64 results about "Inter frame space" patented technology

A method and apparatus enables advanced signal processing in a wireless local area network (WLAN). First and second WLAN transceivers are provided with advanced signal processing capabilities. A maximum interframe period between data and an acknowledgement is required by the WLAN for compatibility. A duration of the interframe period is shorter than a duration that is required to perform the advanced signal processing. The first WLAN transceiver transmits a header and data. A first data field in the header is specified that enables the advanced signal processing. A second data field is specified that defines a data time period and an extension time period. The first WLAN transceiver transmits data during the data time period and dummy data during the extension time period. The second WLAN transceiver receives the header and initiates receiver processing during the extension time period.

The invention discloses a carrier sense method and a system. According to the method, a transmitting terminal sends an idle channel to assess clear channel assessment (CCA) request frames on a main channel of a transmission channel which needs to be detected; the transmitting terminal sends request to send (RTS) frames on the transmission channel which needs to be detected after sending a point coordination function inter-frame space (PIFS) subsequent to transmission of the CCA request frame; and the transmitting terminal performs data transmission on the transmission channel transmitting clear to send (CTS) frames after receiving an indication that CTS frames are permitted to send. The invention also discloses the carrier sense system, which comprises a transmitting terminal and a receiving terminal. According to the method and the system, the power consumption of the receiving terminal is reduced and reliable CCA results of all transmission channels are provided.

The invention provides an extraction method of semantic information of video images, and relates to the technical field of video description and annotation. Firstly, frame sequences of a video are extracted according to a certain inter-frame space, a feature vector of each frame image is extracted according to a convolutional neural network, the feature vectors are regarded as input of a LSTM network encoder, output of each time step of the LSTM network encoder and output of the previous time step of a LSTM network decoder are regarded as input of an external storage EMM, and contents of a stored matrix in the external storage EMM are updated; the external storage EMM outputs two reading vectors which are regarded as input vectors of decoding and encoding of the subsequent time step respectively. Through two LSTM network dynamics, reading and writing of the external storage EMM are controlled, and storing of the feature vector of each frame image of the video at the encoding phase is achieved; at the decoding phase, through forecasting of feedback of words, the output of the subsequent time step of the external storage is adjusted, so that when an annotation of the video is generated, the feature vectors of a context are adjusted according to a generated word sequence.

Embodiments of the present invention provide a method, apparatus, and system of wireless transmission with frame alignment. For example, a method in accordance with demonstrative embodiments of the invention may include synchronizing between a transmitter using a first modulation scheme, which may have multiple frame formats, and a receiver using a second modulation scheme, by calculating a transmission time that aligns an inter frame space start time of the first and second modulation schemes. Other features are described and claimed.

The invention relates to a method for accessing an 802.11 wireless network channel under centralized control. On the premise of retaining a competitive mechanism, the method changes a random backoff channel accessing mode into a wireless controller (AP, access point)-based centralized control mode, thus optimizing the following problems in the channel accessing process: (1) the waiting time for random backoff of a station (STA) is not necessary and different inter-frame space (IFS) durations are uniformly replaced by a short inter-frame space (SIFS) duration, thus reducing time delay of frame transmission, improving the use ratio of a channel and greatly increasing the throughput of a system; (3) when multiple stations compete for channels simultaneously, the occurrence of collision is avoided, the accessing time delay of the stations is reduced, and the packet loss rates of the stations are reduced; and (4) stations do not use channel availability assessment (CAA), thus reducing energy consumption of the stations.

The invention discloses a distributed media access method used in a wireless local area network. According to the method, on the basis of a distributed coordination function (DCF)-based media access method specified in the conventional standard, the time length of DCF inter-frame space (DIFS) is set by randomizing: namely, a random time length deltaDIFS is added on the basis of the set time length of the DIFS specified in a protocol; moreover, in order not to add excessive channel overhead, the time length deltaDIFS is recommended to be set within a set time slot length, namely, delta DIFS=random (0, Slot_time); the time length of the DIFS is used for avoiding a phenomenon that different users synchronously enter a random backoff window wait state because of selecting contention windows (CWs) with the same time length, so that data collision probability and retransmission numbers among different users are reduced; channel utilization rate is improved; and system throughput is increased. Because only the time length of the DIFS is modified (namely the time length of the DIFS is subjected to randomization processing), the method is simple in operation and easy to develop, cannot increase system complexity, and does not need to update conventional sites; and new sites are compatible with old sites mutually, so that the application range of the method is enlarged, and the method has very good popularization and application prospect.

