The above and other features and advantages of the present invention will become apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:
Exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Aspects of the present invention and methods of accomplishing the same may be understood more readily by reference to the following detailed description of the exemplary embodiments and the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art, and the present invention will only be defined by the appended claims. Like reference numerals refer to like elements throughout the specification.
Exemplary embodiments of the present invention are described hereinafter with reference to flowchart illustrations of user interfaces, methods, and computer program products according to exemplary embodiments of the invention.
It will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart block or blocks.
These computer program instructions may also be stored in a computer usable or computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer usable or computer-readable memory produce an article of manufacture including instruction means that implement the function specified in the flowchart block or blocks. The computer program instructions may also be loaded into a computer or other programmable data processing apparatus to cause a series of operational steps to be performed in the computer or other programmable apparatus to produce a computer implemented process such that the instructions that execute in the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.
And each block of the flowchart illustrations may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order depending upon the functionality involved.
In addition to the MCTA 14, the CTAP 11 is formed of a plurality of channel time allocations (CTAs) 15. The CTA 15 is classified into a dynamic CTA and a pseudostatic CTA. The dynamic CTA may be differently situated in each superframe, and cannot be used in the superframe if it lost the beacon. The pseudostatic CTA, on the other hand, is invariably situated in each superframe, and the CTA period may be used in a fixed position even if the pseudostatic CTA lost the beacon. However, if more than “mMaxLostBeacons” are lost, the CTA period cannot be used.
As mentioned above, IEEE 802.15.3 MAC is formed based on time division multiple access (TDMA) that guarantees stable QoS, and is optimum particularly for multimedia A/V streaming in a home network. However, IEEE 802.15.3 MAC needs to be improved in order to transmit AV data in a high frequency band in tens of GHz.
In general, the MAC frame transmitted and received among network devices includes a data frame and a control frame.
The control frame, which refers to all other frames except for the data frame, assists in the transmission of the data frame. For example, the control frame includes an association-request frame that requests participation in the network established by a network coordinator, a data slot request frame that requests a data slot frame to transmit isochronous data, a probe request frame that request a network search, a coordinator handover request frame that hands over its responsibility, and a response frame that responds to the aforementioned frames. In addition, the control frame includes an acknowledgement frame (ACK) that acknowledges receipt of a frame.
There is no significant difference between the size of the data frame and that of the control frame in IEEE 802.15.3. The data frame can be up to 2048 bytes and a command frame can be up to tens or hundreds of bytes. However, the data frame is enlarged in order to transmit the uncompressed AV data in the tens of GHz frequency band, while the command frame does not. Accordingly, the use of the conventional IEEE 802.15.3 is ineffective.
In the CAP 13 and the MCTA 14 of the conventional IEEE 802.15.3, each control frame and asynchronous data frame competitively access the channel. In this case, as the asynchronous data frame with relatively low importance has more chances of acquiring the channel than the control frame, the control frame necessary for the transmission of uncompressed isochronous data has less chance of being transmitted. In addition, the control frame with respect to data slot allocation and the frame required for the device to participate in the network have relatively higher importance than other control frames, however, they are in contention in the same period, thereby not being able to stably acquire the channel. If the device fails to transmit and receive such important control data, it will also lose an opportunity to transmit a mass of the uncompressed AV data. Accordingly, network throughput may drastically decrease.
Therefore, a time period required to transmit the relatively important control frame should be arranged in the superframe, and is deemed to be a contention period because a plurality of devices included in the network are in contention.
If the first device 400a that is not initially engaged in a network wishes to participate in the network, it needs to transmit an association-request frame to the network coordinator 300 competing with the second and third devices 400b and 400c during the contention period of the superframe ({circle around (1)} in
The control type field 41 displays a corresponding control frame, i.e., an identifier that identifies the association-request frame 40 and the length frame 42 records a sum of the following fields 43, 44, and 45 in bytes.
The device address field 43 records a hardware address of the first device 400a (e.g. a MAC address up to 8 bytes) that transmits the association-request frame 40. In addition, the device information field 44 records a variety of device information of the first device 400a such as a function, a performance, and a capacity. The ATP 45 displays a maximum time where the network coordinator 300 and the first device 400a sustain the association without communicating with each other. There is no communication therebetween for the maximum period of time when the network coordinator 300 is unassociated from the first device 400a.
