Patent Grant
8498280
1. Field
The disclosure generally relates to communication networks and systems. In particular, the disclosure relates to systems and methods for reducing overhead data for frames or packets in communication networks and systems.
2. Background
Many forms of wireless communication systems and networks are used to transmit various forms of data including, but not limited to, voice, video, multimedia, and packet data. Such data are generally divided into “data frames” for transmission in wireless communications systems and networks. For example, a data file that is sent from a transmitter to a receiver may be divided into a plurality of frames. The frames may then be transmitted from the transmitter to the receiver. Once the receiver has received all of the frames, it may combine the frames to reconstruct the data file.
In addition, communication systems and networks may need command and/or control information to help maintain and manage communications between the transmitter and the receiver. Such command and/or control information may also be sent and received by placing the information in frames. Frames containing command information are generally referred to as “command frames.” The term “command frames” should be interpreted broadly and include, but is not limited to, frames used to establish and maintain communications between devices. Frames containing control information are generally referred to as “control frames.” The term, “control frames” should be interpreted broadly and includes, but is not limited to, frames that assist in the delivery of data frames between devices. In general, command and/or control frames are often shorter in length and have a smaller payload than data frames.
Each type of frame may comprise framing information including, but not limited to, a preamble, header information, error checking information, and padding information, and may require inter-frame spacing. This framing information may be used by the communication system to transmit, receive, decode and combine the frames. The command and/or control frames may be transmitted in separate frames. Because there is a minimum overhead associated with transmitting a frame, that amount of overhead may be greater than the amount of actual command or control information itself. This may result in wasted overhead when transmitting command and/or control frames. Thus, it is desirable to reduce the framing overhead when transmitting command and/or control frames.
In one embodiment, the disclosure provides a method of communicating information in a communication system. The information may include a plurality of frames. Each frame in the plurality of frames may include a header and a body. The plurality of frames may be configured to be transmitted by a transceiver, or transmitter. The method comprises identifying at least two frames of different types configured to be transmitted by a transceiver, or transmitter. The method further comprises determining the capability of a first aggregated frame, including at least a portion of each of the at least two frames, to be transmitted by the transceiver within a first time duration, and formatting the first aggregated frame for transmission by the transceiver, if it is determined that the first aggregated frame is suitable for transmission within the first time duration.
In another embodiment the method further comprises placing an aggregation header with the aggregated frame. In another embodiment the method further comprises placing an altered header with each of the at least a portion of the at least two frames of different types. In another embodiment the altered header is a shortened header. In yet another embodiment the shortened header has fewer bits than the original header. In yet another embodiment, the plurality of frames represents voice, video, and/or data representing a physical object or substance. In another embodiment, the plurality of frames may also include command and/or control frames in addition to data frames.
In another embodiment, if the first aggregated frame is not suitable for transmission within the first time duration the method further comprises defining a second time duration that is longer than the first time duration, wherein the aggregated frame is suitable for transmission within the second time duration, and formatting the first aggregated frame for transmission by the transceiver within the second time duration.
In another embodiment each frame of the plurality of frames is originally configured to for transmission in separate time durations. In another embodiment the altered header includes at least one of frame control information, sequence control information and security information.
In yet another embodiment, a first frame of the at least two frames of different types comprises one of a data frame, a command frame, or a control frame, and a second frame of the at least two frames of different types comprises a different one of a data frame, a command frame, or a control frame. In another embodiment the different frames may be configured in any order.
In another embodiment determining the capability of the first aggregated frame to be transmitted within the first time duration includes determining the length of a header of the first aggregated frame, determining the length of a body of the first aggregated frame, and correlating the length of the header and the length of the body with the size of the first time duration.
In yet another embodiment the method comprises determining the capability of at least two frames of different types to be transmitted by a transceiver within a first time duration. If the at least two frames of different types are suitable for transmission within the first time duration, the at least two frames of different types are formatted for transmission by the transceiver within the first time duration.
