Method and apparatus for transferring isocronous data within a wireless computer network

• US 6,891,822 B1
• Filed: 09/08/2000
• Issued: 05/10/2005
• Est. Priority Date: 09/08/2000
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: ShareWave, Inc. (Cirrus Logic Incorporated)
• Inventors: Gubbi, Rajugopal R., EKAMBARAM, NATARAJAN, Goss, Steven
• Primary Examiner(s): PHAN, MAN U
• Application Number:
  US09/657,673
• Time in Patent Office: 1,705 Days
• Field of Search: 370/245, 370/280, 370/336, 370/337, 370/330, 370/345, 370/349, 370/437, 370/350, 370/347, 370/209, 370/342, 370/335, 375/133, 375/295, 375/354, 375/362, 375/364
• US Class Current: 370/345
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation

Abstract

A communication protocol includes a hierarchical arrangement of time slots within a communication channel for transmission and reception of isochronous data (e.g., video, audio, etc.) between components of a computer network. One of the time slots may include a window for transmission of keyboard and/or cursor control data from a client unit to a server, for example as a series of past and present keyboard and/or cursor control entries, with these entries being accompanied by a counter value indicative of the number of new entries since a previous transmission. Audio rate control information may also be transmitted from the client unit to the server during the reverse time slot and may be used by the server to determine the amount of audio information to be transmitted to the client unit in a subsequent forward time slot transmission period. The audio rate control information is determined according to the amount of stored audio information at the client unit. The client unit transmits rate control information so as to ensure sufficient audio information will be available for synchronized playback with video information received from the server.

Claims

1. A communication protocol, for the transmission and reception of isochronous video and audio data between components of a computer network, the protocol comprising a hierarchical arrangement of time slots within a communication channel, the hierarchical arrangement of time slots including a forward time slot and a reverse time slot which together define transmission and reception periods for a server and a client unit in the computer network, wherein video and audio data is transmitted from the server to the client unit during a forward time slot and audio rate control information is transmitted from the client unit to the server during the reverse time slot, the audio rate control information being used by the server to determine an amount of audio information to be transmitted to the client unit in a subsequent forward time slot so as to ensure sufficient audio information will be available for synchronized playback with associated video information received from the server.

2. The communication protocol of claim 1 wherein at least one of the time slots comprises a window for transmission of keyboard or cursor control data from the client unit to the server.

3. The communication protocol of claim 2 wherein at least one time slot in each of a forward and a reverse direction is reserved for control information passed between the components of the computer network.

4. The communication protocol of claim 2 wherein the keyboard or cursor control data is transmitted as a series of past and present keyboard or cursor control entries.

5. The communication protocol of claim 4 wherein the past and present keyboard or cursor control entries are accompanied by a counter value indicative of the number of new entries since a previous transmission.

6. The communication protocol of claim 5 wherein the communication channel communicatively couples the server with the client unit and comprises a number of time slots, the size of which are dynamically changeable according to operating conditions within the computer network.

7. The communication protocol of claim 1 wherein the sizes of the time slots are dynamically changeable according to the operating conditions of the computer network.

8. The communication protocol of claim 1 wherein the audio rate control information is determined according to the amount of stored audio information at the client unit.

9. The communication protocol of claim 1 wherein the audio information is stored in an audio information buffer at the client unit.

10. The communication protocol of claim 8 wherein the amount of audio information stored at the client unit is measured against preestablished thresholds.

11. The communication protocol of claim 1 wherein the video information is transmitted during forward time slot transmission periods.

12. The communication protocol of claim 11 wherein the video information is compressed using a variable rate compression scheme according to available bandwidth within the communication channel.

13. The communication protocol of claim 12 wherein the audio information is compressed using ADPCM.

14. The communication protocol of claim 11 wherein the amount of video information transmitted during forward time slot transmission periods depends upon the amount of audio information transmitted during such transmission periods.

15. A network for the transmission and reception of isochronous video and audio data, comprising:

a server;

a client unit; and

a wireless communication link communicatively coupling the server with the client unit according to a communication protocol that includes a number of time periods in a hierchical arrangement within a communications channel, wherein the client unit transmits audio rate control information to the server during a first reverse time period and the server transmits audio information to the client unit during a second forward time period, wherein the amount of audio information transmitted to the client unit by the server is determined responsive to the audio rate control information transmitted from the client unit to the server so as to ensure sufficient audio information will be available for synchronized playback with associated video information received from the server.

16. The network of claim 15 wherein keyboard or cursor control data is transmitted from the client unit to the server over the wireless communication link.

17. The network of claim 16 wherein the keyboard or cursor control data is transmitted as a series of past and present keyboard or cursor control entries.

18. The network of claim 17 wherein the past and present keyboard or cursor control entries are accompanied by a counter value indicative of the number of new entries since a previous transmission.

19. The network of claim 15 wherein the time periods comprise forward time slots to accommodate transmissions by the server to the client unit and reverse time slots to accommodate transmissions from the client unit to the server, each forward and reverse time slot including one or more frames of data including multimedia information.

20. The network of claim 15 wherein the client unit comprises a processor, a video decompression agent, an audio decompression agent and a keyboard agent.

21. The network of claim 15 wherein the server comprises a software stack which includes (a) a network stack performing transport functionality (b) one or more application agents, (c) a media communication agent, and (d) a host processor communication manager.

22. The network of claim 21 wherein information from the one or more application agents is utilized in making dynamic decisions regarding transmission slot sizes for data to be passed across the communication link.

23. A protocol for transmitting isochrronous audio and video data on a wireless network, the protocol comprising a plurality of frames within a communications channel and organized as a hierarchy of time slots, wherein each frame comprises:

a first forward time period for the transmission of audio and video data from a server to a client on the wireless network; and

a second reverse time period for the transmission of audio rate control information from the client to the server, wherein the client sends the audio rate control information to ensure it receives from the server sufficient audio data for synchronized playback of the audio data with the video data, wherein the server sends audio data to the client in the forward time period of a subsequent frame responsive to the audio rate control information received from the client so as to ensure sufficient audio information is transmitted to the client for synchronized playback of the audio data with the video data.

24. The protocol of claim 23 herein the plurality of frames are transmitted at a rate corresponding to a data rate of the video data.

25. The protocol of claim 24 wherein the audio data is buffered at the client.