 5,159,713 issued to Gaskill et al. on October 27, 1992 describes a system with precise message targeting and utilizing the system more efficiently by reducing repetition to a smaller subset of transmitters within the multi-transmitter network.

United States Patent No. 5,285,496 issued to Frank et al. on February 8, 1994 describes a secure paging system wherein the data are specifically encrypted prior to modulation.

United States Patent No. 5,309,154 issued to Mun et al. on May 3, 1994 describes a quasi-synchronous power-down cycle within the protocol which requires specific synch codes and framing but uses alternate codes within the structure to create instructions used for controlling the power. The receivers can go to sleep, but not completely, during which time they listen for a specific, long preamble code. They then come fully awake. The alternate preamble codes are used only by the receivers having the full power-down feature.

United States Patent No. 5,311,516 issued to Kuznicki et al. on May 10, 1994 relates to a method for reconstructing fragmented messages based upon codes which describe the number of fragments and which fragment a packet contains. United States Patent No. 5,412,719 issued to Hamamoto et al. on May 2, 1995 describes a digital stored-voice paging device wherein the voice information is transmitted as analog and then digitized in the pager.

United States Patent No. 5,481,254 issued to Gaskill et al. on January 2, 1996 describes a system that permits group messaging by creating codes which tell individual receivers to pick up the same message at a particular time slot.

United States Patent No. 5,455,579 issued to Bennett et al on October 3, 1995 describes a paging system wherein the voice information is sent over the radio channel and digitized in the pager where it is stored and then played back after decompression.

United States Patent No. 5,551,078 issued to Connell et al. on August 27, 1996 describes a synchronous protocol wherein the receiver power-off time is determined by the count of a repeated code sent in the data frame. The protocol includes the steps of determining an indication of one or both of the signal phase and frequency when the receiver is turned off, and then using this information as the counter time base.

United States Patents No. 5,556,081 issued to Yoshizawa on October 15, 1996 describes a battery saving scheme which has a variable receiver off-time determined by the repetition rate of a particular data pattern sent by the transmitter.

United States Patent No. 5,577,045 issued to Faris et al. on November 19, 1996 describes a scheme for displaying fragmented text messages with multiple display fonts. The fonts are used to indicate several things within various schemes. Messages with questionable data may, for example, have the uncertain segments shown in a different font. This is related to the operation of a system which has a message repeat scheme wherein the quality of messages may be improved over time by repetition and replacement of poorly received segments.

In simplex digital voice paging and messaging systems it is desirable to reduce the amount time used to alert a receiver that a message is scheduled for transmission. Since the total number of receivers is usually large compared to the number which actually have messages waiting at any given time, reducing the time needed for alerting receivers permits greater message "payload" as well as greatly improve the battery life of the receivers.

As demonstrated by the prior art references discussed above, a number of prior art protocols have been devised for standard paging and messaging applications which involve the receivers turning on periodically, and synchronously with the transmitter issuing a message, then turning off until the next message period. Digital voice paging, however, presents several new challenges not faced in numeric and tokenized brief message paging systems. Particularly, the relatively longer time needed to transmit each message demands that even greater attention be paid to reducing the non-message overhead and that the message time period be as open and flexible as possible to accommodate highly variable message lengths.

Therefore, it is highly desirable to design and develop a new protocol for digital stored voice paging systems that reduces the non-message overhead and allows the message time period to be open and flexible to accommodate highly variable message lengths.

SUMMARY OF THE INVENTION

The present invention is a unique protocol for digitally stored voice message paging systems. In another aspect the present invention provides a method of utilizing a unique protocol to reduce the amount of time used to alert a receiver.

The present invention provides a protocol for digital stored voice paging systems. In one of the preferred embodiments of the present invention, the digital voice message paging protocol comprises a multiplicity of limited frames, each containing a short message section and a voice data section. The short message section contains a plurality of packets, including packets repeating an earlier alert section, packets repeating a pointer section for earlier alerts, packets for a subsequent alert section, packets for a subsequent pointer section corresponding to the subsequent alert section, and packets for again repeating the pointer section for the earlier alert section, wherein the repeating of the pointers for the earlier alerts provides time diversity to reduce errors in message transmissions. The voice data section also contains a plurality of packets, comprising one or more voice data streams, wherein the voice data are randomly interleaved. The packets of each such stream are then interspersed with those of the other streams and transmitted in scatter form throughout the length of the message time period. In the preferred embodiment, the packets as described above are interspersed with one another such that the times between transmission of packets from the same stream are irregular and non-uniform in order to prevent synchronization with periodic channel fading phenomena. The operation of the protocol improves the power consumption and voice message transmission quality of the digital stored voice paging system.