The invention discloses a method and a system for transmitting channel feedback information, and is applied to a very high throughput (VHT) wireless local area network system. The method and the system are used for solving the problem of bandwidth selection during the channel information feedback of a receiving party and the problem of interference caused by no clear channel assessment (CCA) detection of the receiving party under the condition of an overlapping basic service set. Before a transmitting party transmits a wireless frame for requesting for the channel feedback information, at least a specified inter-frame space is required to be reserved for the CCA detection of the receiving party within the specified inter-frame space, and the receiving party performs the CCA detection before the channel feedback information is transmitted, so that a clear bandwidth in line with a protocol requirement can be selected to transmit the channel feedback information. Therefore, the problem of the interference caused by the overlapping basic service set and the problem of channel feedback bandwidth selection can be solved.

The invention belongs to the technical field of security and protection monitoring and provides a video playing method and device. The video playing method comprises the steps of receiving video source data, dividing the video source data into video data and audio data, buffering the video data in a preset video buffering region and buffering the audio data in a preset audio buffering region and calculating inter-frame space of the received video source data; if the playing duration of the data buffered in the video buffering region and the playing duration of the data buffered in the audio buffering region respectively reach to a size set between the buffering regions, respectively decoding and playing a first frame of the video data and a first frame of the audio data; calculating a time interval of the current frame which shall be played based on the inter-frame space of the received video source data and the playing duration of the data buffered in the current buffering regions; and obtaining the decoding time of the next frame of the video data and the audio data based on the time interval of the current frame which shall be played. The video playing method and device can improve a standstill problem during the video playing process and can improve the video playing smoothness.

The invention discloses a vehicle tracking method and vehicle tracking system based on the video identification technology, wherein a fixed region is defined at the bottom of a video image so as to detect the appearance of vehicles. An inter-frame space number of system frame difference is determined according to vehicle length and vehicle speed. When the vehicle appears, the running speed stage of the vehicle is judged according to a frame difference value and a special threshold, if the vehicle frame difference value is more than the set threshold, the violation state of the vehicle is detected by a virtual loop method, if the vehicle frame difference value is not more than the set threshold, the violation state of the vehicle is detected by a background difference subtraction tracking method. The system relates to vehicle detection and tracking methods and systems for the same based on machine vision; and the method comprises the following steps of: capturing images, establishing and updating background, detecting vehicle appearance, judging the running state of the vehicles, and respectively selecting the virtual loop method or the tracking method to detect the red-light violation behaviors of vehicles according to the running state of the vehicles.

A communication apparatus to transmit a plurality of frames in a network, where each frame includes one or more symbols having a symbol length, includes a data processing unit. The data processing unit acquires an inter-frame space between two consecutive frames from the plurality of frames. The data processing unit further adjusts the inter-frame space between the two consecutive frames upon determination that the inter-frame space is not an integral multiple of the symbol length. The communication apparatus also includes a transmitter unit to transmit the adjusted consecutive frames.

A station (STA), an access point (AP) and method of adjusting for detection of an Overlapping Basic Service Set (OBSS) packet is disclosed. The STA may initiate a counter in response to determining that a BSS packet is to be transmitted. A packet may be detected on the channel and the counter suspended. If the packet is a BSS packet, the counter may be reset and restarted. If the packet is an OBSS packet, the counter may be decremented by a time to detect and determine that the packet is the OBSS packet and subsequently restarted prior to transmitting the BSS packet when the counter reaches 0. The counter may be further decremented by an Inter Frame Space period. If the counter after being decremented is 0, the BSS packet may be transmitted immediately, the counter may not be decremented or may be incremented by a backoff window.

