207 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.

Multiple field units in a CDMA system are synchronized for communication with a base station using shared forward and reverse link channels. In an illustrative embodiment, each field unit is assigned a time slot in a forward link channel to receive messages from the base station. Likewise, each field unit is assigned a time slot on a common reverse link channel for transmitting messages to the base station. Timing alignment and power level control among each of many field units and the base station is achieved by analyzing messages received at the base station in a corresponding time slot as transmitted by each field unit. Thereafter, a message is transmitted from the base station in a corresponding time slot to a particular field unit for adjusting its timing or power level so that future messages transmitted from the field unit are received in the appropriate time slot at the base station at a desired power level. In this way, minimal resources are deployed to maintain communication and precise synchronization between a base station and each of multiple users, minimizing collisions between field units transmitting in adjacent time slots on the reverse link. This method reduces the frequency a field unit must rely on the use of a slotted aloha random access channel according to IS-95.

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).

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 system and method are provided for reliable, wireless group alerting in a system having a database, switch, wireless network, and a plurality of intelligent mobile receivers, and preferably employing a modified two-way paging based on ReFLEX™ protocol information service (IS) messages and a novel ALOHA command for multicast acknowledgement from mobile receivers. An encrypted message is broadcast to a group address and received by a selected number of the mobile receivers. The network replies to the sender with detailed information about the individual members in the alert group. Each of the mobile receivers in the group then acknowledges the common message back to the system, decrypts the message, displays it to the user, and allows the user to respond. The system employs centralized management to simplify the roles of the mobile users and administrators, minimizing configuration and operational human errors that would otherwise result in confusion or lost messages.