As a response to the association-request frame 40, the network coordinator 300 transmits an association-response frame 50 to the first device 400a.
The control type field 51 displays an identifier that identifies the association-response frame 50 and the length field 52 records the sum of the subsequent fields 53, 54, 55, and 56 in bytes, and the device address field 53 records a hardware address of a first device.
The device ID field 54 records an ID that identifies the device in a network, and thus, may be much smaller (e.g. 1 byte) than the hardware address (e.g. 8 bytes). Accordingly, the device ID can reduce overhead when communication is established among the devices.
The ATP field 55 records a final time out determined by the network coordinator 400a. The final time may be different if the network coordinator 400a cannot support the request time in the ATP field 45 of
The code field 56 displays a value for an approval or a rejection. For example, 0 denotes approval, and 1 through 8 denote reasons for rejections. The reasons include an excess of associable devices, a lack of allocatable time slots, and a poor channel condition.
Not until the first device 400a receives an approval for the association-request from the association-response frame 50, is it engaged in the network. The first device 400a should ask the network coordinator 300 for a data slot ({circle around (3)} in
A request for the data slot can be made via a data-slot-request frame 60 of
The request-block field 64 may be formed of a target-number field 64a that denotes the number of receivers, a target-ID-list field 64b that lists IDs of the receivers, a stream-request-ID field 64c that identifies the version of the data-slot-request frame 60, a stream-index field 64d that is required to identify the data, a minimum time unit (TU) field 64e that denotes a minimum size required for the data slot, and a desired TU field 64f that denotes a desired size of the data slot.
If the first device 400a transmits the data-slot-request frame 40 to the network coordinator 300 through contention with the second and third devices 400b and 400c during a contention period ({circle around (3)} in
A payload 20 of the data-slot-response frame 70 may be formed of a control-type field 71, a length field 72, a stream-request-ID field 73, a stream-index field 74, an available-TU-number field 75, and a code field 76.
Fields 71, 72, 73, and 74 record the same contents as the data-slot-request frame 60. In addition, the available-TU-number field 75 records the number of TU per data slot that is finally allocated by the network coordinator 300. Then the code field 76 displays a value for an approval for or a rejection of the data slot request.
The network coordinator 300 transmits the data-slot-response frame 70, and broadcasts a superframe including the data slots allocated to the first, second and third devices 400a, 400b, and 400c during the beacon period ({circle around (5)} of
If the first device 400a receives a data slot from the network coordinator 300 by the broadcasted superframe, the first device 400a can transmit uncompressed AV data to the second device ({circle around (6)} of
The contention period according to the exemplary embodiments of the present invention is different from the contention period according to the conventional IEEE 802.15.3. The contention period according to exemplary embodiments of the present invention separately arranges the period for the control frame with respect to highly important specific functions. That is, conventionally, the contention period is where a channel is acquired through contention among the frames regardless of a time-division method. However, the contention period according to an exemplary embodiment of the present invention is time-divided in accordance with a specific function.
Referring to
The request for the data slot and the response thereto must be made in order to reserve the data slot that transmits the uncompressed AV data, and thus, are separated from other control frames or the asynchronous data frame period.
Despite the separating period, the slot reservation may be made in the “CP” period 82 through contention with other control frames, in addition to the “BWP” period 83.
A “CFP” period 84 is a non-contention period, and is composed of a plurality of data slots, each of which is used to transmit uncompressed AV data.
Information on the “BWP” period 83 is in the form of an Information Element, and may be included in a beacon frame with other Information Elements, and may be transmitted to each device. The beacon frame is transmitted in a “B” period 81.
Referring to
All Information Elements included in a beacon frame has identification information such as an ID, which is recorded in the element-identification information 91. Therefore, a device that has received the beacon frame can recognize corresponding information as the Information Element having information on a “BWP” period 83 by the element identification information.
The length filed 92 records the sum of the fields 93, 94, 95, and 96 in bytes.
The “BWP Frequency” field 93 may record “Always” or “Intermittent”. If a value corresponding to “Always” is recorded, the “BWP” period 83 exists in all superframes but if a value corresponding to “Intermittent” is recorded, the “BWP” period 83 intermittently exists in the superframes. That is, the “BWP Frequency” field 93 is information indicating the frequency of the “BWP” period 83 in the superframe.