The present invention digital voice message paging protocol has many unique features and advantages. Compared to the prior art voice paging protocols, the present invention protocol uses the receiver baud clock which is locked to the transmitter signal frequency and phase to establish the basic clock for all signal-related timing. In the present invention protocol, the times are fixed in the protocol and only vary to the extent that the voice data may be contained in one of several fixed data streams. Furthermore, in the present invention protocol, there are several regimes within each frame, each containing fundamentally different data with different encoding. The data is divided into packets of uniform length, but said packet are only for the convenience of locking the receiver in a multi-path environment, the packet divisions do not necessarily relate to the data domain. Some packets are tagged, but the tags only permit the receiver to achieve frame synchronization. The tags do not correspond to a receiver address. A packet of voice data would normally be intended for a single receiver, but a packet of alerts or pointers could be read by many units. No message pointer packet is specifically addressed to a particular unit, and the alerted units read and interpret a list of messages to determine the location of their data. The present invention protocol has the capability to use more than one station, without relying on a multi-station protocol for basic message redundancy. A special portion of the data frame may be devoted to this type of information which is not tagged and sent along with the normal data packets addressed to a particular receiver. In the present invention protocol, a receiver may read these data in any frame should it need to seek, for example, station availability data or an alternate station. The group messaging based on the present invention protocol is accomplished by setting multiple alert bits and then using an alternate multiply assigned address within the receiver unit which then knows to decode the message from the specified location in the normal manner.

Further novel features and other objects of the present invention will become apparent from the following detailed description, discussion and the appended claims, taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring particularly to the drawings for the purpose of illustration only and not limitation, there is illustrated:

FIG. 1 is an illustrative drawing showing one of the preferred embodiments of the present invention protocol for digital stored voice message paging systems, and particularly, the alert packet of the short message section of a frame of the present invention protocol. FIG. 2 is an illustrative drawing showing one of the preferred embodiments of the present invention protocol for digital stored voice message paging systems, and particularly, the pointer packet of the short message section of a frame of the present invention protocol.

FIG. 3 is an illustrative drawing showing one of the preferred embodiments of the present invention protocol for digital stored voice message paging systems, and particularly, the housekeeping or customized packets of the short message section of a frame of the present invention protocol.

FIG. 4 is an illustrative drawing showing one of the preferred embodiments of the present invention protocol for digital stored voice message paging systems, and particularly, the voice data stream header of the voice data section of a frame of the present invention protocol.

FIG. 5 is an illustrative drawing showing one of the preferred embodiments of the present invention protocol for digital stored voice message paging systems, and particularly, showing the unique mapping of the voice data streams in the voice data section of a frame of the present invention protocol.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Although specific embodiments of the present invention will now be described with reference to the drawings, it should be understood that such embodiments are by way of example only and merely illustrative of but a small number of the many possible specific embodiments which can represent applications of the principles of the present invention. Various changes and modifications obvious to one skilled in the art to which the present invention pertains are deemed to be within the spirit, scope and contemplation of the present invention as further defined in the appended claims.

Referring to Figure 1, there is shown one of the preferred embodiments of the present invention protocol system 10 for digital stored voice message paging systems. The present invention protocol system 10 includes a multiplicity of frames. Each frame contains a short message section 12 and a voice data section 14. Each section consists of a plurality of packets. For example, in a particular embodiment of the present invention protocol system 10, the short message section 12 may have 202 packets and the voice data section 14 may have 2720 packets. In this embodiment, though it is by no means required, all packets have the same number of symbols.

