184 results about "Carrier-sense multiple access" patented technology

An improved method of network management, particularly in the context of standards IEEE802.11 and IEEE802.11k, through two new MAC measurements, with attendant advantages. The two new measurements include WTRU uplink traffic loading measurement, and an AP service loading measurement and is generally applicable at least to layers 1 and 2 as applied to a least 802.11k in the context of OFDM and CDMA 2000 systems, but is applicable to other scenarios as well. A Method for determining and advertising congestion is also provided for a Wireless Local Area Network (WLAN) system. The present invention also introduces a method for managing congestion when congestion is detected. This aspect of the present invention applies primarily to wireless systems that use the Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) mechanism. The methods are advantageously implemented in selectively configured WTRUs of various forms.

Systems and methods which control communications in a carrier sense multiple access environment to provide a balance between communication sensitivity and transmission availability are shown. Adaptive interference control techniques of embodiments operate to determine a media error time metric representing the time associated with receiving interfering signals. The media error time metric of embodiments is used to adjust operation of various network systems in order to adjust communication sensitivity and / or transmission availability. Desensitizing thresholds and sensitizing thresholds may be used to define operating boundaries, such that desensitizing thresholds are used to control network desensitize actions which result in decreased error times and sensitizing thresholds are used to control network sensitizing actions which result in increased error times. Error time metrics and corresponding desensitizing and sensitizing thresholds may be utilized with respect to a plurality of radios. Embodiments provide for adjustment of control parameters based upon historical operation.

Provided is a method of dividing a payload intra-frame for improving throughput of a carrier sensing multiple access / collision avoidance (CSMA / CA) wireless communication network. The payload intra-frame dividing method includes a data frame dividing step and a physical layer frame generating step in which a physical layer receives a plurality of data frames from an upper layer within a range of the maximum data frame length the physical layer can transmit and transmits the data frames as a single physical layer data frame. Furthermore, an acknowledge (ACK) frame is provided, which can minimize the deterioration of throughput even when a data frame, which has been divided into a plurality of data frames and transmitted as a single data frame, is required to be re-transmitted because an error is generated in the data frame.

A wireless communication network includes a network coordinator (NC) having plural channels and plural wireless transceivers, and plural nodes. Each node has status information, a number of channels and a number of wireless transceivers. Each node and the NC communicate in a Carrier Sense Multiple Access mode. Each node communicates the status information thereof to or toward the NC in a Time Division Multiple Access mode having plural time slots. The NC assigns the time slots and the channels to the nodes to provide a plurality of collision-free schedules therefor. The NC sends, for each node, a corresponding one of the collision-free schedules to or toward a corresponding one of the nodes. Each collision-free schedule includes a corresponding number of the time slots and a corresponding number of the channels that the corresponding one of the nodes employs to communicate the status information thereof to or toward the NC.

IEEE 802.11 power management scheme for an ad hoc network is based on the Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) access procedure to transmit / receive their data frames. CSMA / CA may waste the scarce energy and bandwidth due to frame collisions and lengthen the frame delay due to waiting backoff time. In addition, IEEE 802.11 power management scheme does not specify how to tune the ATIM window size in a beacon interval. However, the ATIM window size affects the power consumption and throughput of a network considerably. The fixed ATIM window size cannot always accommodate the various traffic conditions. To conquer these problems and to improve the performance of networks, we propose a energy efficient MAC protocol for IEEE 802.11 networks by scheduling transmission after the ATIM window and adjusting the ATIM window dynamically to adapt to the traffic status.

A system and method for achieving enhanced CSMA / CA which improves channel availability and quality of service (QoS) in a wireless communications network. The system and method establish channels to enable communication between nodes in a communication network, based on the relationship between the average time length of message data packets and the time lengths of the request to send and clear to send messages. A node of the communication network places a data packet at a location in a queue for retransmission based on a type of information contained in the data packet if the destination node for which the data packet is intended is unable to receive the data packet. The location in the queue is indicative of a duration of time that the node will delay before attempting to resend the data packet to the destination node.