A value corresponding to 1 or more may exist in the “BWP FreqCount” field 94. For example, if the “BWP Frequency” field 93 is set to a value corresponding to “Always”, the “FreqCount” field 94 is set to “1”.
Conversely,
A “BWP Location” field 95 denotes an initial location where a “BWP” period starts. For example, the initial location can be traced when offset information is recorded from the point at which a device has received a beacon frame. The offset information may be recorded in units of microseconds (μs). A “BWP Duration” field 96 denotes the length of a “BWP” period 83.
Conversely,
Referring to
In addition, information on the “CP” period is created in the form of an Information Element, and may be included in a beacon frame with other Information Elements, and be transmitted to each device. Here, the created Information Element may have the same configuration as the Information Element of
Conversely,
In addition, information on a “CP” period is in the form of an Information Element, and may be included in a beacon frame with other Information Elements, and transmitted to devices.
Information on the “BWP” period included in the beacon frame may be flexibly managed depending on the condition. For example, if a data slot request is not frequently made, it is ineffective to separately have the “BWP” period. Therefore, a network coordinator may manage the “BWP” period intermittently. If the “BWP” period does not exist in the superframe, the request for the data slot and a response thereto can be executed.
The network coordinator 300 may include a CPU 310, a memory 320, a MAC unit 340, a PHY unit 350, a superframe-generation module 341, a control frame-generation module 342, and an antenna 353.
The CPU 310 controls other components connected to a bus 330, and is in charge of a process in an upper layer of a MAC layer. That is, the CPU 310 processes a received MAC service data unit (MSDU) from the MAC unit or generates a transmitted MSDU and provides it to the MAC unit 340.
The memory 320 stores the processed received MSDU or the generated transmitted MSDU temporarily. The memory may be implemented in a volatile memory such as a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electronically erasable programmable read-only memory (EEPROM), and a flash memory, or a non-volatile memory such as a random-access memory (RAM), or a storage media such as a hard disk and an optical disk, or other forms well known in the related art.
The media access control (MAC) unit 340 appends a MAC header to the MSDU provided from the CPU 310, i.e., multimedia data-to-be-transmitted, and generates a MAC protocol data unit (MPDU). The MAC unit 340 then transmits the MPDU to the PHY unit 350, and erases the MAC header from the MPDU transmitted via the PHY unit 350.
As described above, the MPDU transmitted by the MAC unit 340 includes a superframe that is transmitted during a beacon period. The MPDU transmitted by the MAC unit 340 includes an association-request frame, a data-slot-request frame, and a variety of control frames.
The superframe-generation module 341 generates one of the superframes described above, and provides it to the MAC unit 340 and the control frame-generation module 342 generates the association-request frame, the data-slot-request frame, and other control frames and provide these to the MAC unit.
The PHY unit 350 appends a signal field or a preamble to the MPDU provided by the MAC unit 340, and generates a PPDU. The generated PPDU, i.e., the data frame, is converted into a signal, and transmitted through the antenna. The PHY unit 350 may be further divided into a baseband processor 351 that processes a baseband signal, and a radio frequency (RF) unit that generates a radio signal from the baseband signal, and transmits it via an antenna 353.
Particularly, the baseband processor 351 formats the frames and codes the channels and the RF unit 352 amplifies analog signals, converts digital signals into analog signals or vice versa, and modulates the signals.
A timer 441 checks the time when a contention or a non-contention period included in a superframe starts and ends. A control frame-generation unit 442 generates an association-request frame and a data-slot-request frame, and provides them to a MAC unit 440.
An uncompressed-AV-data-generation module 443 generates and stores uncompressed AV data. For example, the uncompressed-AV-data-generation module 443 records video data composed of RGB values.
The MAC unit 440 generates MPDU by appending a MAC header to the uncompressed AV data or the control frame, and transmits the MPDU via a PHY unit 450.
The term “module” described with reference to
As described above, according to exemplary embodiments of the present invention, AV data can be efficiently transmitted through mmWave (in tens of GHz).
The exemplary embodiments of the present invention have been explained with reference to the accompanying drawings, but it will be apparent to those skilled in the art that various modifications and changes may be made thereto without departing from the scope and spirit of the invention. Therefore, it should be understood that the above exemplary embodiments are not restrictive but illustrative in all aspects.
Number | Date | Country | Kind |
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10-2006-0050518 | Jun 2006 | KR | national |