57 results about "CA protocol" patented technology

Apparatus and accompanying methods for use therein for implementing an integrated, virtual office user environment, through an office server(s), through which a remotely stationed user can access typical office network-based applications, including e-mail, file sharing and hosted thin-client programs, through a remotely located network, e.g., WAN, connected web browser. Specifically, a front end, namely a service enablement platform (SEP), to one or more office servers on a LAN is connected to both the WAN and LAN and acts both as a bridge between the user and his(her) office applications and as a protocol translator to enable bi-directional, web-based, real-time communication to occur between the browser and each such application. During initial operation, the SEP, operating under a default profile, establishes, over an analog connection to the WAN, a management session with the site to obtain customer WAN access information, then tears down the analog connection and establishes a broadband WAN connection through which the SEP re-establishes its prior session and obtains a client certificate and its customized profile. The SEP then re-initializes itself to that particular profile.

The invention provides an outdoor wireless communication system based on a LoRa ad-hoc network, which is used for solving technical problems of poor mobile network signals in severe environment, short transmission distance and absence of an interactive interface for information sharing of the existing outdoor wireless communication system. The outdoor wireless communication system based on the LoRa ad-hoc network comprises a central processing unit, a positioning module, a Bluetooth module, a peripheral interface, a power supply module, a LoRa communication module and a mobile phone APP terminal; the central processing unit is respectively connected with the positioning module, the Bluetooth module, the peripheral interface, the power supply module and the LoRa communication module; the LoRa communication module constructs a wireless Mesh network with the LoRa communication modules of other systems, and performs reliable data communication through a CSMA/CA protocol and an AODV routing algorithm; and the mobile phone APP terminal and the Bluetooth module perform data exchange through the Bluetooth. The outdoor wireless communication system based on the LoRa ad-hoc network performs communication without the mobile network, has long transmission distance, has the interactive interface for information sharing, and can be applied to the fields, such as the Internet of Vehicles and the Internet of Things.

Transmission over a communication channel using carrier sense multiple access collision avoidance (CSMA/CA) may be performed by determining for each frame if the communication channel is busy after a backoff time proportional to a randomly generated number within a contention window (CW). When the channel is not busy, a frame of data may be transmitted. When the channel is busy, the device may periodically determine if the communication channel is busy after subsequent backoff times. The value of CW is adjusted for each subsequent backoff time using a fairness protocol, in which the value of CW is increased until the value of CW reaches a maximum CW value; and then the value of CW is held until a fairness number of backoff repetitions reaches a fairness threshold; then the value of CW is reduced incrementally until the value of CW reaches a minimum CW value.

The invention discloses a visible light full duplex continuous transmission random access method based on a channel reservation mechanism. Different from the CSMA/CA protocol in the existing IEEE802.15.7 standard, after a user executes idle channel estimation and detects that the channel is in an idle state, the user does not directly send a data frame, but firstly sends a RTS frame to reserve the channel, and sends the data frame after successfully reserving the channel. A full duplex visual light access point needs to broadcast busy tone to eliminate the hidden nodes when receiving the RTS frame or the data frame. Moreover, the user can directly execute CCA without executing random evasion again after successfully transmitting the data frame, therefore the conflict of the data frame is prevented, the time slot resources consumed by the random evasion mechanism are reduced, and the throughput and delay performance are improved. By adoption of the visible light full duplex continuous transmission random access method, the visible light hidden node problem is effectively solved, and meanwhile, the throughput and the delay performance of the visible light CSMA/CA protocol is optimized at the same time.

The invention provides an inter-satellite networking communication method for a small satellite cluster. The method comprises the following steps that: (1) a center node and an ordinary node are set; (2) a physical channel is divided into a networking channel and a data channel, and each satellite node shares the physical channel through a CSMA/CA mode of an IEEE802.11 protocol; (3) the center node sends a networking beacon frame by using the networking channel, the ordinary node carries out monitoring, and after the reception, a request association frame is sent to the center node if the access to a network is decided; (4) after the center node receives the request association frame, whether the access of an ordinary node into the network is allowed or not is judged according to the identity verification and network capacity information, the corresponding association application feedback information is sent to the ordinary node, after the networking is completed, each ordinary node employs a roll polling mode to carry out measurement and control data communication under the control of the center node, and after the measurement and control data communication is completed, each ordinary node employs a CSMA/CA protocol of IEEE802.11 to carry out data communication.

Disclosed is a method for data communication in a radio network, including calculating an expected value of transmission efficiency of a Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol and an expected value of transmission efficiency of a Slotted ALOHA protocol, comparing the two expected values, switching a mode into the mode of the protocol having the larger expected value from among the expected value of transmission efficiency of the CSMA/CA protocol and the expected value of transmission efficiency of Slotted ALOHA protocol, and broadcasting, to stations (STAs), a message for indicating the STAs to switch a protocol into the protocol having the larger expected value of transmission efficiency, and transmitting data by using the protocol having the larger expected value of transmission efficiency.