A communication bandwidth is divided into a beacon period in which all master stations compete for transmission of a beacon packet, a first carrier sense multiple access (CSMA) period in which only authorized specific stations are allowed to compete for access, and a second CSMA period in which all stations are allowed to compete for access. The master stations exchange information with each other about a communication bandwidth being used in the first CSMA period, thereby calculating a communication bandwidth which can be used by each communication system in the first CSMA period, based on the information.

A method for controlling transmit power of a node in wireless network, such as, e.g., an ad-hoc wireless network operating in accordance with a carrier sense multiple access (CSMA) protocol and where asymmetrical radio links may exist. During a request to send (RTS) and clear to send (CTS) exchange between a first node and a second node, both a request to send (RTS) packet and a probing request to send (PrRTS) packet are transmitted from the first node to the second node. The transmit power and data rate of the PrRTS packet may be different from the transmit power and data rate of the RTS packet. In response, the second node returns a CTS packet that includes a signal to noise ratio (SNR) for both the RTS packet and the PrRTS packet. A correction factor for data transmit power is then computed based in part on both the SNR for the RTS and the SNR for the PrRTS, and a data packet is thereafter transmitted at a power level that has been modified in accordance with the correction factor. The correction factor may further aid the estimation of the signal-to-noise-and-interference ratio (S / (N+I)) at a receiving node, which enables a sending node either to overcome the interference by adjusting the transmit power or avoid the interference by not accessing the channel until it hears the node again.

A method for effectively implementing real time multimedia data transmission in an Ethernet network that operates in a CSMA / CD (Carrier Sense Multiple Access / Collision Detect) scheme. Real time data gets priority over general data, and uses an MPCP (Multi-Point Control Protocol) of the IEEE 802.3ah EPON to prevent a collision from occurring in real time data transmission, and also prevents delay time variation. An RT-IFG (Real Time Inter-Frame Gap) is defined for real time data, shorter than an IFG, to give priority to the real time data over general Ethernet data. The MPCP is used for transmission of real time data without collision between the real time data.

The present invention protocol offers guaranteed Quality of Service (QoS) for a predetermined number of circuits in a highly dynamic, scalable network. The present invention protocol employs a Time Division Multiple Access (TDMA) reservation scheme to transmit deterministic data (e.g., image data) to a destination, while utilizing a Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) contention scheme to support non-deterministic data traffic. The protocol operates over a link-state based routing protocol that reliably floods routing and resource reservation information to the nodes in the network. Moreover, the present invention capitalizes on certain properties of a radio, such as a RAKE type receiver, to enable simultaneous re-transmissions of resource and route reservation information to constructively interfere and enhance the strength and range of the signal.

A carrier sense multiple access method capable of improving throughput in a wireless network is disclosed. This method is implemented in a wireless network—for example, a wireless LAN (100)—having an AP (110) that is equipped with a multi-beam antenna (111) that forms a directional beam and that is capable of SDMA, and a STA (120, 130, 140) that communicate with the AP (110). With this method, the AP (110) allots the STA (120 to 140) to a beam group defined by a coverage area of the directional beam, according to the location of the STA (120 to 140). Then, the allocated STA (120 to 140) is assigned a signature signal for group identification, the signature signal being unique to the group.

This invention discloses an adaptive dormancy method for a separated cluster structure radio sensor network data link layer, which starts up the head in network and radio communication devices for collecting nodes to initiate them at the sending or intercepting state, if no data frames are sent or received by the ordinary nodes in the cluster, the device can be turned off to enter into the dormancy state and a carrier intercepting multipath access mode avoiding conflict is applied between the head and ordinary nodes, which puts forward a system that nodes alter the time of dormancy adaptively along with dortmancy times based on binary index and a system of sending cluster head transmission instruction chart management frames periodically by cluster heads, so the radio sensor network can work under single channels asynchronously to ease up the collide and re-tansmission of nodes in the synchronous mode and too many synchronous control signalings.

