206 results about "Aloha" patented technology

A communication system balances message traffic between return channel groups and within the groups, so that the user does not control the specific transmission frequency used. Uplink frequencies and bandwidths for the return channels are set by the system in a return channel control message in the broadcast signal so as to account for system and return channel group loading, and to account for user message backlogs. An initial transmission from a remote user may be made using an ALOHA-type burst signal that provides a message backlog to the control station, and is made on a frequency determined from a randomly weighted, load-based frequency selection process. The system, and not the individual users determine the frequency and channel allocations. For large backlogs or priority users, periodic bandwidth is provided. A method for balancing loads among and between groups of return channels in the communication system includes requesting return channel bandwidth in an uplink message from a remote user to a control station. The uplink message may include a both a backlog indicator and a bandwidth allocation request provided to a Network Operations Center (NOC) which can be used to set the return channel bandwidth and frequency for the remote uplink. A user message is transmitted on the designated return channel frequency using bandwidth allocated in accordance with the backlog indicator and a bandwidth allocation request so that traffic loads are maintained in balance between established return channel frequency groups, and within each return channel frequency group.

A multiple access communication protocol that includes an uplink and a downlink channel is disclosed. The uplink channel has a plurality of frames, such that each frame has a first selectable number of minislots and a second selectable number of slots. A reservation request of a first type is sent into a first selected minislot of a selected frame of the uplink channel when information of a first type is to be sent. The reservation request of the first type requests an assignment for at least one slot for transmitting information of the first type in at least one frame that is subsequent to the selected frame. A reservation request of a second type is sent into a second selected minislot of the selected frame when the second selected minislot is available in the selected frame and when information of a second type is to be sent. The reservation request of the second type requests an assignment of at least one slot for transmitting information of the second type in at least one frame that is subsequent to the selected frame, and contends for the second selected minislot based on a pseudo-Bayesian Aloha algorithm. The downlink channel contains a feedback message that occurs prior to the end of the selected frame of the uplink channel. The feedback message includes minislot assignment information for sending reservation requests of the first and the second type and slot assignment information for transmitting information of the first and the second type, minislot contention information for the reservation requests of the second type sent in the selected frame, and reservation backlog information for an estimated number of reservation requests of the second type pending at a beginning of the selected frame.

A first aspect of the invention is a method of transmitting data packets over a transmission channel shared by a plurality of users, based on the time and/or frequency diversity slotted Aloha technique, in which at least two replicas of each packet to be transmitted are sent over said transmission channel, wherein each replica transports signaling information enabling the other replica(s) of the same packet to be located in the time and/or frequency domain. A second aspect of the invention is a method of recovering packets in the receiver, the method exploiting said signaling information to execute an interference cancellation algorithm for recovering packets corrupted by collisions caused by access conflicts. Other aspects of the invention are a transmitter equipment and a receiver packet recovery equipment adapted to use said methods.

The invention pertains to the radio frequency identification technical field, in particular relates to a time slot ALOHA anti-collision algorithm which is applicable to the dynamic environment. The algorithm comprises the following steps that: the initialization is firstly carried out, and the detection of whether a termination command emitted by an upper computer is received or not; if the termination command is received, the algorithm is finished; otherwise, the data receiving is started, the number of the space slot, the time slot, the collision time slot and the success time slot are respectively carried out the statistics; whether a time slot counter and a 2<q> taking model are equal to 0 or not is judged, if equal to 0, the number n of labels is estimated, Q' is calculated, whether Q' is equal to Q or not is judged, if the two are equal, a new frame is started; if not, the new Q value is calculated, and then the algorithm returns to carry out the next round of identification process. The algorithm takes account of the factor of the change of the number of the labels, a reader can terminate the inappropriate frame as soon as possible and select the more reasonable frame length for the next from by calculating the number of the labels in a calculation field zone and judging whether the current frame length is appropriate or not during the identification process of the current frame, thus reducing the probability of occurrence of the collision of the labels and improving the identification speed of the reader under the dynamic environment.

Provided is a method for estimating the number of tags in a slotted Aloha-based RFID system, which can estimate the number of tags through a new statistical average scheme using the number of slots, the measured number of empty slots, and the measured number of ID slots. The estimating method includes the steps of: a) setting the number (N) of slots, the measured number (c₀) of empty slots, and the measured number (c₁) of ID slots as parameters; and estimating the number (n) of the tags by substituting the set values into n=(N−1)/(c₀/c₁).