The embodiment of the invention provides a data packet sending method and an access point, wherein the data packet sending method comprises the following steps of: at the beginning of a period, setting a local inter-frame spacing interval as a first numerical value by the access point, wherein the first numerical value is less than a preset second numerical value; setting a contention window as zero; calculating at the beginning of the period, during a duration time of a special flow, when the idle time of a channel reaches the preset inter-frame spacing interval, controlling the sending of a data packet of a special type; after the duration time of the special flow from the beginning of the period, setting the inter-frame spacing interval as a preset inter-frame access parameter, wherein the numerical value of the preset inter-frame access parameter is more than or equal to the second numerical value; and modifying the contention window as a preset window parameter value. By using the technical scheme provided by the embodiment of the invention, an AP (Access Point) can be successfully contended and accessed to the channel; and the data packet of the specific type can be sent in time.

A wireless communication device in a wireless system may generate a High Efficiency Physical Layer Convergence Procedure (PLCP) Protocol Data Unit (HE PPDU) frame including (i) an Orthogonal Frequency Division Multiplexing (OFDM) symbol including padding bits and (ii) an extension having a non-zero signal strength, and transmit the HE PPDU frame. A High Efficiency signal (HE-SIG) field of the transmitted HE PPDU frame may include an indication for a duration of the extension to avoid ambiguity of the extension. A communication device in a wireless system may receive an HE PPDU frame including (i) an OFDM symbol including padding bits, and (ii) an extension having a non-zero signal strength, and transmit an Acknowledgement frame a predetermined inter-frame space after an end of the HE PPDU frame. An HE-SIG field of the received HE PPDU may include an indication for duration of the extension to avoid ambiguity of the extension.

A method and a system for medium access control among devices in a communication system is provided. One implementation involves selecting a contention-based control period for access to a shared communication medium; dividing the contention-based control period into multiple time slots, wherein each slot has a duration that is a function of one or more of the duration of transmission of a request to send (RTS) frame, the duration of transmission of a clear to send (CTS) frame, and an inter frame space (IFS) duration therebetween; and transmitting an RTS frame in a selected slot for allocating a reservation period for accessing the medium for data transmission.

Embodiments of methods and systems for supporting coexistence of multiple technologies in a Power Line Communication (PLC) network are disclosed. A long coexistence preamble sequence may be transmitted by a device that has been forced to back off the PLC channel multiple times. The long coexistence sequence provides a way for the device to request channel access from devices on the channel using other technology. The device may transmit a data packet after transmitting the long coexistence preamble sequence. A network duty cycle time may also be defined as a maximum allowed duration for nodes of the same network to access the channel. When the network duty cycle time occurs, all nodes will back off the channel for a duty cycle extended inter frame space before transmitting again. The long coexistence preamble sequence and the network duty cycle time may be used together.

The invention relates to a video recognition method and device. The method includes acquiring a target video; dividing the target video according to a first preset inter-frame space so as to obtain a plurality of video segments; extracting first frame images from all the video segments according to a second preset inter-frame space; extracting first frame images containing human face information so as to obtain second human face frame images; based on a preset recognition model, identifying identities of human faces in the second human face frame images and determining human face marks contained in the second human face frame images; according to the corresponding relation between the human face marks and the second human face frame images and according to the corresponding relation between the second human face frame images and the video segments to which the second human face frame images belong, forming a three-party corresponding relation table of the human face marks, the second human face frame images and the video segments. Therefore, video segments containing actors that a user expects to see can be pushed to the user according to the determined corresponding relation between the video segments and the human face marks.

The invention, which relates to the technical field of digital image processing, discloses a fish body moving speed detection method for water quality monitoring. A camera collects a fishing body moving video; the video is read and is separated frame by frame; pretreatment is carried out on images; background modeling is carried out to obtain a final background image; an adaptive optimal segmentation threshold value is obtained by using a Otsu algorithm; difference processing is carried out on each video frame of image and the final background image to obtain a fish body moving target image; a fish body moving target mass center position is obtained by using a communication zone mass center method and a mass center is obtained; a ratio value of a practical distance and a pixel coordinate distance is determined and a moving distance of the fish body during a period is solved; moving time is determined based on a relation between a video frame rate and an inter-frame space; a fish body moving rate is solved based on the relation; a moving direction angle of the fish body at a current time is determined; and according to a current position of the fish body and a moving speed rule, a water environment changing situation is analyzed. According to the invention, the moving speed of the fish body can be obtained accurately in real time; the detection cost is lowered; and the detection precision of the algorithm is improved.

