Dynamic Wireless Channel Selection And Protocol Control For Streaming Media
Dynamic wireless channel selection and protocol control for streaming video utilizing transmission delay/packet loss information and channel utilization statistics. A transmission delay and packet loss monitor generates transmission delay information during the transmission of a video stream to remote wireless device(s) over a first wireless channel by timestamping and monitoring video packet(s) and associated transmission acknowledgement(s). The transmission delay information is compared to a predetermined threshold (e.g., a maximum tolerated delay threshold and/or total packet loss threshold) and, if the threshold is exceeded, a second wireless channel is selected for continued transmission of the video stream. In one mode, channel utilization statistics are likewise examined prior to a channel relocation event. Selection of the second wireless channel may be accomplished through a random or semi-random channel selection process, or through active scanning to collect clear channel assessment statistics for candidate channels. In another mode, at least one transmission protocol parameter is altered in response to a violation of one or more of the predetermined thresholds.
1 . A method for use in a wireless access device during the transmission, over a first wireless channel, of a video stream, the method comprising:
monitoring a transmit queue of the wireless access device to generate transmission delay information for packets of the video stream transmitted over the first wireless channel;
comparing the transmission delay information to a predetermined threshold(s); and
triggering selection of a second wireless channel for further transmission of the video stream if the transmission delay information exceeds the predetermined threshold(s).
2 . The method of claim 1 , wherein the step of monitoring a transmit queue comprises:
marking a video packet(s) with an indication of the time the respective video packet(s) is submitted for transmission by the wireless access device;
receiving at least one of associated transmission acknowledgment and packet expiration information for the video packet(s);
calculating transmission delays for the video packet(s) by comparing the indication of the time the respective video packet(s) is submitted for transmission with the associated transmission acknowledgment information and/or packet expiration information; and
generating transmission delay information based on the calculated transmission delays.
3 . The method of claim 2 , further comprising:
generating a completion timestamp relating to the transmission acknowledgment and/or packet expiration information, and wherein the step of calculating transmission delays for the video packets comprises comparing the indication of the time a video packet is submitted for transmission with the timestamp.
4 . The method of claim 1 , wherein the step of selecting a second wireless channel occurs on a periodic basis, and wherein the threshold(s) value(s) are established such that transmission delay information in excess of the threshold(s) value(s) is indicative of potential difficulties in transmission of the video stream.
5 . The method of claim 4 , wherein the predetermined threshold(s) is at least one of a maximum tolerated delay threshold and a total packet loss threshold.
6 . The method of claim 4 , wherein the threshold(s) value(s) are adjustable in response to at least one of PHY characteristics, transmission protocol parameters, communication protocol parameters, and channel and reception characteristics relating to the wireless channel.
7 . The method of claim 1 , further comprising
analyzing the first wireless channel to generate channel utilization statistics; and
comparing the channel utilization statistics to a second predetermined threshold(s), wherein the step of triggering selection of a second wireless channel is further dependent on a determination that the channel utilization statistics exceed the second predetermined threshold(s).
8 . The method of claim 7 , wherein the channel utilization statistics indicate channel utilization by at least one of transmissions from other devices and other energies in the first wireless channel.
9 . The method of claim 7 , wherein the channel utilization statistics comprise counter values indicating the duration of detected transmissions from other devices sharing the first wireless channel.
10 . The method of claim 1 , further comprising
identifying a second wireless channel;
transmitting a channel switch announcement, the announcement including an identification of the second channel;
receiving an acknowledgment of the channel switch announcement; and
continuing transmission of the video stream utilizing the second wireless channel.
11 . The method of claim 10 , wherein resuming transmission of the video stream comprises directing the first transmitted frame of the video stream to be an intra-coded frame.
12 . The method of claim 10 , the wireless access device operable with a plurality of supported wireless channels, wherein identifying a second wireless channel comprises:
selecting a random wireless channel from the group of supported wireless channels;
monitoring the random wireless channel to generate associated channel utilization statistics; and
comparing the associated channel utilization statistics to a predetermined threshold(s), and wherein transmission of the video stream is continued on the random wireless channel if the associated utilization statics are below the predetermined threshold(s).
13 . The method claim 10 , the wireless access device operable with a plurality of supported wireless channels, wherein identifying a second wireless channel comprises:
scanning individual channels of the plurality of supported wireless channels to collect clear channel assessment statistics for the individual channels; and
comparatively analyzing the clear channel assessment statistics to select a second wireless channel from the plurality of supported wireless channels.
14 . A method for use in a wireless access device during the transmission, over a first wireless channel, of a video stream, the method comprising:
monitoring a transmit queue of the wireless access device to generate transmission delay information for packets of the video stream transmitted over the first wireless channel;
comparing the transmission delay information to a predetermined threshold(s);
triggering selection of a second wireless channel for further transmission of the video stream if the transmission delay information exceeds the predetermined threshold(s); and
altering at least one protocol parameter of the second wireless channel.
15 . The method of claim 14 , the at least one protocol parameter comprising at least two of slot assignment parameters, transmit power allocation parameters, beam forming parameters, MIMO parameters, channel coding/block coding parameters, frequency band assignment parameters, packet length parameters, data rate parameters, forward error correction parameters, error detection parameters, contention period parameters, and back-off parameters.
16 . An apparatus, comprising:
a network interface for supporting transmission of a packetized video stream over a wireless channel of a plurality of supported wireless channels, the network interface comprising a transmit queue; and
a channel selection module operable to dynamically control selection of the wireless channel by:
monitoring the transmit queue of the network interface to generate transmission delay information for packets of the video stream transmitted over a first wireless channel;
comparing the transmission delay information to a predetermined threshold(s); and
triggering selection of a second wireless channel for further transmission of the video stream if the transmission delay information exceeds the predetermined threshold(s).
17 . The apparatus of claim 16 , wherein monitoring the transmit queue comprises:
marking a video packet(s) with an indication of the time the respective video packet(s) is submitted for transmission by the network interface;
receiving at least one of associated transmission acknowledgment and packet expiration information for the video packet(s);
calculating transmission delays for the video packet(s) by comparing the indication of the time the respective video packet(s) is submitted for transmission with the associated transmission acknowledgment information and/or packet expiration information; and
generating transmission delay information based on the calculated transmission delays.
18 . The apparatus of claim 17 , the channel selection module further operable to dynamically control selection of the wireless channel by:
analyzing the first wireless channel to generate channel utilization statistics; and
comparing the channel utilization statistics to a second predetermined threshold(s), wherein triggering selection of a second wireless channel is further dependent on a determination that the channel utilization statistics exceed the second predetermined threshold(s).
19 . The apparatus of claim 18 , wherein the channel utilization statistics indicate channel utilization by transmissions from other devices and other energies in the first wireless channel
20 . The apparatus of claim 18 , the channel selection module further operable by:
identifying a second wireless channel;
transmitting a channel switch announcement, the announcement including an identification of the second channel;
receiving an acknowledgment of the channel switch announcement; and
continuing transmission of the video stream utilizing the second wireless channel.