Patent Application
20120002103
This invention relates in general to wireless communications, and in particular, to improving Quality of Service (QoS) for wireless video transmissions.
Meeting QoS criteria for video transmission over wireless communication links is important for meeting user requirements. As an example, most television (TV) manufacturers require smooth video streaming over wireless links without any visual quality degradation for over 40 continuous hours. However, wireless communication links, such as wireless radio frequency channels in Wi-Fi and millimeter wave (mmW), can suffer from interference or blockage problems and encounter packet loss, resulting in increased communication latency and degrading QoS.
According to an embodiment of the invention, a system implementing a method for multi-band wireless communication packetizes a block of source video information into a first packet, and packetizes the block of source video information into a second packet corresponding to the first packet, wherein the first packet and the second packet include corresponding video information. The first packet and the second packet are transmitted from a transmitting multi-band wireless station comprising a first radio for communication over a first wireless band, and a second radio for communication over a second wireless band. The first packet is transmitted over the first wireless band and the second packet is transmitted over the second wireless band. The first wireless band operates at a higher transmission rate than the second wireless band. A multiband receiving wireless station reconstructs the source video based on packets arriving on different bands.
These and other features, aspects and advantages of the present invention will become understood with reference to the following description, appended claims and accompanying figures.
Embodiments of the invention provide a method and system for providing QoS for wireless video transmission using multi-band operation. According to an embodiment of the invention, a system implementing a method for multi-band wireless communication packetizes a block of source video information into a first packet, and packetizes the block of source video information into a second packet corresponding to the first packet, wherein the first packet and the second packet include corresponding video information. The first packet and the second packet are transmitted from a transmitting multi-band wireless station comprising a first radio for communication over a first wireless band, and a second radio for communication over a second wireless band. The first packet is transmitted over the first wireless band and the second packet is transmitted over the second wireless band. The first wireless band operates at a higher transmission rate than the second wireless band. A multi-band receiving wireless station reconstructs the source video based on packets arriving on different bands.
In one embodiment of the invention, wireless transmission between wireless devices (wireless stations) such as a transmitting wireless station and a receiving wireless station, comprises a multi-radio operation (e.g., first and second wireless bands, with the first wireless band providing a higher transmission rate than the second wireless band), to improve QoS for uncompressed and/or compressed wireless video transmission. For example, IEEE 802.11ad specifies fast session transfer (FST) mechanism for multi-band wireless devices which implies that an example IEEE 802.11ad compatible wireless device includes both a Wi-Fi radio (e.g., 2.4 GHz or 5 GHz band) and a mmW radio (e.g., 60 GHz band). In one embodiment, a frame structure is used for data transmission between wireless stations such as a transmitting station and a receiving station. In one example, a frame structure in a Media Access Control (MAC) layer and a physical (PHY) layer is utilized (such as in IEEE 802.11 standard), wherein in a transmitting station, a MAC layer receives a MAC Service Data Unit (MSDU) and attaches a MAC header thereto, in order to construct a MAC Protocol Data Unit (MPDU). The MAC header includes information such as a source address (SA) and a destination address (DA) for the receiving station. The MPDU is a part of a PHY Service Data Unit (PSDU) and is transferred to a PHY layer in the transmitting station to attach a PHY header (i.e., PHY preamble) thereto to construct a PHY Protocol Data Unit (PPDU). The PHY header includes parameters for determining a transmission scheme including a coding/modulation scheme. Before transmission as a frame from the transmitting station to the receiving station, a preamble is attached to the PPDU, wherein the preamble can include channel estimation and synchronization information. The PHY layer in the transmitting station and the receiving station includes transmission hardware for communication data bits over a wireless link.
In one embodiment of the invention, each wireless station includes a transceiver comprising both a Wi-Fi radio and a mmW radio. In one implementation, a transmitting wireless station (i.e., transmitter) transmits uncompressed high-definition video over a first wireless band such as mmW (e.g., ultra band or UB wireless channel) and simultaneously transmits compressed video of the same content, or partial information of the uncompressed video, over a second wireless band such as Wi-Fi in either 2.4 GHz or 5 GHz band (e.g., low band or LB, or high band or HB, wireless channel), to a receiving wireless station (i.e., receiver).