The invention discloses a time division multiple access / frequency division multiple access (TDMA / FDMA)-based wireless sensor network (WSN) medium access control (mac) layer scheduling method. By the scheduling method, channels are distributed by using a time division multiplex (TDM) system in clusters and a frequency division multiplex (FDM) system among the clusters aiming at a clustering-based data collection type WSN network. The TDM system and the FDM system favorably overcome the defect of a large number of access conflicts of a contention type mac scheduling method under the condition of high network load. Meanwhile, by the novel mac scheduling method, carrier sense multiple access (csma) time slots are introduced at a communication stage in the clusters, so that the defect of low expansibility of the TDMA scheduling methods is overcome. A node revives in an active period to forward data and enters a dormancy state in an inactive period, so that the energy consumption is lowered. According to the conditions of the network load, by the scheduling method, the duty ratio of the active period in the communication cycle can be automatically adjusted, the dynamic requirements of the network on throughput can be met, and the time delay of the data is reduced to a certain extent.

A method and a target node for preventing collisions between networks communicating based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme, are provided. The method includes synchronizing an object network with a neighboring network. The method further includes allocating, to the object network, a slot index based on a number of the networks, and a contention window (CW) size. The method further includes setting, for the object network, a back-off counter value based on the CW size. The method further includes reducing the back-off counter value based on a channel state of the object network, and the slot index. The method further includes transmitting data related to the neighboring network based on the back-off counter value.

A medium access control method of a CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) based wireless LAN (Local Area Network) provides contention-free medium access authority to a station or access point receiving a request signal by: transmitting a request signal frame from an arbitrary station to another arbitrary station or to an access point via a medium occupied in transmission contention with a CSMA / CA algorithm using a DCF (Distributed Coordination Function) interframe space; and transmitting an acknowledgment signal frame from the station or the access point receiving the request signal frame to the station transmitting the request signal frame via an occupied medium using a short interframe space.

A method and apparatus are described for performing channel aggregation to communicate over a non-contiguous spectrum, such as television white space (TVWS), using a plurality of aggregated channels including a primary channel and at least one non-primary channel (e.g., a secondary channel, a tertiary channel or a quaternary channel). Carrier sense multiple access (CSMA) may be performed on the primary channel to obtain access to the primary channel. After waiting an arbitration interframe space (AIFS) and potentially performing backoff on the primary channel, the aggregated channels may be used for transmission. A buffer controller may be used to create, for each of a plurality of access classes (ACs), a logic buffer for each of the channels. A frame controller may be used to provide the buffer controller with aggregated medium access control (MAC) protocol data unit (A-MPDU) frame information, and control aggregation and fragmentation processes.

The invention relates to a wireless ad hoc network communication method and device. The method sends data to a node through a wireless ad hoc network and receives the data sent by the node through thewireless ad hoc network. Wherein the wireless ad hoc network is a frame structure of a mixed frame of a CSMA / collision avoidance CA and a time division multiple access TDMA through a carrier sense multiple access, In signal processing of LTE transmission link, encoding, diversity control and anti-jamming control are combined. In signal processing of LTE reception link, decoding, diversity controland anti-jamming control are combined, andAdaptive routing algorithm across protocol layer is added to realize centerless multi-hop wideband wireless mesh network. The wireless ad hoc network is a peer-to-peer network, all nodes in the network are equal in status, nodes can join and leave the network at any time, the failure of any node will not affect the operation of the whole network, and theinvulnerability of the network is improved.