In another embodiment if the at least two frames of different types are not suitable for transmission within a first time duration the method further comprises determining the capability of the at least two frames of different types to be transmitted within a second time duration that is longer than the first time duration. If the at least two frames of different types are suitable for transmission within the second time duration, the method further comprises formatting the at least two frames of different types for transmission by the transceiver within the second time duration.
The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. The techniques described herein may be used for various wireless communication networks such as Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA) networks, etc. The terms “networks” and “systems” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate (LCR). CDMA2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDMA, etc. UTRA, E-UTRA, and GSM are part of Universal Mobile Telecommunication System (UMTS). Long Term Evolution (LTE) is an upcoming release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). CDMA2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). These various radio technologies and standards are known in the art.
Single carrier frequency division multiple access (SC-FDMA) utilizes single carrier modulation and frequency domain equalization techniques. While SC-FDMA has similar performance and complexity as OFDMA systems, it also has a lower peak-to-average power ratio (PAPR) because of its inherent single-carrier structure. SC-FDMA has drawn great attention, especially in the uplink communications area where lower PAPR greatly benefits the mobile terminal in terms of transmit power efficiency. In addition, SC-FDMA is commonly implemented for the uplink multiple access scheme in 3GPP Long Term Evolution (LTE), or Evolved UTRA.
In some aspects the teachings herein may be employed in a network that includes macro scale coverage (e.g., large area cellular networks such as 3rd Generation (3G) networks, typically referred to as a macro cell network) and smaller scale coverage (e.g., residence-based or building-based network environment). As a wireless communication device moves through such a network, the wireless communication device may be served in certain locations by access nodes that provide macro coverage, while the wireless communication device may be served at other locations by access nodes that provide smaller scale coverage. In some aspects, the smaller coverage nodes may be used to provide incremental capacity growth, in-building coverage, and different services (e.g., for a more robust user experience). In the discussion herein, a node that provides coverage over a relatively large geographic area may be referred to as a macro node.
Frame aggregation (e.g., combining separate frames into an aggregate frame) at the Medium Access Control (“MAC”) layer may be used to amortize (e.g., reduce or mitigate) the framing overhead and increase the MAC efficiency. Certain communication standards may provide a method of data frame aggregation where multiple MAC Service Data Units (“MSDUs”) are packed in an aggregate data frame. Another method for reducing the framing overhead and increasing MAC efficiency comprises packing multiple data MAC Protocol Data Units (“MPDUs”) into an aggregated MPDU. It will be appreciated that the various embodiments and examples described herein are applicable to numerous communication systems or networks. Frame aggregation is to be interpreted broadly and includes, but is not limited to, placing frames adjacent to each other, interleaving, combining, shortening or modifying frames in any way for transmission.
In general, the methods presented herein for aggregating multiple MSDUs or MPDUs are applicable when the frames are to be transmitted between the same transmitter (e.g. source) and receiver (e.g. destination) address pairs. However, instead of using a transmitter or receiver, a transceiver at both the source and the receiver may be used. Thus, below whenever a transmitter or receiver is mentioned it is envisioned that a transceiver may be used interchangeably. The second method described above may have advantages over the first method, as each MPDU may be individually acknowledged and retransmitted. Errors in the MPDU may be isolated if each successive MPDU starts on a fresh interleaver boundary with a fresh convolutional decoder state. For channels with high bit-error-rate, packet error rate in the first method may increase with the length of the Physical Layer Service Data Unit (“PSDU”) where there is only one Frame Check Sequence (“FCS”) per PSDU. In one example, data, command, and control frames may originate from a single application, e.g., that is operating on or with the transmitter, or transceiver. In another example, the data, command, and control frames may originate from multiple applications.
In certain communications systems, the above-mentioned methods for aggregation apply to data frames only. In these types of communication systems, the above-referenced methods may not address the amortization of the high framing overhead for control or command frames, which are often shorter than data frames. Framing overhead may comprise any combination of the preamble, a Physical Layer Convergence Protocol (“PLCP”) header and inter-frame spacing In other communication systems (e.g., communication systems using 802.11n), different types of frames may be aggregated, but full MAC headers are required.