The short message section 12 further contains alert packets, pointer packets and housekeeping or customized packets. One of the unique features of the present invention protocol is that the short message section coptains repeated pointer packets for a particular cycle. For example, as shown in Figure 1, the short message section 12 contains alert N (80 packets), pointer N (10 packets), alert N+1 (80 packets), pointer N+1 (20 packets), pointer N (10 packets) again, and housekeeping or customized packets (2 packets).

As further shown in Figure 1, in the present invention protocol 10, each alert packet 16 contains a pilot field (4 symbols), a group LD field (4 symbols), a system LD field (12 bits), an alert bit field (206 bits), and one or more customized fields.

Referring to Figure 2, there is shown a pointer packet 18 of the short message section of a frame of one of the preferred embodiments of the present invention protocol for digital stored voice message paging systems. The pointer packet 18 contains a pilot field (4 symbols), a group ID field (4 symbols), a system ID field (12 bits), multiple message pointer blocks (2065 bits), and one or more customized fields.

Each of the message pointer blocks consists of 29 bits of destination address and message description information.

Referring to Figure 3, there is shown the housekeeping or customizing packets of the preferred embodiments of the present invention protocol for digital stored voice message paging systems. For example, each housekeeping or customized packet contains a pilot (4 symbols), a group ID (4 symbols), a system ID (12 bits), data fields (206 bits), and one or more customized fields. Referring to Figure 4, there is shown the voice data stream header 20 of the voice data section 14 of a frame of one of the preferred embodiments of the present invention protocol. The voice data stream header 20 contains a stream ID (8 bits), a message number count (8 bits), stream message description blocks 22 (104 bits), and one or more customized fields.

Each message block 22 contains 112 bits of destination address and massage description data to aid the receiver in locating the message within the voice data stream.

Referring to Figure 5, there is shown the unique mapping of the voice data streams in the voice data section of a frame of one of the preferred embodiments of the present invention protocol.

The operation of the digital stored voice message paging system under the present invention protocol is as follows. The present invention protocol differs from the prior art protocols in that the alerting message is a single bit for each receiver. These bits are contained in an error corrected packet of similar alerting bits. The bit position within the packet is uniquely assigned to a particular receiver unit. If a receiver is not alerted by having its assigned bit set, it returns to the dormant state, and has expended only the energy required to decode and verify a single packet whose length may vary with the particular characteristics of the individual system.

Alerted receivers will go to a low-power or OFF state, and re-activate to receive a message definition packet or packets following the alerting packets. These packets are comprised of blocks which contain the destination receiver address and data to direct the receiver to the location of the message within the voice data section of the frame corresponding to the position of the pointer section in which they are located. Receivers thus directed will then return to the dormant state until the transmission time of their respective messages arrives.

A particularly vexing problem with mobile and portable simplex receivers is that they may move through areas of poor reception quality or experience several types of channel fading which may make reception difficult or impossible. In voice paging this problem is considerably aggravated because the voice messages are highly compressed and are therefore very sensitive to degradation from missing message bits. Conventional paging systems transmit rather short messages, but the longer messages in the voice system pose different problems. Forward error correction can help many poor reception situations, but is often insufficient for reliable voice reproduction due to the length or the severity of the fading. This situation may be greatly improved by providing signal diversity either in the frequency, geographical, or time domain. The present invention protocol adds significant time diversity to the system in several ways.

First, the alerting and message definition packets are sent twice, at the beginning of subsequent time frames. A group of alerts for the immediately following message period is directly preceded by a group of alerts for the next message period. This sequentially first group then becomes the second group in the following time frame. Such repetition gives each receiver two chances, separated by sufficient time that fading conditions may have altered, to receive the alerting messages.

Similarly, the message definition, or pointer packets, are repeated in the same manner and order as that of the alerting packets. The receiver need not activate for the second set of alerts if it successfully received the first. It simply waits for the assigned message stream to begin.

Additionally, the digitized voice message itself is subdivided into packets, each with a synchronizing mark at the beginning of each packet. This mark will aid in maintaining phase lock during certain types of channel fading. The data are assigned to a particular voice data stream, interleaved at the bit level across the entire stream, into packets. The packets are then interspersed with those of the other streams and are transmitted in scattered form throughout the length of the message time period. When reconstructed in the decoded, de- interleaved message, the bits which were transmitted adjacent to one another will be separated, and groups of errors in the transmission layer will appear scattered, facilitating the error correction process. This implementation differs from conventional interleaving schemes in that the bits of a particular message appear interleaved within each packet, but the packets containing the message bits are discontinuously placed throughout the message space. This placement allows the paging receivers to de-activate between packets in order to save power while still spreading the bits of each message throughout the relatively long message delivery period.