In the invention, wireless communication devices transmit beacon frames in an order in compliance with a CSMA/CA protocol. A wireless communication device as a transmitting station of a multicast frame uses one of the beacon frames to notify wireless communication devices as receiving stations of the multicast frame that an ACK frame is to be transmitted when the multicast frame is received. On receipt of the multicast frame, the wireless communication devices as the receiving stations transmit ACK frames in order of transmitting the beacon frames at SIFS intervals.

The invention provides a dynamic power line carrier communication channel allocation method based on TDMA and CSMA/CA, and relates to the communication field. The method is used for solving the problems that an existing power line carrier communication channel allocation method is poor in adaptivity and low in channel utilization rate. According to the dynamic power line carrier communication channel allocation method, the TDMA protocol is utilized to allocate channels to all nodes in a communication network, and when an idle time slot is generated after channel allocation is completed, the CSMA/CA protocol is utilized to allocate channels to non-main nodes. The advantages of TDMA and the advantages of CSMA/CA are combined, and the channel utilization rate is increased in the real-time changing process of the network load while network conflicts are reduced. The dynamic power line carrier communication channel allocation method can be applied to multiple fields such as smart home, building automation and rail traffic.

The present invention relates to a congestion control method for a communication system supporting layered radio channel structure for communication between at least a first communication device and a second communication device, the layered structure comprising at least a physical layer and a medium access layer. The communication system is arranged to offer a first type of service with a first priority order and a second type of service with a second priority order, in the communication system messages comprising a preamble and a payload can be transmitted between devices, each message being separated by at least a period corresponding to a minimum allowable period between two messages. In the method the first communication device first (a) generates (301) a physical layer message pertaining to the first type of service; (b) senses (303) the radio channel idle for at least a period corresponding to the minimum allowable period between two messages; and (c) transmits (305) the physical layer message comprising a special preamble indicative of the type of service the message pertains, wherein the content of the preamble is arranged to be detected by the second communication device within a communication range irrespective of the decoding state of the payload of the transmitted message.

The invention discloses a low delay intelligent substation wireless communication mechanism. The problem that message transmission delay is instable in an intelligent substation wireless network is mainly solved. The scheme comprises the fact that through utilization of a TDMA protocol, according to SV (Sampled Value) and GOOSE (Generic Object Oriented Substation Event) periodic business requirements of a substation, fixed time slots are allocated to all nodes in a communication network based on a periodic fair allocation method; and when leisure occurs in the fixedly allocated time slots, through utilization of a CSMA/CA protocol and through importing of message priorities, and channels are competed for sudden business such as barring business or other uncertain business. The invention provides a wireless communication mechanism for intelligent substation equipment. According to the low delay intelligent substation wireless communication mechanism based on TDMA and CSMA/CA mixture, delay stability of periodic messages in the intelligent substation wireless network is ensured, transmission of sudden messages is ensured, and a channel utilization rate is improved.

Systems, methods, and machine-readable media to orchestrate process-performing resources and process protocols particularized to individual resources and loads are provided. Data changes in the data streams may be detected and identified. Data items from the data streams may be aggregated. Protocols that include parameter constraints according to specifications of process performance and/or operation performance may be identified. Operation-performing resources may be modeled with metrics being a function of protocols and consolidated data portions. A composite may be created that specifies a configuration a subsystem. The composite may be transmitted, and allocation of operation-performing resources to perform the defined process in accordance with the selected protocols may be controlled.

The invention discloses a design method of a CSMA/CA (carrier sense multiple access/collision avoidance) protocol for a M2M network, and the method is characterized in that energy consumption of a node with high energy consumption is reduced in the M2M network, and the transmission reliability of data in the M2M network can be ensured when the life cycle of the mentioned node is prolonged, thus the method can be applied to the CSMA/CA protocol of the M2M network. The method comprises steps of: step 1: assigning permission to the monitoring point in the M2M network; step 2: periodically detecting the operation status of the monitoring node in the M2M network, performing step 3 under the idle state of the monitoring node, and performing step 4 under the to-be-transmitted data state of the monitoring node; step 3: performing dormancy operation to the monitoring node, and performing the step 2 after some interval of time; step 4: performing signal channel contention operation to the M2M network, acquiring signal channel use right by the monitoring node, and performing step 5; step 5: uploading the data to the monitoring node, and performing the step 2 after uploading the data.