For communication systems using the WiMedia MAC (e.g., a MAC layer defined by WiMedia), one of the access mechanisms may be the Distributed Reservation Protocol (“DRP”). The DRP may allow a transmitter, or transceiver, to reserve one or more Medium Access Slots (“MASs”) to transmit frames. For example, in some communication systems, one MAS is 256 μs. In these communication systems, separate reservation periods may be used for sending command and/or control frames. In other communication systems, a single reservation may be used to transmit both data and command/control frames. In those communication systems where at least one MAS (e.g., 256 μs) is reserved for exchanging command and/or control frames, at least a portion of the slot time remains unused because command and/or control frames are generally shorter in duration than one MAS. An access mechanism known as Prioritized Contention Access (“PCA”) may reduce some of the wastage due to unused slot time. Thus, the use of separate MASs for command and/or control frames may result in a significant wastage of MAC capacity due to high framing overhead and the unused MAS time.
The functions described herein may be implemented in hardware, software, firmware, or any combination thereof. Implemented in software, the functions may be stored or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media include both computer storage media and communication media, including any medium facilitating transfer of a computer program from one place to another. Storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media include RAM, ROM, EEPROM, CD-ROM and other optical disk storage, magnetic disk storage and other magnetic storage devices, and any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general purpose or special-purpose computer, or a general-purpose or special-purpose processor, such as an application specific integrated circuit (“ASIC”). Also, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (“DSL”), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (“CD”), laser disc, optical disc, digital versatile disc (“DVD”), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.
In an embodiment, a combination of at least one control and/or command frame may be aggregated with a data frame. In another embodiment, one or more control frames may be aggregated with one or more command frames. For example, when the same transmitter, or transceiver, and receiver, or second transceiver, address pair exchange control, command and data frames, the pair can take advantage of aggregating MPDUs across different frame types. In another embodiment, the frame type field encodings in the frame control of the MAC header within the PLCP header may be modified in order to aggregate MPDUs across different frame types.
In addition, other aspects of the frames may be analyzed in order to determine if the frames should be aggregated. In one embodiment, if the frames require a high quality of service (QoS) with regards to latency i.e. are time-sensitive, the transmitter, or transceiver, will not aggregate the frames as it needs to flush out the frames as quickly as possible. In another embodiment, if an acknowledgement (“ACK”) is required after sending the aggregated frame and there is insufficient time to accommodate the ACK within the reservation duration, the transmitter, or transceiver, may not send the aggregated frame. In yet another embodiment, if the network is lightly loaded then the transmitter, or transceiver, may not aggregate the frames as the wasted MASs do not have any adverse impact.
Each of the wireless communication devices may communicate with the macro node 102 on a forward link (“FL”) and/or a reverse link (“RL”) at any given moment. A FL is a communication link from a macro node to a wireless communication device. A RL is a communication link from a wireless communication device to a macro node. The macro node 102 may be interconnected to macro nodes in other cells (not shown in this FIG.), for example, by appropriate wired or wireless interfaces. Accordingly, the macro node 102 may communicate with wireless communication devices in other cells (not shown in this figure).
With continuing reference to
A wireless communication device (e.g., 106) may be any wireless communication device (e.g., a mobile phone, router, personal computer, server, etc.) used by a user to send and receive voice or data over a communications network. A wireless communication device may be referred to as an access terminal (“AT”), and may also be referred to herein as a user equipment (“UE”), as a mobile station (“MS”), or as a terminal device. As shown, wireless communication devices 106 and 108 comprise mobile phones. However, the wireless communication devices may comprise any suitable communication device.
