Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/64—Hybrid switching systems
  • H04L12/6418—Hybrid transport
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/64—Hybrid switching systems
  • H04L12/6418—Hybrid transport
  • H04L2012/6421—Medium of transmission, e.g. fibre, cable, radio, satellite
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/64—Hybrid switching systems
  • H04L12/6418—Hybrid transport
  • H04L2012/6445—Admission control
  • H04L2012/6456—Channel and bandwidth allocation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/64—Hybrid switching systems
  • H04L12/6418—Hybrid transport
  • H04L2012/6494—Silence suppression

Definitions

• This invention relates to packet voice transmission.
• Communications networks currently transfer vast quantities of information in both local and wide area networks.
• the information typically consists of signals representing digitized voice and video as well as data that are transferred between endpoints in networks.
• a communication path may be established in such networks by circuit switching or by packet switching.
• circuit switching an exclusive channel is established between a sender and a receiver throughout the entire transmission until the connection is released.
• packet switching virtual circuits or channels are established between a sender and a receiver and a channel is only occupied for the duration of the packet's transmission.
• Such packet switching enables networks to handle the heterogeneous mix of network traffic with varying service requirements and, ideally, packet switching is scalable and can reliably establish and maintain virtual channels without any prespecified rates (so-called bandwidth on demand).
• An improvement in the art is achieved with an arrangement where a certain minimum bandwidth is always maintained.
• the bandwidth that is allocated to the call is reduced.
• the reduced bandwidth remains in force, unless there is spare capacity, in which case a full measure of bandwidth is allocated to the call.
• FIG. 1 depicts one environment where the principles of this invention may be practiced
• FIG. 2 illustrates 5 signal frames, with slot 2 allocated to phone 10;
• FIG. 3 shows a communication interface chart for an arrangement where bandwidth needs are determined at the base station of the FIG. 1 arrangement
• FIG. 4 shows a communication interface chart for an arrangement where bandwidth needs are determined at the base station of the FIG. 1 arrangement.
• FIG. 1 shows a cellular telephony arrangement with a cell phone 10 communicating with base station 20 that includes conventional control circuitry for managing the bandwidth available to base station 20, and for managing the calls from various cellular phones, including phone 10.
• base station 20 that includes conventional control circuitry for managing the bandwidth available to base station 20, and for managing the calls from various cellular phones, including phone 10.
• a cell phone communicates with a base station over a specified 200 KHz channel that comprises frames, with eight slots per block and a given number of blocks per frame (e.g., 8).
• the base station sends a frame control signal to which all cell phones synchronize.
• the voice signal of phone 10 is illustratively encoded by a 13 Kbps coder that adds 9 kbps of error protection and thus develops a 22 kbps signal.
• FIG. 2 shows 5 frames, where slot 2 is allocated to phone 10.
• FIG. 3 shows the communication that takes place between phone 10 and base station 20 when base station 20 includes circuitry for detecting silence periods of a cell phone user.
• Line 11 represents the conventional protocol employed for establishing communication between cell phone 10 and base station 20. This includes the protocol that is engaged in when the cell phone requests service and/or when the cell phone is hailed by the base stations.
• base station 20 specifies to phone 10 the specific frequency channel and time slot that is available to it for sending packets upstream. Thereafter, two-way communication proceeds (line 13 in FIG. 3) with cell phone 10 sending information to the base station in accordance the FIG. 2 scheme, and base station 20 broadcasting its downstream packets. This is indicated by line 13 in FIG. 3.
• base station 20 has granted phone 10 its full due bandwidth; to wit, one out of eight time slots in each block of a frame.
• base station 20 monitors the signal of phone 10 to determine whether the user has entered a silence period.
• This monitoring might take one of two forms.
• the cell phone sends packets that represent whatever background noise exists at the microphone of phone 10, and base station 20 includes module 21 that base station 20 couples to the signal of phone 10.
• This equipment decodes the signal of cell phone 10 and ascertains whether that signal represents speech, or background noise.