The invention discloses a superframe-based efficient media access control method in a wireless body area network, mainly solving the problems that an IEEE (Institute of Electrical and Electronic Engineers) 802.15.4 protocol is incapable of distinguishing service priorities and has time slot waste in a non-competitive period in a wireless body area network. The superframe-based efficient media access control method is realized by adopting the steps of: in a competitive period, setting the competitive period into a high priority service dedicated time slot H, a high priority service spare time slot h and a common time slot by adopting a time slot ALOHA competition mechanism based on the service priority, wherein a common node adopts the three different competition mechanisms according to the quantity of high priority services in the current superframe competitive period; and in a non-competitive period, ensuring that allocation and utilization of a GTS (Guarantee Time Slot) service are carried out by utilizing a micro time slot as a unit and adopting a micro time slot mechanism so as to realize the effective utilization of the time slot. Compared with the IEEE 802.15.4 protocol, thesuperframe-based efficient media access control method disclosed by the invention can not only ensure that the high priority service is transmitted with a higher success probability, but also effectively improve the time slot utilization ratio in the non-competitive period and is suitable for the wireless body area network.

The invention discloses a self-adaptive media access control (MAC) protocol for a vehicle-mounted wireless self-organized network, comprising a DR-ALOHA protocol which is used by a control channel and a strategy for accessing a business channel through a node dynamic selection competition method or a pre-reservation method, wherein the DR-ALOHA protocol dynamically adjusts the number of fixed-length time slot in a time division multiplexing principle so that the secure information of all nodes in a network can be transmitted reliably in real time, and is applicable to networks with the node density and the topological structure being dynamically changed; in the strategy of accessing the business channel through the node dynamic selection competition method or the pre-reservation method, firstly the switching threshold of a business channel access method is determined by theoretical analysis and mathematical deduction and then the business channel is accessed through the node dynamic selection competition method or the pre-reservation method by integrating the real-time channel utilization rate of the business channel, so that the channel utilization rate of the business channel can be the highest in any node density.

The invention relates to a multi-tag identification method of an RFID reader. The method comprises the following steps: 1) a reader sends detection commands to a tag group, each tag randomly selects one time slot number from the time slot sequence ranging from 0 to 2Q-1 after receiving the detection commands and generates one binary data with 2Q-numbered bits as the time slot sequence of the corresponding tag; 2) after the reader receives the time slot sequences sent by the tags and detects the bit conflict of the time slot sequences of the tags; and 3) the reader begins to identify the tags according to a non-idle time slot number table entry and successively sends query commands Query (S1) to the tag group from small to large order of the slot sequences numbers. Thebeneficial effects of the invention are as follows: the invention inherits the high recognition rate characteristic of the binary tree algorithm, and combines the high identifying accuracy advantage of the binary tree algorithm and the fast identification advantage of the random aloha algorithm during the identification process of the tags.

An RFID (radio frequency identification) anti-collision method based on GASS (grouped adaptive allocating slots) comprises steps as follows: firstly, a reader performs scanning statistics on slots randomly selected by tags and sends the slots to all the tags, then the tags perform corresponding slot adjustment, the reader skips free slots and collision slots and allocates effective slots adaptively, the tags are quickly identified, and when the number of unidentified tags is larger, the algorithm adopts strategies such as grouping, dynamic frame length adjustment and the like to shorten slot processing time. Simulation results indicate that with the adoption of the method, the identification efficiency and stability of a system are improved, the transmission cost is reduced, particularly when the number of the tags exceeds 1,000, the throughput of the algorithm is still kept higher than 71%, the efficiency of the system is 300% and 97.2% higher than that of a system adopting a traditional frame-slotted ALOHA-256 algorithm and that of a system adopting a grouped dynamic frame-slotted ALOHA algorithm respectively, and the method has practical application values for rapid identification of Internet-of-Things tags.

A novel method for dynamic load management of random access channels (also known as Aloha channels) in shared communications systems, such as satellite (4), cable, and wireless communications networks is provided. The method provides algorithms and procedures to accurately estimate traffic load offered by multiple distributed terminals (1a, 1b, . . . 1n) into the channel (2). And also provides for regulating traffic so that the channel (2) is not overloaded. The traffic load management algorithms can be done at a central site, such as a Network Control Center (3) or a cable head-end. Alternatively, traffic load management can be done in a distributed manner by all terminals. Traffic regulation is done in a fair manner across all terminals. The algorithms are designed for efficient implementation in software and/or hardware.