The invention discloses an accident detection method for recognizing a vehicle collision through a traffic monitoring video. The method includes the steps that 1, a stop behavior in an area target is determined; 2, the direction and amplitude of a surrounding historical light stream of the stop behavior are calculated according to an inter-frame space, and whether a light stream collision point exists around the stop behavior is judged; if yes, it is determined that the collision accident happens, the accident is reported, and judgment is finished; otherwise, the step 3 is executed; 3, the inter-frame space is changed, the direction and amplitude of the surrounding historical light stream of the stop behavior are recalculated, and whether a light stream collision point exists around the stop behavior is judged; if yes, it is determined that the collision accident happens, the accident is reported, and judgment is finished; otherwise, the step 3 is repeatedly executed till the inter-frame space exceeds 5, and it is determined that no collision accident happens currently if no light stream collision point is found around the stop behavior. The method is simple in principle and convenient to implement and has great practical value.

Methods and apparatuses for providing closed-loop power control during a short inter-frame space (SIFS) burst are described herein. A method includes receiving feedback associated with transmit power used to transmit a first data packet in a SIFS burst. The method also includes adjusting at least the transmit power, or a modulation and coding scheme (MCS), or a combination thereof, used to transmit a second data packet of the SIFS burst based at least in part on the received feedback.

The invention relates to a method for enabling multiple vehicles to broadcast a message simultaneously through multi-channel CSMA. The method comprises the steps that (1) N channels which do not overlap each other are set in advance; (2) each vehicle node keeps monitoring the N channels; (3) whether an idle channel list is empty or not is checked when the vehicle nodes prepare to broadcast and emit an emergent information frame; (4) waiting a time interval lasting for at least one inter-frame space is conducted and whether RSS is smaller than ST all the time or not is checked before the vehicle nodes actually broadcast and emit the emergent information frame; (5) whether the RSS is smaller than the ST all the time is checked at any moment in a random access rollback period; (6) one used channel is marked as 'a channel used last time'. Compared with the prior art, the method for enabling the multiple vehicles to broadcast the message simultaneously through the multi-channel CSMA has the advantages that the spectral efficiency is improved through the multi-channel CSMA protocol integrating FDMA and / or CDMA, so that the information transmission delay of the vehicle nodes in the vehicle environment with a large density can be obviously reduced.

Embodiments of methods and systems for supporting coexistence of multiple technologies in a Power Line Communication (PLC) network are disclosed. A long coexistence preamble sequence may be transmitted by a device that has been forced to back off the PLC channel multiple times. The long coexistence sequence provides a way for the device to request channel access from devices on the channel using other technology. The device may transmit a data packet after transmitting the long coexistence preamble sequence. A network duty cycle time may also be defined as a maximum allowed duration for nodes of the same network to access the channel. When the network duty cycle time occurs, all nodes will back off the channel for a duty cycle extended inter frame space before transmitting again. The long coexistence preamble sequence and the network duty cycle time may be used together.

The invention relates to an on-line target tracking method based on probabilistic principal component analysis and compressed sensing. A compressed sensing theory is combined with a PPCA (probabilistic principal component analysis) theory to obtain a quite simple target characteristic subspace representation model, and the target subspace representation model is updated on line by the aid of an incremental PCA (principal component analysis) algorithm to enable a tracking algorithm to achieve good real-time performance. Meanwhile, the PPCA theory is applied to computation of visual similarity of a candidate target and the target subspace representation model to obtain a DFFS (distance from face space) and a DIFS (distributed inter-frame space) not just reconstruction errors in PCA, so that visual similarity is computed more accurately, and further accuracy of the tracking algorithm is guaranteed.