It may be desirable for a wireless communication device (e.g., 106) to transmit information to and receive information from another wireless communication device, such as wireless communication device 108 or a wireless communication device in another cell (not shown in this figure). The wireless communication device 106 may accomplish this by first communicating with the macro node 102 via a wireless link. For example, the wireless communication device 106 may generate and transmit a message to the macro node 102. The macro node 102 may then generate and transmit a message to another wireless communication device, such as wireless communication device 108. The messages may comprise information related to various types of communication (e.g., voice, data, multimedia services, etc.) and may include one or more aggregated frames, as discussed in detail below with reference to
With continuing reference to
The wireless communications network 200 may comprise a wireless local area network (WLAN) covering a physical area, like a home, office, or a group of buildings. A WLAN may use standards such as the 802.11 standard (e.g., 802.11g), and/or other standards for wireless communications. A WLAN may use a peer-to-peer communication in which the wireless communication devices directly communicate with each other. The wireless communications network 200 may also comprise a wireless personal area network (WPAN), spanning, for example, an area of a few meters. A WPAN may use standards such as infrared, Bluetooth, a WiMedia based UWB standard (e.g., ECMA-368), and ZigBee standards, and/or other standards for wireless communications. A WPAN may use a peer-to-peer communication in which the wireless communication devices directly communicate with each other. The wireless communications network 200 may connect to another network, such as the wireless communications network 100 or the Internet, through a device such as the wireless communications device 106.
The messages sent across the wireless communications network 200 may comprise information related to various types of communication (e.g., voice, data, multimedia services, etc.) and may include aggregated frames, as discussed in detail below with reference to
Although the following embodiments may refer to
The ECMA-368 standard specifies a physical layer (PHY) and a medium access control (MAC) sublayer for ultra-wideband (UWB) communication systems. For example, the ECMA-368 standard may be used in a high-speed, short-range wireless network. The ECMA-368 standard may use all or part of the frequency spectrum between 3100-10,600 MHz and may support data rates of up to 480 Mb/s, or even higher. The ECMA-368 standard divides the spectrum into 14 bands, each with a bandwidth of 528 MHz. The ECMA-368 standard may use a multi-band orthogonal frequency division modulation (MB-OFDM) scheme to transmit information. Frequency-domain spreading, time-domain spreading, and forward error correction (FEC) coding are provided for optimum performance under a variety of channel conditions.
The MAC sublayer of the ECMA-368 standard may allow a group of devices to continue communicating while merging or splitting from other groups of devices. The functionality of this MAC may be distributed among multiple devices. These functions include distributed coordination to avoid interference between different groups of devices by appropriate use of channels and distributed medium reservations to ensure Quality of Service. The MAC sublayer of the ECMA-368 may provide prioritized schemes for isochronous and asynchronous data transfer. Carrier Sense Multiple Access (CSMA) and Time Division Multiple Access (TDMA) are two different access mechanisms supported in ECMA-368. While they are not combined, both CSMA and TDMA can be supported. The MAC sublayer of the ECMA-368 standard may ensure equitable sharing of the bandwidth.
The processor 200 may process the outbound wireless message, and pass the outbound wireless message to the wireless network interface 208 for transmission. Additionally, the processor 200 may identify frames to be aggregated and may aggregate them, as will be discussed in detail below with reference to
The processor 200 may also be coupled to a message formatter 202. The message formatter 202 may generate or format the outbound wireless message to be transmitted by the wireless network interface 208. The wireless outbound message may be passed by the message formatter 202 to the processor 200 for transmission by the wireless network interface 208 to a macro node (e.g., 102). The message formatter 202 may be coupled directly to the memory 204 in order to store or retrieve information for use in message formatting. The message formatter 202 may organize aggregated frames from existing frames and/or insert modified headers with each frame that is part of the aggregated frame, as described in detail below with reference to
The wireless network interface 208 may comprise an antenna 208a and a transceiver 208b. The wireless network interface 208 may also comprise a convolutional decoder. The transceiver 208b may be configured to modulate/demodulate the outbound/inbound wireless messages going to or coming from the macro node 102. The antenna 208a may transmit/receive the outbound/inbound wireless messages. The antenna 208a may be configured to communicate with the macro node 102 over one or more channels. The outbound/inbound wireless message may comprise voice and/or data-only information (collectively referred to herein as “data”). The wireless network interface 208 may demodulate the data received. The wireless network interface 208 may modulate data to be sent from the wireless communication device 106 via the wireless network interface 208. The processor 200 may provide data to be transmitted.