In one embodiment of the invention, both the UB and LB/HB radio frequency (RF) wireless channels are used for compressed video communication between the transmitter and the receiver. In one example, both UB and LB/HB wireless channels are used for synchronized transmission of the same video information from the transmitter to the receiver. In another example, a primary wireless channel is used for the compressed video transmission without acknowledgement (ACK) and re-transmission scheme, and a secondary wireless channel is used for ACK packet transmission and also re-transmission of erroneous or lost video packets (e.g., audio/video packets). For example, a LB/HB wireless channel is used as primary channel for compressed video transmission and a UB wireless channel is used as secondary channel for ACK transmission and re-transmission of the erroneous or lost video packets, or vice-versa.
In one embodiment of the invention in which the UB and HB/LB cannot operate in parallel (i.e., simultaneously), a switching module switches between uncompressed video and compressed video transmission in a synchronized manner utilizing a FST process at the MAC/PHY layers of the transmitter and receiver. In the context of the description herein, FST means the switching from one radio operation to another radio operation (e.g., from UB to LB/HB or from LB/HB to UB).
Referring to
According to an embodiment of the invention, communication of uncompressed video over the mmW channel and transmission of compressed video over the Wi-Fi channel is synchronized during transmission. Synchronization can be performed at different levels, for example, video frame level or video slice level. In one example, synchronization is achieved by using timestamps and the frame/slice numbers or packet numbers, as shown by an example timing diagram 30 in
Based on the timestamps, a receiving multi-band wireless station (receiver) can reconstruct said source content from the received packets. Specifically, the receiver matches the timestamps between packets on the two different channels (mmW and Wi-Fi) to identify packets that include corresponding source content. As such, two packets arriving on different channel wherein the packet have the same timestamp include corresponding video information (e.g., a first received packet includes uncompressed source video information and a second received packet includes a compressed version of said uncompressed source video information, or a first received packet includes compressed source video information and a second received packet includes the same compressed source video information, etc.). The receiver then reconstructs the source content based on the video information in one or more of the received video packets identified as having the same (i.e., matching) timestamps.
According to an embodiment of the invention, video encoding latency and video decoding latency are taken into consideration when scheduling the compressed video packets at the Wi-Fi channel for synchronization with the corresponding uncompressed video packets at the mmW channel. At the receiver side, the compressed video packets can be skipped without decoding if the corresponding uncompressed video packets at the mmW channel are successfully received. No re-transmission is needed for this scheme. According to an example of using latency for scheduling and synchronizing, if the timestamp is set to T and video decoding latency is Td, then there is a requirement for scheduling that the compressed video cannot arrive later than T-Td.
Referring to
Referring to
Referring to
Compression is performed before packetization. Typically, both the transmitter and receiver have memory buffers for the compressed video packets. Since the mmW channel is faster than the Wi-Fi channel, the video packet size at the mmW channel is larger than the video packet size at the Wi-Fi channel.
Referring to the synchronization timing diagram 80 in
Referring to the synchronization timing diagram 90 in
Referring to the synchronization timing diagram 100 in
In the above-described example schemes, in each wireless station two wireless radios (mmW and Wi-Fi) can operate simultaneously. In case the two wireless radios cannot operate simultaneously, a switching process between mmW radio operation and Wi-Fi radio operation can be synchronized using the FST process as described in the IEEE 802.11ad specification. The MAC layer instructs the PHY layer radio to switch between the mmW and Wi-Fi radios. The receiver may buffer a number of incoming packets during the switching process.
Referring to the process 110 in
The AP 201 and the stations 202 and 204 implement a frame structure that is used for data transmission therebetween, using packet transmission in a MAC layer and a PHY layer. In a typical AP, a MAC layer receives a data packet including payload data, and attaches a MAC header thereto, in order to construct a MPDU. The MAC header includes information such as a SA and a DA. The MPDU is a part of a PSDU and is transferred to a PHY layer in the AP to attach a PHY header (i.e., a PHY preamble) thereto to construct a PPDU. The PHY header includes parameters for determining a transmission scheme including a coding/modulation scheme.