The invention provides a networking method of a wireless sensor network. A way of combining carrier sense multiple access (CSMA), time division multiple address (TDMA) and multi-channel technology is mainly utilized for sequentially finishing confirmation of cluster head nodes and overall situation communication time slots of the cluster head nodes, and confirmation of each cluster member node in each cluster and cluster internal communication time slots of each cluster member node, forming time of each cluster is shortened, and therefore fast networking can be achieved. Moreover, a plurality of clusters can communicate on different component channels in the same time period without mutual interference, networking time of the whole network is shortened, delay time of data transmission of each cluster is shortened, the cluster member nodes upload data in the fixed different time slots, and data collision within the clusters does not occur. The feasible networking method is provided for engineering design, and can be applied to the wireless sensor network with densely-distributed sensor nodes.

The invention provides a method for controlling multiple air-conditioned indoor units by using a single wire control device. The method comprises the following steps: (1) connecting wires and sending out an order; (2) receiving the order and analyzing the order; (3) forwarding the order; (4) executing and feeding back; (5) returning an execution result. A control signal can be sent based on a CSMA / CD (carrier sense multiple access / collision detect) protocol, the order of the wire control device can be sent through indoor and outdoor buses, and one single wire control device can control multiple indoor units only by virtue of one connecting wire, thus the installation cost and material cost can be effectively reduced, and the phenomena of chaos communication and mistaken operation caused by control of multiple connecting wires can be avoided.

The invention discloses a method and a device of remote uderwater acoustic communication. The device comprises more than one underwater communication nodes and more than one abovewater communication buoys which are responsible for communication with more than one underwater communication nodes within a set distance range through an underwater acoustic channel; and the communication connection is carried out between the abovewater communication buoys through a land wireless channel. In the method, the multi-frequency band combination is adopted to sent data in parallel, and the remote communication is realized by uniting the communication buoys; in the remote communication, a three-time handshake protocol in the carrier sense multiple access (CSMA) needs not to be used in the communicationbetween the underwater communication nodes and the buoys, while a channel can be directly monitored in a full frequency range; the data are synchronously sent to the abovewater communication buoys inparallel on each subchannel on the monitored idle channel by utilizing a frequency modulation method; and the data is transmitted by the abovewater communication buoys through a radio wave manner. Bythe method and device provided by the invention, one-time successful transmission probability of the two parties of the communication can be improved, and the anti-interference performance of a system is enhanced.

An apparatus and method for deciding a handover in a dual mode portable terminal supporting a cellular network and an unlicensed ISM (Industrial, Scientific and Medical) band network based on a Carrier Sensing Multiple Access with Collision Avoidance (CSMA / CA) scheme is provided. The method includes checking for an available throughput of an Access Point (AP) by analyzing a signal received from the AP of the unlicensed-band network while using the cellular network; determining whether the AP can provide a service provided through the cellular network by using the available throughput of the AP; and if it is determined that the AP can provide the service, deciding whether to handover to the AP by measuring a strength of the received signal.

An electronic device may be operable to control access to a physical medium (e.g., airwaves, a copper cable, or an optical fiber) utilizing carrier sense multiple access (CSMA). The amount of time that the electronic device must sense the physical medium as being inactive before it permits transmission of a message onto the physical medium may be determined based on: the size of the message, the type of the message, the symbol rate at which the message is to be transmitted, and / or a channel onto which the message is to be transmitted. Similarly, other aspects of how and when electronic device transmits and / or receives on the physical medium may be controlled via one or more dynamically configurable parameters which may be configured based on characteristics of received and / or to-be-transmitted messages.

The invention discloses a wireless communication system, which is provided with a control node and a plurality of user nodes, wherein each user node is provided with respective priority; the user nodes can access a channel in a universal access time period and special access time periods which correspond to the respective priority; in the universal access time period, each user node accesses the channel in a carrier sense multiple access / collision avoidance (CSMA / CA) mode; each special access time period has the corresponding priority; each special access time period can correspond to one or more priorities through system configuration; and when one special access time period corresponds to only one priority, only the user node which corresponds to the priority are allowed to access the channel in the current special access time period.