The memory 204 may comprise a processor cache, including a multi-level hierarchical cache in which different levels have different capacities and access speeds. The memory 204 may also comprise random access memory (“RAM”), other volatile storage devices, or non-volatile storage devices. The storage devices comprising the memory 204 may include hard drives, optical discs, such as CDs or DVDs, flash memory, floppy discs, magnetic tape, and Zip drives.
Although described separately, it is to be appreciated that the functional blocks described with respect to the wireless communication device 106 need not be separate structural elements. For example, the processor 200 and the memory 204 may be embodied in a single chip. The processor 200 may additionally, or in the alternative, contain memory, such as processor registers. Similarly, one or more of the functional blocks or portions of the functionality of various blocks may be embodied in a single chip. Alternatively, the functionality of a particular block may be implemented on two or more chips.
One or more of the functional blocks and/or one or more combinations of the functional blocks described with respect to the wireless communication device 106, such as processor 200, message interpreter 206, and message formatter 202 may be embodied as a general purpose processor, a digital signal processor (“DSP”), an application specific integrated circuit (“ASIC”), a field programmable gate array (“FPGA”) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any suitable combination thereof designed to perform the functions described herein. One or more of the functional blocks and/or one or more combinations of the functional blocks described with respect to the wireless communication device 106 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP communication, or any other such configuration.
The processor 300 may also be configured to control other components of the macro node 102. The processor 300 may be further coupled to a wired network interface 308. The wired network interface 308 may be configured to receive an inbound wired message from and to transmit an outbound wired message to other destinations (e.g., other macro nodes). The wired network interface 308 may receive an inbound wired message and pass the inbound wired message to the processor 300 for processing. The processor 300 may process an outbound wired message and pass the outbound wired message to the wired network interface 308 for transmission.
The processor 300 may further be coupled, via one or more buses, to a memory 304. The processor 300 may read information from or write information to the memory 304. The memory 304 may be configured to store information for use in processing the inbound or outbound, wired or wireless message. The memory 304 may comprise a processor cache, including a multi-level hierarchical cache in which different levels have different capacities and access speeds. The memory 304 may also comprise random access memory (“RAM”), other volatile storage devices, or non-volatile storage devices. The storage may include hard drives, optical discs, such as compact discs CDs or DVDs, flash memory, floppy discs, magnetic tape, and Zip drives. The memory 304 may also store aggregated frames, as will be discussed in further detail below with reference to
The processor 300 may also be coupled to a message interpreter 306. The processor may pass the inbound wired and wireless message to the message interpreter 306 for processing. The message interpreter 306 may interpret aggregated frames.
The message interpreter 306 may also be configured to extract information from the inbound wireless message received at the wireless network interface 310. For example, the inbound wireless message received from the wireless communication device may comprise aggregated frames. The message interpreter 306 may extract the individual frames comprising identifying information from the aggregated frames. The message interpreter 306 may pass this identifying information to the processor 300 for additional processing. In another example, the message interpreter 306 may be configured to process the inbound wireless message and to provide the processor 300 with information for responding to the inbound wireless message. The message interpreter 306 may also be coupled directly to the memory 304 in order to store or retrieve information for use in message interpretation.