The transmitter 202 includes an application layer 210, a MAC layer 208 and a PHY layer 206. The application layer 210 packetizes information, wherein the packets are then converted to MAC packets by the MAC layer 208. The application layer 210 may further send transmission requests and control commands to reserve wireless channel time blocks for transmission of packets.
The PHY layer 206 includes a Wi-Fi radio module 203, a mmW radio module 205 and a RF communication module 207. The RF communication module 207 transmits/receives signals under control of the radio modules 203 and 205. The PHY layer 206 may further include a baseband module.
The receiver 204 includes a PHY layer 214, a MAC layer 216 and an application layer 218. The PHY layer 214 includes a Wi-Fi radio module 215, a mmW radio module 217, and a RF communication module 213 which transmits/receives signals under control of the radio modules 215 and 217.
The application layer 218 de-packetizes information in the MAC packets, received by the MAC layer 216. The depacketizing is reverse of the packetization. The application layer 218 may further handle wireless channel access.
The MAC layers 208 and 216 include respective multi-band control modules 208A and 216A. The multi-band control module 208A implements multi-band control processes including compression, packetization, synchronization, band switching as needed, transmitting and retransmitting source video data using the Wi-Fi and mmW channels from the transmitting station 202, as described above. The multi-band control module 216A implements multi-band control processes including receiving said video data using the Wi-Fi and mmW channels, band switching as needed, sending back ACK/NACK to the transmitter for packet retransmission, and reconstructing the source video data from one or more arriving packets, as described above. In other embodiments, the multi-band control modules 208A and 216A could be implemented in the respective application layers 210 and 218 or in some combination of MAC layers 208 and 216 and application layers 210 and 218.
As is known to those skilled in the art, the aforementioned example architectures described above can be implemented in many ways, such as program instructions for execution by a processor, as software modules, microcode, as computer program product on computer readable media, as logic circuits, as application specific integrated circuits, as firmware, as consumer electronic devices, etc., in wireless devices, in wireless transmitters/receivers, in wireless networks, etc. The disclosed embodiments can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment containing both hardware and software elements.
Information transferred via communications interface 317 may be in the form of signals such as electronic, electromagnetic, optical, or other signals capable of being received by communications interface 317, via a communication link that carries signals and may be implemented using wire or cable, fiber optics, a phone line, a cellular phone link, an radio frequency (RF) link, and/or other communication channels. Computer program instructions representing the block diagram and/or flowcharts herein may be loaded onto a computer, programmable data processing apparatus, or processing devices to cause a series of operations performed thereon to produce a computer implemented process.
Embodiments of the present invention have been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. Each block of such illustrations/diagrams, or combinations thereof, can be implemented by computer program instructions. The computer program instructions when provided to a processor produce a machine, such that the instructions, which execute via the processor create means for implementing the functions/operations specified in the flowchart and/or block diagram. Each block in the flowchart /block diagrams may represent a hardware and/or software module or logic, implementing embodiments of the present invention. In alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures, concurrently, etc.
The terms “computer program medium,” “computer usable medium,” “computer readable medium”, and “computer program product,” are used to generally refer to media such as main memory, secondary memory, removable storage drive, a hard disk installed in hard disk drive. These computer program products are means for providing software to the computer system. The computer readable medium allows the computer system to read data, instructions, messages or message packets, and other computer readable information from the computer readable medium. The computer readable medium, for example, may include non-volatile memory, such as a floppy disk, ROM, flash memory, disk drive memory, a CD-ROM, and other permanent storage. It is useful, for example, for transporting information, such as data and computer instructions, between computer systems. Computer program instructions may be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.
Computer programs (i.e., computer control logic) are stored in main memory and/or secondary memory. Computer programs may also be received via a communications interface. Such computer programs, when executed, enable the computer system to perform the features of the present invention as discussed herein. In particular, the computer programs, when executed, enable the processor multi-core processor to perform the features of the computer system. Such computer programs represent controllers of the computer system.
Though the present invention has been described with reference to certain versions thereof; however, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.
This application claims priority to, and claims benefit of, U.S. Provisional Patent Application Ser. No. 61/360,830 filed on Jul. 1, 2010, incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61360830 | Jul 2010 | US |
