Speech packet communication system and method
First Claim
1. A speech packet communication system in which two speech terminal means communicate speech signal packets to each other through a transmission line connected therebetween, said transmission line includes at least one intermediate switching node for controlling traffic of packets passing through the transmission line based on priority indicators assembled in each of the packets, each of said speech terminal means comprising:
- an encoder for converting an input speech signal to an encoded speech signal of a plurality of bits at a predetermined sample period;
a first packet assembler for preparing a first packet of the respective most significant bits of a plurality of encoded speech signals obtained in a frame interval of a plurality of sample period intervals, and for transmitting the first packet to the transmission line;
a second packet assembler for preparing a second packet of the respective least significant bits of the plurality of encoded speech signals obtained in the frame interval and for transmitting the second packet to the transmission line;
a speech detector for detecting a first parameter indicative of whether each of the encoded speech signals encoded during the frame interval belongs to an active speech region or a silent region, and for detecting a second parameter indicative of whether each of the encoded speech signals encoded at said predetermined sample period belongs to a front-end region, a hangover region of another region if the encoded speech signal belongs to an active speech region; and
a priority assignment unit for determining first and second priority indicators to be assembled into first and second packets respectively in accordance with the first and second parameters detected by the speech detector,wherein the first packet assembler assembles the first priority indicator into the first packet while the second packet assembler assembles the second priority indicator into the second packet.
0 Assignments
0 Petitions
Accused Products
Abstract
A speech packet communication system for making speech communication among a plurality of speech terminals and including a communication network. The communication network includes a transmission path and a plurality of intermediate switching nodes, each controlling the traffic of a plurality of speech packets received from the transmission path or other intermediate switching nodes in accordance with priority indicators contained in the respective packets. Each speech terminal converts the input speech signal to packets, transmits the packets onto the transmission path or decodes speech packets received from the transmission path. Particularly, when the terminal converts the input speech signal to packets, it uses a special purpose function of determining a priority indicator assigned to the packet to greatly improve the quality of a reproduced speech at a receiving end.
110 Citations
28 Claims
-
1. A speech packet communication system in which two speech terminal means communicate speech signal packets to each other through a transmission line connected therebetween, said transmission line includes at least one intermediate switching node for controlling traffic of packets passing through the transmission line based on priority indicators assembled in each of the packets, each of said speech terminal means comprising:
-
an encoder for converting an input speech signal to an encoded speech signal of a plurality of bits at a predetermined sample period; a first packet assembler for preparing a first packet of the respective most significant bits of a plurality of encoded speech signals obtained in a frame interval of a plurality of sample period intervals, and for transmitting the first packet to the transmission line; a second packet assembler for preparing a second packet of the respective least significant bits of the plurality of encoded speech signals obtained in the frame interval and for transmitting the second packet to the transmission line; a speech detector for detecting a first parameter indicative of whether each of the encoded speech signals encoded during the frame interval belongs to an active speech region or a silent region, and for detecting a second parameter indicative of whether each of the encoded speech signals encoded at said predetermined sample period belongs to a front-end region, a hangover region of another region if the encoded speech signal belongs to an active speech region; and a priority assignment unit for determining first and second priority indicators to be assembled into first and second packets respectively in accordance with the first and second parameters detected by the speech detector, wherein the first packet assembler assembles the first priority indicator into the first packet while the second packet assembler assembles the second priority indicator into the second packet. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. Speech packet communication system in which two speech terminal means communicate speech signal packets to each other through a transmission line connected therebetween, said transmission line includes at least one intermediate switching node for controlling traffic of packets passing through the transmission line based on priority indicators assembled in each of the packets, each of said speech terminal means comprising:
-
an encoder for converting an input speech signal to an encoded speech signal of a plurality of bits at a predetermined sample period; a first packet assembler for preparing a first packet of bits indicative of characteristic portions of respective speech signals of a plurality of encoded speech signals obtained in a frame interval of a plurality of sample period intervals and for transmitting the first packet to the transmission line; a second packet assembler for preparing a second packet of bits indicative of concomitant portions of the respective speech signals of the plurality of encoded speech signals obtained in the frame interval and for transmitting the second packet to the transmission line; and a priority assignment unit for determining first and second priority indicators to be assembled into the first and second packets in accordance with the nature of the speech signal input during the frame interval; wherein the first packet assembler assembles the first priority indicator into the first packet and wherein the second packet assembler assembles the second priority indicator into the second packet. - View Dependent Claims (9, 10, 11, 12)
-
-
13. A speech transmitting terminal for preparing speech packets from an input speech signal being supplied thereto and for transmitting the speech packets to a receiving terminal via at least one intermediate switching node which controls traffic of the packets passing therethrough based on priority indicators assembled in each of the packets, comprising:
-
an encoder for converting an input speech to an encoded speech signal of a plurality of bits at a predetermined sample period; a first packet assembler for preparing a first packet of bits, indicative of characteristic portions of respective speech signals of a plurality of encoded speech signals obtained in a frame interval of a plurality of sample period intervals and for transmitting the first packet to the intermediate switching node; a second packet assembler for preparing a second packet of bits, indicative of concomitant portions of the speech signals, of the plurality of encoded speech signals obtained in the frame interval and for transmitting the second packet to the intermediate switching node; and a priority assignment unit for determining first and second priority indicators to be assembled into the first and second packets in accordance with the nature of the speech signal input during the frame interval, wherein the first packet assembler assembles the first priority indicator into the first packet and wherein the second packet assembler assembles the second priority indicator into the second packet. - View Dependent Claims (14, 15, 16, 17)