The invention relates to a safety certification method for a smart grid AMI system. The safety certification method is suitable for the IEEE802.1x protocol certification method based on SCEP expansion of the smart grid AMI system, the SCEP is used as the certification mode of a smart grid terminal for accessing the AMI system and is used as an IEEE802.1x protocol expansion certification mode, namely, under the control of the IEEE802.1x protocol, SCEP certification can be only carried out on the non-certificated smart grid terminal by an uncontrolled port of the IEEE802.1x protocol; and the certificated smart grid terminal can access the AMI system through a controlled port of the IEEE802.1x protocol. The safety certification method provided by the invention is suitable for simple certificates and is used for guaranteeing to completely isolate the AMI system resources before the smart terminal is authorized to access the AMI system.

The invention discloses an Ethereum covert communication method based on a whisper protocol. The method comprises the steps: coverting and interacting a subject-key pair; encrypting and encoding the message T to be transmitted to obtain T '; randomly generating a statement as an effective carrier payload of a message body in a whisper protocol; carrying out character matching on the T' and a carrier, and recording index information of matched characters; encrypting the index information, and expanding the index information to enable the total length of the message to be a multiple of 256 bytesand serve as an expanded part padding of a message body in a whipper protocol; setting structure information of the whisper letter, setting a theme of the letter as an interactive theme, and encrypting the interactive theme; broadcasting letters to achieve information transmission; enabling the receiver to screen letters through the theme, and decrypt the letters by using the corresponding secretkeys to obtain payload and padding; and decrypting the padding to obtain decrypted information, namely an index, and performing information restoration in combination with the effective carrier. Themethod provided by the invention is high in security, has good anti-interference performance, tamper resistance and detection resistance, and avoids unnecessary consumption when a receiver screens data packets in combination with a theme mechanism of the whisper.

The invention discloses a data transmission method in a WiFi network, which comprises the following step: when data transmission is carried out, sending data information comprising identity authentication information to a corresponding terminal user according to a WiFi network confirmed by the identity authentication information. Meantime, the invention also discloses a data transmission system in the WiFi network. The method and system of the invention can effectively avoid collision in the WiFi network, and can solve the problem of avoiding data collision depending on increasing interframe space in the working process of a CSMA/CA protocol, thereby improving the interactive efficiency between a network side and a user terminal.

The invention discloses a distributed adjustment method for a node initial back-off window when an unlicensed frequency band is shared by LTE and WiFi. The LTE base station and the WiFi node share anunlicensed frequency band; the WiFi nodes comprise a WiFi wireless access point and a WiFi user node; the WiFi node accesses a channel by using a CSMA/CA protocol; and the LTE base station accesses the channel by using an LBT and backoff mechanism, and the LTE base station and the WiFi node adjust respective initial backoff window sizes in a distributed manner according to respective observed information so as to maximize the throughput of the LTE and WiFi coexisting network under the condition of meeting 3GPP fair limitation.

The invention relates to the field of communication, in particular to a reliable broadcasting method for a hybrid traffic system with formation as the center. According to the method disclosed in theinvention, a wireless basic service set is formed by taking unmanned formation as a center. Formation vehicles use a TDMA protocol, and other vehicles use a CSMA/CA protocol. According to the method disclosed in the invention, a part of formation members are selected as CTS responders in a basic service set; the RTS/CTS function is realized for broadcast communication of a free vehicle driven by aperson, an RTS/CTS mechanism is introduced for broadcast communication, so that the broadcast communication can have a retransmission capability, and the reliability of the broadcast communication isimproved. According to the method, the topological structure characteristics in the hybrid traffic system are fully utilized, the performance loss caused by collision in wireless communication can begreatly reduced, and therefore the network communication efficiency is improved.

The invention provides a CSMA/CA multiple access method based on a threshold service. The method comprises the following steps that a node needing to be accessed into a channel preempts the channel according to a CSMA/CA protocol; when a value of a backoff counter is reduced to 0, the node checks the length of a cache queue, and sets a value of the residual counter as the length of the cache queue; the node sends a data frame and starts the timer to record the time for waiting for ACK confirmation; whether the node receives the ACK confirmation in the ACK-TIMEOUT time or not is judged, and ifyes, the data frame is sent successfully. According to the method, the competition time delay of the node can be greatly reduced, and the data frame can be sent out once as soon as possible, so that the network throughput is improved, the average time delay and the delay jitter of the data frame are reduced, and the system stability is enhanced.

A method for enabling one or more nodes to communicate with an access point (AP) according to a CSMA/CA protocol is provided. In one embodiment of the method, when the individual node enters into a state of having at least one packet of data to be transmitted to the AP, the individual node waits for a non-zero deterministic delay so that any packet arrived during the delay is allowed to be aggregated and transmitted upon one transmission opportunity, thereby improving channel utilization. The delay is determined such that a predicted system throughput is maximized. It is found that the system throughput is significantly affected by the relationship between the delay and the number of the one or more nodes. Hence, the delay is advantageously determined according to the number of the one or more nodes. After the delay expires, the individual node initiates a contending procedure.