In the preferred embodiment, the packets of one message stream scattered through the transmission layer would not be uniformly spaced apart in time, but rather would have a pseudo-random spacing to avoid the prospect of becoming synchronized with a periodic channel fading phenomenon.

Another preferred embodiment of the present invention protocol would also transmit the starting location within the data stream of each message in the message definition packets to avoid the necessity of computing it in the receiver units.

Defined in detail, the present invention is a protocol for a digital stored voice paging system, comprising: (a) a multiplicity of limited frames each containing a short message section and a voice data section; (b) said short message section further containing a plurality of packets, including packets for an earlier alert, packets for a pointer for the earlier alert, packets for a subsequent alert, packets for a subsequent pointer for the subsequent alert, and packets for repeating the pointer for the earlier alert, wherein the repeating of the pointer for the earlier alert provides time diversity to reduce errors in voice message transmissions; and (c) said voice data section further containing a plurality of packets, including packets for voice data streams which are interspersed with one another and transmitted in scatter form throughout the length of the message time period; (d) whereby the operation of the protocol improves the power consumption and voice message transmission quality of the digital stored voice paging system.

Defined broadly, the present invention is a protocol for a digital stored voice paging system, comprising: (a) a multiplicity of limited frames each containing a short message section and a voice data section; (b) said short message section further containing a plurality of packets, including packets for repeated alerts at different times; and (c) said voice data section further containing a plurality of packets, including packets for voice data streams; (d) whereby the operation of the protocol improves the power consumption and voice message transmission quality of the digital stored voice paging system.

Alternatively defined broadly, the present invention is a protocol for a digital stored voice paging system, comprising: (a) a multiplicity of limited frames each containing a short message section and a voice data section; (b) said short message section further containing a plurality of packets, including packets for message alerts; and (c) said voice data section further containing a plurality of packets, including packets for voice data streams which are interspersed with one another and transmitted in scatter form throughout the length of the message time period; (d) whereby the operation of the protocol improves the power consumption and voice message transmission quality of the digital stored voice paging system.

Of course the present invention is not intended to be restricted to any particular form or arrangement, or any specific embodiment disclosed herein, or any specific use, since the same may be modified in various particulars or relations without departing from the spirit or scope of the claimed invention hereinabove shown and described of which the apparatus shown is intended only for illustration and for disclosure of an operative embodiment and not to show all of the various forms or modification in which the present invention might be embodied or operated.

The present invention has been described in considerable detail in order to comply with the patent laws by providing full public disclosure of at least one of its forms. However, such detailed description is not intended in any way to limit the broad features or principles of the present invention, or the scope of patent monopoly to be granted.

Claims

WHAT IS CLAIMED IS:

1. A protocol for a digital stored voice paging system, comprising: a. a multiplicity of limited frames each containing a short message section and a voice data section; b. said short message section further containing a plurality of packets, including packets for an earlier alert, packets for a pointer for the earlier alert, packets for a subsequent alert, packets for a subsequent pointer for the subsequent alert, and packets for repeating the pointer for the earlier alert, wherein the repeating of the pointer for the earlier alert provides time diversity to reduce errors in voice message transmissions; and c. said voice data section further containing a plurality of packets, including packets for voice data streams which are interspersed with one another and transmitted in scatter form throughout the length of the message time period; d. whereby the operation of the protocol improves the power consumption and voice message transmission quality of the digital stored voice paging system.

2. The protocol as defined in Claim 1 wherein each alert packet comprises a pilot field, a group identification field, a system identification field and an alert field.

3. The protocol as defined in Claim 1 wherein each alert packet further comprises one or more customized fields.

4. The protocol as defined in Claim 1 wherein said alerting packets are arranged in a manner to indicate by their sequence to which of said interspersed voice data streams a particular alert message corresponds.