The invention provides a method for identifying a lost tag of an RFID system. The method for identifying the lost tag of the RFID system comprises the steps that a Bloom filter is used, the property whether an element exists in a set or not can be searched for, and tags in a set of an expected classification are activated to participate in the follow-up identification process; an empty time slot and a conflict time slot are made full use of on the basis of an ALOHA protocol, and identification of the lost tag in the classified RFID system is finally accomplished. According to the method for identifying the lost tag of the RFID system, the process of identifying the lost tag can be carried out by screening out the tags of the expected classification, the utilization rate of frames in the identification process is improved, and identification efficiency is greatly improved.

The invention discloses a high-efficiency multi-tag anti-collision radio frequency identification (RFID) method, which mainly comprises a tag division process and a tag searching process. An ALOHA frame or other signal frames are established in the tag division process; and in the tag division process, time slots are randomly selected for tags to transmit IDs, and function in dividing a tag group consisting of all the tags in the range of a reader-writer into a plurality of independent small tag groups. In the tag searching process, a plurality of message frames are involved; and each frame corresponds to a specific collision time slot in the tag division process, and in the frame, the tags can be identified one by one by a backtracking binary-tree searching method and the like. The method can greatly reduce collision phenomena in a multi-tag identification process and reduce times of information interaction between the tags and the reader-writer, and ensures high efficiency and security.

The invention discloses a multi-label anti-collision method based on a grouping mechanism and jumping dynamic binary recognition used in an RFID system. The method comprises a label estimation phase and a label recognition phase, wherein in the label estimation phase, labels are grouped randomly, a first group of labels are recognized by adopting the jumping dynamic binary algorithm, and then the estimation of the quantity of unrecognized labels are completed according to the characteristics that the quantity of each group of labels are in accordance with even distribution; in the label recognition phase, a second grouping quantity, i.e. the optimal grouping conducted on the rest groups of labels is determined; in the recognition process, jumping dynamic binary algorithm is adopted to recognize collision labels, so as to recognize all the labels. The invention combines the advantages of binary tree algorithm and Aloha algorithm, thus greatly reducing the quantity of collision labels in the early and later phases of recognition. The invention has simple structure, rapid recognition speed, low complexity and label power consumption, thus being applicable to RFID system.

A method and device for selecting one or more transponders, in particular backscatter-based transponders, from a plurality of transponders by a base station, which method is based on a slotted ALOHA method, in which the base station defines numbered time slots and a random number generated in a given transponder determines a time slot when the transponder transmits its transponder-specific identification to the base station. The random number is generated in a given transponder with the aid of a random number generator, the relevant random number generator is switched into a counter operating mode after reception of a selection command transmitted by the base station, while a count state of the random number generator is decremented or incremented when the base station transmits the start of a time slot, the relevant transponder transmits a transponder-specific identification to the base station if the count state of its random number generator is equal to a predetermined value, and the relevant random number generator is then switched back into the operating mode for random number generation.

The invention discloses a self-adaptive competition window adjusting algorithm based on interference analysis and belongs to the technical field of wireless communication. The method is suitable for a time slot Aloha mechanism and comprises the steps of: determining a competition window value and back-off time, namely counting collision times and successful times in a period, acquiring corresponding channel busy indexes according to the counted values, and updating the competition window value according to the channel busy indexes when a next period begins; and determining back-off time, namely performing interference analysis on all nodes, determining a neighboring node number of each node and accordingly acquiring a quantile, and choosing the back-off time according to the quantile values when the nodes are successfully sent or collided. According to the self-adaptive competition window adjusting algorithm, the interference analysis is used for choosing the back-off time, so that the algorithm is low in complexity, and network time delay and collision probability are effectively reduced, and throughout performance is improved.

Methods, algorithms, architectures, circuits, and/or systems for managing POR-less integrated circuits are disclosed. The method of validating code from a wireless device can include: (i) broadcasting a signal from a reader to the wireless device, (ii) reading a code transmitted, re-radiated, and/or backscattered from the wireless device, the code having a predetermined quality, characteristic, and/or property, (iii) comparing the code to a reference quality, characteristic, and/or property, and (iv) validating the code when the predetermined quality, characteristic, and/or property matches the reference quality, characteristic, and/or property. Embodiments of the present invention can advantageously provide a reliable approach for validating integrated circuits that do not incorporate a POR circuit, and which therefore may transmit spurious bits of data upon being energized. In addition, embodiments of the present invention advantageously allow an Aloha-type anti-collision function to be implemented in a reader based on POR-less integrated circuits.