• Module 21 is realized through conventional modules; for example, circuitry that measures the power contained in the signal.
• cell phone 10 includes conventional circuitry that detects when its user has entered a silence period and, in response thereto, stops radiating power (not unlike a voice- activated tape recorder).
• the power-measuring circuitry 21 within base station 20 has an easy time of detecting a silence period when the cell phone stops radiating power altogether.
• base station 20 detects a silence period associated with a phone that has a full bandwidth allocation, such as phone 10 in this example, in accordance with the principles disclosed herein that fact is communicated to control circuit 22, and circuit 22 sends a control message 14 to cell phone 10, instructing phone 10 that its allocated bandwidth has been reduced.
• phone 10 is instructed that only the even-numbered (or the odd- numbered) blocks of a frame, or some other specified fraction of the frame, are henceforth available to phone 10.
• This control message can have the format of the control message of line 12.
• the control message 12 might also instruct cell phone 10 to move to another time slot.
• the appropriated capacity is sufficient to satisfy the minimum needs of at least one other user, yet not so great as to impose an unduly poor Quality of Service (QoS) on cell phone 10.
• QoS Quality of Service
• the appropriated capacity might be Vz, or 3 ⁇ of the full bandwidth.
• base station 20 will use the channel capacity that was relinquished by phone 10, and appropriated by base station 20, for establishing communication for, or to, another cell phone, such as phone 23. It is noted that, in this case, phone 23 is operating at half bandwidth.
• the capacity relinquished by phone 10 by going into a silence period is not recovered by phone 10, except by the grace of base station 20. That is, when phone 10 exits its silence period it must encode the speech signal at the lower rate that comports with the specification of message 14. For the example above, if message 14 allots phone 10 only half the capacity, 11 Kbps are available (instead of the 22 Kbps) for communicating information to base station 10 and, thus, 6 Kbps might be used for voice coding, leaving 5 Kbps for error protection.
• base station 20 moves cell phone 23, freeing up the slots previously appropriated from cell phone 10. Thence, base station 20 sends command 16 to cell phone 10, instructing it to resume encoding in full bandwidth. If another full bandwidth time slot is available, base station 20 sends a message 16 to cell phone 10 instructing it to move to a new slot and to encode its speech signal in full bandwidth.
• Message 16 advantageously has the same general format of message 14. Once message 16 is received, phone 10 resumes communicating at the 22 Kbps rate.
• FIG. 4 shows the communication that takes place between phone 10 and base station 20 when base station 20 operates without module 21 and relies on phone 10 to detect periods of silence or non-silence.
• FIG. 4 is basically identical to FIG. 3, except that phone 10 is burdened with the need to inform base station 20 when it enters a silence period, and when it entered a non-silence period. This is depicted in FIG. 4 by messages 18 and 19, respectively.
• control circuitry 22 receives its information from the cell phone instead of from module 21 but, otherwise, the operation is the same.
• the above example discloses a simple schema for reducing the bandwidth; to wit, allotting every even (or odd) block of a frame for a phone in a silence period ( 1 capacity), or allotting every fourth block of a frame for a phone in a silence period ( capacity). It also discloses that the bandwidth that is left for the phone in a silence period should be not smaller than the minimum bandwidth that is needed by a real-time (e.g., voice) user. It further discloses that the bandwidth that is taken away from the phone in a silence period should be not smaller than the minimum bandwidth that is needed by a user. It should be recognized, however, that the first and the third of these illustrative suggestions are not required by the principles disclosed herein.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)
• Data Exchanges In Wide-Area Networks (AREA)
• Time-Division Multiplex Systems (AREA)

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• 2000
  • 2000-07-19 CA CA002379412A patent/CA2379412C/en not_active Expired - Fee Related
  • 2000-07-19 EP EP00947500A patent/EP1195031A1/de not_active Withdrawn
  • 2000-07-19 MX MXPA02000627A patent/MXPA02000627A/es active IP Right Grant
  • 2000-07-19 WO PCT/US2000/019620 patent/WO2001006721A1/en active Search and Examination

Non-Patent Citations (1)

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