The processor 300 may also be coupled to a message formatter 302. The message formatter 302 may be configured to generate the outbound wired or wireless message. The message formatter 302 may be further configured to pass the generated outbound wired or wireless message to the processor 300. The message formatter 302 may organize aggregated frames from existing frames and/or insert modified headers with each frame that is part of the aggregated frame, as described in detail below with reference to
The processor 300 may pass the outbound wired or wireless message to the wired network interface 308 or the wireless network interface 310 for transmission. Additionally, the processor 300 may identify frames to be aggregated and may aggregate them, as will be discussed in detail below with reference to
The wired network interface 308 may transmit outbound wired messages to another macro node. The message formatter 302 may also be coupled directly to the memory 304 in order to store or retrieve information for use in message formatting.
The wireless network interface 310 may comprise an antenna 310a and a transceiver 310b. The transceiver 310b may be configured to modulate/demodulate the outbound/inbound wireless messages going to or coming from a wireless communication device. The antenna 310a may transmit/receive the inbound/outbound wireless messages. The antenna 310a may be configured to send and/or receive the outbound/inbound wireless messages from the macro node 102 over one or more channels. The outbound/inbound wireless messages may comprise voice and/or data-only information (collectively referred to herein as “data”) and may include one or more aggregated frames.
The wired network interface 308 may comprise a modem. The modem may be configured to modulate/demodulate the outbound/inbound wired message going to or coming from another destination/source, such as another macro node. The wired network interface 308 may demodulate the data received according to one or more wired standards using methods known in the art. The demodulated data may be transmitted to the processor 300. The wired network interface 308 may modulate data to be sent from the macro node 102 via the wired network interface 308 according to one or more wired standards using methods known in the art. In addition, the wired network interface 308 may also comprise a convolutional decoder.
Although described separately, it is to be appreciated that functional blocks described with respect to the macro node 102 need not be separate structural elements. For example, the processor 300 and the memory 304 may be embodied in a single chip. The processor 300 may additionally, or in the alternative, contain memory, such as processor registers. Similarly, one or more of the functional blocks or portions of the functionality of various blocks may be embodied in a single chip. Alternatively, the functionality of a particular block may be implemented on two or more chips.
One or more of the functional blocks and/or one or more combinations of the functional blocks described with respect to the macro node 102, such as processor 300, message interpreter 306, and message formatter 302, may be embodied as a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any suitable combination thereof designed to perform the functions described herein. One or more of the functional blocks and/or one or more combinations of the functional blocks described with respect to the macro node 102 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP communication, or any other such configuration.
The functionality of the modules of
As illustrated in
With continuing reference to
The PLCP header 404 may convey information to a wireless network interface (e.g., 208 or 308) for use in decoding the PSDU 406. As illustrated in
A WiMedia MAC frame includes a fixed-length MAC header and an optional variable length frame body.
In an embodiment, the aggregation of frames of different frame types (e.g., data, control, and/or command frames) exchanged between the same transmitter-receiver pair may amortize the overhead associated with transmitting the data, control and/or command frames. In an embodiment, the overhead associated with the additional preamble, PLCP header, Short Inter-Frame Space (“SIPS”) duration etc., for the command/control frame may be reduced or eliminated when the command/control is aggregated (e.g., piggybacked) with data frames. For example, instead of requiring a separate preamble, PLCP header, SIFS duration, etc., for each of the data and command/control frames, a data frame and the command/control frames may be transmitted in an aggregated frame. A detailed example of one embodiment of an aggregated frame is shown in
In the example shown in
As an example, if the estimated size of the aggregated frame would exceed the amount of time that was reserved, Transmitter 710 may choose not to aggregate the command frame 705 with the data frame 704. In another embodiment, if the estimated size of the aggregated frame would exceed the amount of time in Reservation A, Transmitter 710 may choose to increase (e.g. grow) Reservation A by one or more MASs. Having grown Reservation A to the appropriate size, Transmitter 710 may then construct the aggregated frame. If there is unused space in the increased reservation, additional frames, such as more data and command/control frames, may be added to the aggregated frame to fill up the unused space in the increased reservation. Alternatively, additional data, control or command frames can be sent as separate frames to make use of the unused reservation time, and the process may be repeated.
