Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
2000-02-08
2001-10-09
Moise, Emmanuel L. (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C714S748000, C714S797000
Reexamination Certificate
active
06301681
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to communication protocols and more particularly to a communication protocol for transferring messaging information between a messaging server and a remote device over a communication network using an acoustically coupled modem.
Letters were once, and in some places still are, the sole method of long distant personal and business communication. Communication progressed through the telegraph period. The advent and proliferation of the telephone caused the telephone call to rival the letter as the preferred method of personal and business communication.
The Internet and widespread use of Personal Computers, led to electronic messaging, using a modem, as a popular method of communication for both personal and business uses. In effect, the letter and the telephone were combined. The Personal Computer produced the electronic message, i.e., letter, and this was transferred to the telephone network via a modem. Modems, which once were external and acoustical, are now embedded in Personal Computers, laptops, or Personal Digital Assistants.
However, these modems typically need a telephone jack, are slow in establishing a connection to an electronic messaging server, and are frequently error prone in transferring data. One problem with today's modem technology is that most public access telephones do not have an external jack. Thus, a business traveler at an airport would have to search for an external jack, even though many public telephones may be available.
Conventional acoustically coupled modems attempted to solve this problem by providing an easy connection to a telephone handset wherein a connection to RJ-4 or RJ-11 jack was not required. These modems were external devices connected to the Personal Computer with an telephone cradle to hold a telephone headset. A typical modem would have muffs over the earpiece and the mouthpiece of the telephone handset to filter out external noise. This interface between the telephone handset and the modem had several disadvantages including: 1) the modem was bulky, and 2) despite the mechanical damping, it was susceptible to noise; hence data transfer was error prone. Little or no error correction was used. These problems led to the conventional acoustically coupled modem losing popularity in the market.
There are several other problems associated with conventional acoustically coupled computer modems. The connection phase of modem operation includes an extensive hand-shaking procedure. The error detection and retransmission mechanisms used during the data exchange phase are inadequate and error prone. The net effect is to prolong the time on the telephone and delay the sending and receiving of electronic messages between remote device and messaging server.
Therefore in the blossoming market of electronic messaging, there is a need for a remote device which can communicate with a remote messaging sever via a telephone network in an expedited and error-free manner. A portable, hand-held acoustically coupled modem is needed, that can be easily connected to any telephone. The acoustically coupled modem should provide a fast and reliable connection procedure, and perform fast, robust, and error free data transfer. A goal should be the minimization of total time on the telephone needed for connection, data transfer, and disconnection.
SUMMARY OF THE INVENTION
The present invention uses an acoustic modem embedded in a remote device enhanced with automatic repeat-request and forward-error-correction routines to provide reliable transfer of electronic messages from the messaging server to the remote device. Embodiments according to the present invention, provide a fast, reliable connection sequence by use of a preamble frame. This fast and reliable transfer of data can reduce the user wait time for receiving or sending messages. This can also reduce the time that the modem needs to be physically coupled to the telephone handset.
According to an embodiment of the present invention, a method of communicating messages between a messaging server and a remote device is provided. The method includes a variety of steps such as establishing a connection between the messaging server and the remote communication device by transmitting a preamble frame. A step of exchanging data frames between the remote device and the messaging server is also included. The method then includes a step of detecting and correcting errors in received frames. The method can also include the step of re-transmitting received frames, if errors are uncorrectable.
In another aspect of the present invention, a method for error detection and correction during an exchange of frames between a messaging server and a remote device is provided. The method includes a variety of steps such as analyzing the packet type code of a received frame for errors. The interleaved packet in the frame may be de-interleaved. A step of BCH decoding the de-interleaved encoded packet is also included. The method may perform erasure correction, if the original and retransmitted decoded packets have uncorrectable errors. Next a step may be performed of majority bit combining and BCH decoding, if there are at least two retransmissions, and the original and both the retransmitted decoded packets have uncorrectable errors. The method may analyze the CRC check bits on the correctable decoded packets with the parity bits removed. If in one or more of the above steps, uncorrectable errors are found, there may be a request for a re-transmission by sending a non-acknowledge (NAK) frame.
The electronic messaging system and method of the invention may have a remote device comprising: processors, storage devices, and a communication subsystem containing the modem, and a messaging server comprising: processors, storage devices, and a network interface subsystem which is connected to the telephone system.
A further understanding of the nature and advantages of the inventions herein may be realized by reference to the remaining portions of the specification and the attached drawings.
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Newshound Email Commands, Email commands and Description at http://www.hound.com/help/ecommandsdetails.htm.
Beerman Richard C.
Chen Zongbo
Koralek Richard W.
Korek Brian D.
Langill Wade
Moise Emmanuel L.
PocketMail Inc.
Townsend and Townsend / and Crew LLP
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