-
-
18. A speech packet communication system in which two speech terminal means communicate speech signal packets to each other through a transmission line connected therebetween, said transmission line includes at least one intermediate switching node for controlling traffic of packets passing through the transmission line based on a priority indicator assembled in each of the packets, each of said speech terminal means comprising:
-
a subtractor for determining a difference between first and second signals respectively received by first and second input lines connected thereto and outputting the difference as a differential signal, wherein one of the input lines receives an input speech signal; an encoder for converting the differential signal to an encoded speech signal of bits; control signal generating means for generating a mean level signal from said differential signal and for comparing said mean level signal and a predetermined threshold to generate a control signal; prediction signal generating means for selecting between a first mode for preparing a prediction signal from the respective most significant bits of a plurality of encoded speech signals output from the encoder and a second mode for preparing a prediction signal from all the bits of the plurality of encoded speech signals in accordance with the control signal and outputting the prediction signal generated by the selected mode, wherein the prediction signal is supplied to the second input line of the subtractor as the second signal; a first packet assembler for preparing a first packet from respective most significant bits of a plurality of encoded speech signals obtained in one frame interval and for transmitting the first packet to the transmission line; and a second packet assembler for preparing a second packet from respective least significant bits of the plurality of encoded speech signals obtained in the one frame interval and for transmitting the second packet to the transmission line; and an assignment unit for determining first and second priority indicators to be assembled into the first and second packets in accordance with the control signal and a signal indicative of whether the speech signal input in the one frame interval belongs to an active speech region or a silence region, wherein the first packet assembler assembles the first priority indicator into the first packet and wherein the second packet assembler assembles the second priority indicator into the second packet. - View Dependent Claims (19, 20, 21)
-
-
22. A speech transmitting terminal for preparing speech packets from an input speech signal being supplied thereto and transmitting the speech packets to a receiving terminal via at least one intermediate switching node which controls traffic of packets passing therethrough based on priority indicators assembled in each of the packets, comprising:
-
a subtractor for determining a difference between first and second signals respectively received by first and second input lines connected thereto and outputting the difference as a differential signal, wherein said first input line receives an input speech signal as said first signal; an encoder for converting the differential signal to an encoded speech signal of bits; control signal generating means for generating a mean level signal from said differential signal and for comparing the mean level signal and a predetermined threshold to generate a control signal; prediction signal generating means for selecting between a first mode for generating a prediction signal from the respective most-significant bits of a plurality of encoded speech signals output from the encoder and a second mode for generating a prediction signal from all the bits of the plurality of encoded speech signals in accordance with the control signal and outputting the prediction signal generated by the selected mode, wherein the prediction signal is supplied to said second input line of the subtractor as said second signal; a first packet assembler for preparing a first packet from respective most significant bits of a plurality of encoded speech signals obtained in one frame interval and for transmitting the first packet to the transmission line; a second packet assembler for preparing a second packet from respective least significant bits of the plurality of encoded speech signals obtained in the one frame interval and for transmitting the second packet to the transmission line; and an assignment unit for determining first and second priority indicators to be assembled into the first and second packets in accordance with the control signal and a signal indicative of whether the speech signal input in the one frame interval belongs to an active speech region or a silence region, wherein the first packet assembler assembles the first priority indicator into the first packet and wherein the second packet assembler assembles the second priority indicator into the second packet. - View Dependent Claims (23, 24, 25)
-
-
26. A speech packet communication system in which two speech terminal means communicate speech signal packets to each other through a transmission line connected therebetween, said transmission line includes at least one intermediate switching node for controlling traffic of packets passing through the transmission line based on priority indicators assembled in each of the packets, each of said speech terminal means comprising:
-
a subtractor for determining a difference between first and second signals respectively received by first and second input lines connected thereto and outputting the difference as a differential signal, wherein said first input line receives an input speech signal as said first signal; an encoder for converting the differential signal to an encoded speech signal of bits; control signal generating means for generating a mean level signal from the differential signal and for comparing the mean level signal and a predetermined threshold to generate a control signal; prediction signal generating means for selecting between a first mode for generating a prediction signal from respective most significant bits of a plurality of encoded speech signals output from the encoder and a second mode for generating a prediction signal from all the bits of the plurality of encoded speech signals in accordance with the control signal and outputting the prediction signal generated by the selected mode, wherein the prediction signal is supplied to said second input line of said subtractor as said second signal; a first packet assembler for preparing a first packet from respective most significant bits of a plurality of encoded speech signals obtained in one frame interval and for transmitting the first packet to the transmission lines; a second packet assembler for preparing a second packet from respective least significant bits of the plurality of encoded speech signals obtained in the one frame interval and for transmitting the second packet to the transmission line; and an assignment unit for determining first and second priority indicators to be assembled into the first and second packets in accordance with the control signal and a parameter signal indicative of whether the speech signal input in the one frame interval belongs to an active speech region or a silence region, wherein the first packet assembler assembles the first priority indicator into the first packet, wherein the second packet assembler assembles the second priority indicator into the second packet and wherein the assignment unit selectively switches between a first mode for preparing respective packets from the most and least significant bits of a plurality of encoded speech signals obtained in the one frame interval and a second mode for preparing respective packets from bits of the former and latter halves of the one frame interval in accordance with the control signal and the parameter signal. - View Dependent Claims (27, 28)
-
Specification