According to the example shown in
In another embodiment, there may be any combination of data, command, or control frames in the aggregated frame. For example, an aggregated frame may contain two data frames, two command frames, and two control frames. In another example, the aggregated frame may contain one data frame and two control frames, or one control frame and one command frame. Embodiments of the present invention thus provide for combinations of any number of data and any number of command and/or control frames to be combined in any order in an aggregated frame. This embodiment may also allow one of each of data, control and command frames to be combined in an aggregated frame.
In an embodiment, the aggregation of different types of frames may be done opportunistically. For example, an aggregated frame may be created only if there is space within a reservation. In another embodiment, an aggregated frame may be created only if the reservation can be increased by a certain amount and can accommodate the aggregated frame. In another embodiment the transceiver, or transmitter, may make a determination whether or not the different types of frames should be aggregated and then perform the aggregation if it is determined that the frames should be aggregated. A variety of factors may be used in this determination including, but not limited to, reservation size, data frame size, command frame size, control frame size, quality of service (QoS) requirements, which includes latency considerations, amount of network traffic, ACK requirements. In addition, if there is unused space in the increased reservation, additional frames may be added to the aggregated frame. Alternatively, additional data, control or command frames can be sent as separate frames to make use of the unused reservation time.
Table 1 illustrates exemplary identification values for the frame type field 608, as shown in
Embodiments provide for a separate frame control field for each of the data frame, control or command frame in the enhanced aggregated frame type. Also, there may be a need to have separate sequence control Information for each frame in the enhanced aggregated frame. In addition, there may be a need for security header information for each frame in the enhanced aggregated frame. In general, there may be no need to duplicate the Destination Address, Source Address and Access Information as they may remain the same for all the frames across types in the enhanced aggregated frame.
In an embodiment the Preamble 802 and PLCP header 803 are predefined in the WiMedia specification. The destination address, source address and access information in the MAC header of PLCP header may be common for all the aggregated frames. The sequence control fields of MAC header for an enhanced aggregated frame (e.g., in which the frame type is 5) may be set to the default reserved value (e.g., 0). In another embodiment, the sequence control fields may be the same as that in the first short MAC header of the first MPDU in the enhanced aggregated frame. Also in an enhanced aggregated frame, all fields in the frame control of the MAC header of PLCP header (except for Frame Type and Protocol Version) are reserved, e.g., are all set to zero.
The frame count field 902 may comprise one or more octets of information regarding the number of frames found within the aggregated frame. The length of MPDU fields (903, 904, 905) may comprise multiple octets of information regarding the length or size of each individual frame i.e. payload and the short MAC header, or just the payload. In another embodiment, the length fields may be included as part of the short MAC headers of the MPDU as shown in
With references to
The aggregation header of this embodiment will contain a frame count field, two length of MPDU fields for the two payloads, an FCS field, a tail bits field and a pad bits field. In this embodiment the frame count will be two because there is one data frame and one command frame. In this embodiment the length of the data frame payload 704 will be inserted into the length of MPDU 1 field 903 and the length of the command frame payload 705 will be inserted into the length of MPDU 2 field 904. The FCS, tail bits and pad bits fields may also be filled as needed.
In this embodiment, the short MAC header 1 field 805 will contain information specific to the data frame 704, and the short MAC header N field 809 will contain information specific to the command frame 705. In this embodiment, each short MAC header may contain information regarding the frame control, sequence control or other information relating to its respective payload.
In this embodiment, the payload 1 field 806 will contain the information found in the data frame payload 704b. The payload N field 810 will contain the information found in the command frame payload 705b. In addition each payload may have FCS field and a Tail bits field for resetting the decoder and error detection, and a pad bits field to align the data stream on the boundary of the symbol interleaver. In other embodiments there may be a pad bits field for each individual frame in the aggregated frame for alignment within the aggregated frame.
At block 1103, the length of the header of the aggregated frame is determined. At block 1104, the length of the body of the aggregated frame is determined. These determinations may be accomplished, for example, by a processor or similar device as discussed above.