The invention discloses a self-organized terahertz network-orientated auxiliary type directed communication method which comprises the following steps: a common node acquires own position information in a way of communicating with an anchor node all round; when needing to send data, a sending node avoids a distributed inter-frame spacing first, then starts to monitor an adopted low-frequency channel, and if the channel is occupied, avoids until the channel is empty; the sending node sends an extended request sending frame to a receiving node through a low-frequency all-round antenna, and the receiving node returns a clearing sending frame with the own position information and antenna information to the sending node; the two nodes carry out calculation to obtain a direction and a beam width of the antenna; the sending node sends a test frame to the receiving node through a directed terahertz antenna after waiting an antenna conversion time; after data sending is completed, the receiving node returns an ACK again; and if the sending node receives the ACK successfully, the whole sending process is completed. The invention further discloses network architecture for implementing the method.

A wireless transmission method, performed in a second layer of a wireless LAN apparatus, for transmitting data from a first layer of the wireless LAN apparatus to a third layer of the wireless LAN apparatus, comprising steps of: retrieving information related to unacknowledged frames from the first layer; aggregating the unacknowledged frames into a data unit if a processing time of the retrieving and aggregating step is less than a short inter frame space corresponding to a transmission opportunity; and transmitting the data unit to the third layer in the transmission opportunity.

Methods, systems, and devices are described for wireless communication at a wireless device. A wireless device (e.g., station or access point) may adapt short inter-frame space (SIFS) burst parameters to improve the performance of the overall network while providing enriched user experience. A wireless device may monitor traffic conditions on the network and dynamically adapt the SIFS burst parameters associated with one or more stations based at least in part on detected variations on the traffic channel. In other examples, the wireless device may allocate a common SIFS burst parameter to be used by a plurality of wireless devices in the basic service set (BSS).

The present invention discloses a panoramic stereo image synthesis method and apparatus, and a mobile terminal thereof. The panoramic stereo image synthesis method comprises: obtaining image information, wherein the image information is a group of multiple continuous frames of images; separating extracting two frames of images meeting preset inter-frame space from the multiple continuous frames of images, and separately performing stereo image synthesis on the two extracted frames of images, to obtain a group of multi-frame stereo images from different perspectives. According to the panoramic stereo image synthesis method and apparatus and the mobile terminal thereof, panoramic stereo image synthesis is implemented, and a demand of a user for watching a panoramic stereo image is met.

The invention relates to the wireless data transmission technology, in particular to an intelligent allocation method for a wireless flow. The method has the main technical schemes of: according to an adaptation speed and a data amount of a wireless client end, obtaining the occupied time of a wireless medium, by dividing the time of an access point into time pieces T, and by utilizing a mobile index smoothing method, estimating the occupied time of the medium of the wireless client end in the next time piece T; and flexibly applying a size of a competition window and an arbitration inter-frame space (AIFS) in the criterion of 802.11e to set different priority levels for various queues, and thus realizing the intelligent allocation of the wireless flow. The method has the beneficial effects that a wireless network can be enabled to reduce affects of a client end with a low speed and poor signal quality on the client end with the high adaptation speed and good signal quality in the situation of a high load, the experience of wireless Internet surfing of the client end with the high adaptation speed and good signal quality is promoted, and thus the throughput capacity of an overall wireless network is improved. The method is particularly suitable for the allocation method for the wireless data flow.

The invention provides a communication method and a communication device of a wireless local area network and an access point. The communication method of the wireless local area network comprises the steps of receiving an uplink data frame; generating an aggregated data frame which comprises a communication resource distribution message frame and a confirmation message frame used for feeding back a reception condition of the uplink data frame, wherein the communication resource distribution message frame is used for distributing a transmission resource that is adopted when the uplink data are transmitted to the station again; and sending the aggregated data frame. According to the technical scheme, the access point can aggregate the confirmation message frame which is fed back to the station and the communication resource distribution message frame which is used for distributing the transmission resource to the station again for transmission, so that time of SIFS (Short Inter-frame Space) is saved, the utilization rate of the frequency is increased, and the throughput of an area is improved indirectly.

A method for detecting proximity of two communicating devices is disclosed. Proximity may be determined by measuring deviation from standardized signal timing specifications. An embodiment uses inter-frame space parameters specified by the Bluetooth Low Energy protocol to do proximity detection, and presents a solution that may prevent or mitigate relay attacks. The method offers the advantage that the use of an existent frame timing protocol eliminates the need for specific hardware or firmware modifications.