5. The protocol as defined in Claim 1 wherein said short message section further comprises two or more repetitions of said subsequent alert.

6. The protocol as defined in Claim 1 further comprising a single bit alerting message assigned for each receiver in the digital stored voice paging system.

7. The protocol as defined in Claim 1 wherein said pointer packets include a pilot field, a group identification field, a system identification field, and message pointer blocks.

8. The protocol as defined in Claim 7 wherein the voice data packets of the streams are interspersed with one another such that the spacing between successive packets of the same stream is irregular and non-uniform.

9. The protocol as defined in Claim 5 wherein said housekeeping packet further comprises a pilot field, a group identification field, a system identification field and a housekeeping data field.

10. The protocol as defined in Claim 9 wherein said housekeeping packet further comprises one or more customized fields.

11. The protocol as defined in Claim 1 wherein each said voice data stream header packet comprises a stream identification field, a message number count field, and a plurality of stream message description blocks.

12. The protocol as defined in Claim 11 wherein each said voice data stream header packet further comprises one or more customized fields.

13. The protocol as defined in Claim 11 wherein each said stream message description block further comprises an address field, a message stream start field, and a message length field.

14. A protocol for a digital stored voice paging system, comprising: a. a multiplicity of limited frames each containing a short message section and a voice data section; b. said short message section further containing a plurality of packets, including packets for repeated alerts at different times; and c. said voice data section further containing a plurality of packets, including packets for voice data streams; d. whereby the operation of the protocol improves the power consumption and voice message transmission quality of the digital stored voice paging system.

15. The protocol as defined in Claim 14 wherein each alert packet comprises a pilot field, a group identification field, a system identification field and an alert field.

16. The protocol as defined in Claim 14 further comprising assigning alerting message to a single bit for each receiver in the digital stored voice paging system.

17. The protocol as defined in Claim 14 wherein the voice data packets of the streams are interspersed with one another such that the spacing between successive packets of the same stream is irregular and non-uniform.

18. A protocol for a digital stored voice paging system, comprising: a. a multiplicity of limited frames each containing a short message section and a voice data section; b. said short message section further containing a plurality of packets, including packets for message alerts; and c. said voice data section further containing a plurality of packets, including packets for voice data streams which are interspersed with one another and transmitted in scatter form throughout the length of the message time period; d. whereby the operation of the protocol improves the power consumption and voice message transmission quality of the digital stored voice paging system.

19. The protocol as defined in Claim 18 further comprising a single bit alerting message assigned for each receiver in the digital stored voice paging system.

20. The protocol as defined in Claim 18 wherein the voice data packets of the streams are interspersed with one another such that the spacing between successive packets of the same stream is irregular and non-uniform.

21. A method of improving the power consumption and/or voice message transmission quality of a digital stored voice paging system, comprising: a. transmitting a multiplicity of limited frames each containing a short message section and a voice data section; b. wherein said transmitting step includes transmitting a plurality of packets, including packets for an earlier alert, packets for a pointer for the earlier alert, packets for a subsequent alert, packets for a subsequent pointer for the subsequent alert, and packets for repeating the pointer for the earlier alert, wherein the repeating of the pointer for the earlier alert provides time diversity to reduce errors in voice message transmissions; and c. wherein said transmitting step further includes transmitting a further plurality of packets, including packets for voice data streams which are interspersed with one another, and being transmitted in scatter form throughout the length of the message time period.

22. A method of improving the power consumption and /or voice message transmission quality of a digital stored voice paging system, comprising: a. transmitting a multiplicity of limited frames each containing a short message section and a voice data section; b. transmitting a plurality of packets, including packets for repeated alerts at different times, said plurality of packets forming said short message section; and c. transmitting a further plurality of packets, including packets for voice data streams, said further plurality of packets forming said voice data section.

23. A method of improving the power consumption and/or voice message transmission quality of a digital stored voice paging system, comprising: a. transmitting a multiplicity of limited frames each containing a short message section and a voice data section; b. transmitting a plurality of packets, including packets for message alerts, said plurality of packets providing said short message section; and c. transmitting a further plurality of packets, including packets for voice data streams which are interspersed with one another and are transmitted in scatter form throughout the length of the message time period, said further plurality of packets providing said voice data section.