At decision block 1105, the suitability of the aggregated frame to be transmitted within a first time duration, or reservation period, is determined. The aggregated frame is suitable for transmission if its characteristics, including, for example, any or all of size, length, and formatting characteristics, are deemed appropriate for transmission. It will be appreciated that other characteristics of an aggregated frame, as well as a variety of techniques, may be used for determining its suitability for transmission. In an embodiment, for example, it is determined whether there is sufficient time within the time duration, or reservation period, to transmit the aggregated frame within the reservation period. In another embodiment the length of the header of the aggregated frame and the length of the body of the aggregated frame may be correlated with the size of the reservation period. Here, the size of the reservation period is also understood to mean the length, or amount of time, or number of MASs, of the reservation period. A processor, or similar device, (e.g., 200, 300) may perform this determination. If the result of the determination is no, the method moves to block 1106 and produces instructions not to aggregate the frames. Additional instructions may be generated to transmit the frames independently, in separate reservation periods.
If the determination at block 1105 is YES, then the aggregated frame is formatted at block 1107 for transmission by the transceiver, or transmitter. The aggregated frame may thus be formatted, for example, at the transmitting device, or by the message formatter, by placing an aggregated header with the body of the aggregated frame and placing a shortened MAC header with each portion of the at least two frames of different types, or by preparing the already assembled aggregated frame for transmission. The aggregated frame may then be transmitted (not shown) by a transmitter, or transceiver, after block 1108, for example.
In addition, similar steps to aggregate additional frames to the aggregated frame may be performed within method 1100. For example, a third frame that is configured to be transmitted by the transceiver may be identified. The capability of a second aggregated frame to be transmitted by the transceiver within the first time duration may also be determined. The second aggregated frame would comprise at least a portion of the first two frames that were part of the first aggregated frame, and at least a portion of the third frame. The second aggregated frame for transmission by the transceiver would be formatted if it is determined that the second aggregated frame is suitable for transmission within the first reservation period. The formatting of the second aggregated frame could be accomplished in a similar matter to what is described previously with respect to the first aggregated frame. The second aggregated frame may then be transmitted within the first reservation period.
Additional frames could be aggregated to the three frames until it is determined that the aggregated frame is not suitable for transmission within the first reservation period, or an extended reservation period, as described above. The aggregated frame, may then be formatted for transmission, as described above, with as many portions of frames as it is suitable for transmission within the reservation period, or extended reservation period. The formatted aggregated frame may then be transmitted.
Additional decisions and functions may be performed alone or in combination with those described in
In one embodiment, the decision block 1301 may be inserted between blocks 1101 and 1102 of
In one embodiment, the decision block 1401 may be inserted between blocks 1101 and 1102 of
In one embodiment, the decision blocks 1501 and 1502 may be inserted between blocks 1105 and 1107 of
In one embodiment, the decision block 1601 may be inserted between blocks 1105 and 1107 of
The above-described methods may be realized in a program format to be stored on a computer readable recording medium that includes any kind of recording device for storing computer readable data, for example, a CD-ROM, a DVD, a magnetic tape, memory card, and a disk, and may also be realized in a carrier wave format (e.g., Internet transmission or Bluetooth transmission).
While specific blocks, sections, devices, functions and modules may have been set forth above, it will be appreciated that there are many ways to partition the system, and that there are many parts, components, modules or functions that may be substituted for those listed above. In addition, the blocks described in the above-referenced
While the above detailed description has shown, described, and pointed out novel features of the invention as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made by those skilled in the art without departing from the spirit of the invention. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope
The present application for patent claims priority to U.S. Provisional Application No. 61/164,317 entitled “METHOD AND SYSTEM FOR REDUCING HEADER INFORMATION IN WIRELESS COMMUNICATION SYSTEMS” filed Mar. 27, 2009, and assigned to the assignee hereof and hereby expressly incorporated by reference herein.
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