A method and apparatus for measuring the quality of wireless channels based on a result obtained by measuring contentions between stations in a wireless network employing a carrier sense multiple access / collision avoidance (CSMA / CA) medium access control (MAC) method specified in the IEEE 802.11 standard are provided. The method includes determining contentions between stations to transmit frames via a wireless channel that uses a contention-based medium access method, and measuring the quality of the wireless channel based on the determined contentions.

The invention provides a cross-layer communication method for an OFDM (Orthogonal Frequency Division Multiplexing) link physical layer and an MAC (Media Access Control) layer of an underwater acoustic communication network. Based on the purposes of reasonably allocating channel resources and improving the throughput of the network, the performance of the network is optimized by a cross-layer data interaction method for a physical layer and an MAC layer. The physical layer adaptively adjusts the modulation order, coding rate and frequency diversity order according to an underwater acoustic channel environment, thus realizing data transmission of different rates to adapt to a fast time-varying underwater acoustic channel; the MAC layer adopts an improved CSMA (Carrier Sense Multiple Access ) / CA (Collision Avoidance) protocol, thus improving the retransmission success rate of data packets and reducing the data transmission delay; and the cross-layer design between the physical layer and the MAC layer solves the problems of high packet loss rate and low transmission efficiency caused by fast time variation, long transmission delay and other factors of the underwater acoustic channel, thus improving the throughput of the underwater acoustic communication network and the spectral efficiency of the system.

The invention discloses a visible light local area network duplex communication method and relates to the technical field of visible light communication. In the method, up transmission of data is performed when an access point is turned off; a terminal sends a request frame to the access point at first and sends a data frame after receiving a response frame of the access point; and down transmission of the data is performed when the access point is turned on; and the data to be sent is modulated on light of the access point and broadcast. By the visible light local area network duplex communication method, an uplink and a downlink of a visible light local area network can work in a visible light wave band and two different technologies in the uplink and the downlink can be avoided, so the technical complexity of the local area network is reduced. In the uplink, a carrier sense multiple access / collision avoidance (CSMA / CA) protocol is adopted, so multiple access of the point is realized; and a requesting-authorizing mechanism can be used for distributing an up bandwidth, so hidden stations during wireless communication can be avoided.

The invention discloses an electric power data multi-way communication system. The electric power data multi-way communication system comprises a main station terminal, a PLC (programmable logic controller) network, a centralizer and a meter, wherein the main station terminal, the centralizer and the meter are subjected to communication and coupling through the PLC network. The electric power data multi-way communication system further comprises a centralizer end module arranged at the centralizer end as well as a meter end module arranged at the meter end; the centralizer end module is connected with the meter end module through an electric power line protocol. The invention also discloses a multi-way centralized meter reading system. According to the electric power data multi-way communication system and the multi-way centralized meter reading system disclosed by the invention, communication modules are intelligent nodes, and intelligent modules interact for instant networking, and the networking is not controlled by the centralizer; real-time, rapid and stable communication is achieved; the antidamping and noise resistant capabilities of the systems are improved further on the networking mechanism based on a physical layer by fully utilizing the intelligent characteristic of a chip of the physical layer; the technical difficulties of network time and sequence, network conflict, network efficiency, effective detection of repeated data packets and the like are solved based on the chip CSMA (carrier sense multiple access), and the stability and reliability of communication are ensured.

Determination of a transmission through a network having a plurality of nodes using carrier sense multiple access collision avoidance (CSMA / CA) may be performed by broadcasting a route request (RREQ) packet from a source node that is targeted towards a destination node within the network, such that the RREQ is received by a first set of nodes in proximity to the source node. After first receiving a RREQ, each of the plurality of nodes rebroadcasts the RREQ after waiting a randomized amount of wait time. During each randomized wait time, the node suppresses all but one RREQ received by the node during the wait time.