PCT No. PCT/SE96/00299 Sec. 371 Date Apr. 28, 1998 Sec. 102(e) Date Apr. 28, 1998 PCT Filed Mar. 7, 1996 PCT Pub. No. WO96/31077 PCT Pub. Date Oct. 3, 1996The present invention concerns a process in a radio communication system which is arranged for packet data transmission according to a message-synchronized ALOHA protocol with reservation. Mobile stations in the system are arranged to send access requests to a base station during a reservation phase in a mobile radio system which uses this protocol. The base station is arranged to receive and comply with the access request from a first mobile station by sending thereto a channel reservation message (2) comprising a channel reservation (3). The base station is further arranged to receive access requests from at least a second mobile station for which channel reservation momentarily cannot be carried out. According to the process of the invention an access request received from the second mobile station is confirmed when channel reservation cannot be carried out in the usual manner. The confirmation is sent in the form of an access confirmation (4, 5) which is included in the same channel reservation message (2) as the channel reservation (3) for the first mobile station.

There is disclosed for use in a narrowband wireless messaging network, a subscriber communication unit that uses a miscellaneous ALOHA message to transmit predefined messages and/or formatted telemetry data to a base station. The subscriber communication unit comprises a transceiver for receiving messages from the base station in a forward channel and transmitting messages to the base station in a reverse channel. The reverse channel is divided into a plurality of scheduled transmission time slots and a plurality of unscheduled transmission time slots of the ALOHA type. A message controller receives input data generated by the subscriber communication unit and translates the input data into a reverse channel message capable of being transmitted in an available unscheduled time slot, such as a miscellaneous ALOHA message time slot.

A user control channel for a wireless digital subscriber line systems and the like, or other communications systems which can benefit from a control channel which provides a low data rate connection between stations on an ongoing basis, makes efficient use of transmission capacity in the communications systems. In one embodiment, the user control channel has a structure employing slotted frames, and a user can be assigned multiple slots, a single slot or less than a single slot (sharing slots with other users) to meet the data transmission needs of the user. Also, one or more slots can be designated as random access slots which users can access via an Aloha-like or other random access protocol as needed.

The embodiment of the invention provides an access control method and an access control device. The method comprises the following steps of: counting the number of users accessed successfully within the preset time period; determining the number of users accessed successfully each time slot on average according to the number of users accessed successfully in the preset time period and the total number of time slots within the preset time period; based on a slotted ALOHA model, determining the average value of the number of users tried to be accessed each time slot of a first candidate and a second candidate which correspond to the number of users accessed successfully each time slot on average; selecting one of the average values of the numbers of users tried to be accessed each time slot of the first candidate and the second candidate; and determining the accessed control parameters and/or modes according to the average value of the number of users tried to be accessed each time slot actually, and carrying out access control according to the determined access control parameters and/modes. The method and the device provided by the embodiment of the invention can determine the average value of the number of users tried to be accessed, and the access control modes or parameters are arranged accordingly, thus the access control is carried out effectively, and the jamming of an access network and a core network is reduced.

The invention discloses a multichannel MAC protocol implementation method in a service-intensive type vehicle-mounted network, and belongs to the field of vehicle-mounted wireless communication. The method comprises the steps: distributing a DS-ALOHA control channel access protocol and a service channel time slot, wherein the DS-ALOHA control channel access protocol employs a TDMA mechanism; introducing the concept of cluster; collecting and transmitting safety information through the cluster, thereby enabling the safety information in the network to be transmitted safely in real time; meanwhile, distributing the access of a service channel through the cluster, thereby reducing the collision among nodes, and improving the utilization rate of a business channel. The method just needs to use a single antenna to achieve the multi-channel communication, and more effectively uses wireless channel resources. Meanwhile, compared with a multi-antenna scheme, the method reduces the production cost, and reduces the energy consumption caused by the detection of safety information. The method can guarantee the reliable transmission of the safety information under the service intensive network, and improves the throughput of the system for the service information.

Provided are an anti-collision system and method which address the mobility of radio frequency identification (RFID) tags. An RFID reader may transmit an identification start command to identify a plurality of RFID tags in an identification area of the RFID reader. The RFID tags compare the number of collisions of each RFID tag receiving the identification start command with a collision threshold C_th and attempt to be identified in a binary tree section of a frame or in a framed slotted ALOHA (FSA) section of the frame based on the comparison.