A communication apparatus includes: a data generating unit that generates write data to be sent to any other communication apparatus at an arbitrary timing; a communication unit that repeatedly sends a read request to the other communication apparatus until the write data is generated and, at the same time, repeatedly receives a read response sent from the other communication apparatus in response to the read request; and a data acquisition unit that acquires read data, which is sent along with the read response by the other communication apparatus, when the read data is generated at an arbitrary timing by the other communication apparatus.

Systems and methods are described that collect spatio-temporal data using an RFID system that is capable of locating the spatial position of a sensor, which is typically unaware of its location. Such systems and methods can be contrasted with conventional RFID systems in that they are able to determine the location of sensors in space as opposed to with respect to read zones related to the underlying RFID reader infrastructure. One embodiment includes an RFID system having a plurality of read zones and configured to obtain the spatio-temporal state of sensors within a sensor cloud, where the spatio-temporal state of each sensor includes sensor information, a time stamp, and a spatial location specified independently of the read zones of the RFID system, a spatio-temporal database configured to store spatio-temporal state of a plurality of sensors over time, and an application server configured to trigger events based upon the detection of at least one condition by applying at least one filter to the data within the spatio-temporal database.

A method and apparatus are disclosed that apply multiuser detection (MUD) analysis to an aggregated RF response from a plurality of simultaneously queried RFID tags, so as to distinguish the individual tag responses. The claimed method thereby significantly reduces RFID detection latency when multiple tags are simultaneously queried. Some embodiments transmit carrier waves at more than one frequency, such as a plurality of equally-spaced frequencies, so as to enhance the MUD analysis by incorporating a multi-frequency dimension. Other embodiments incorporate additional spatial dimensions by deploying multiple RF detection antennae at separated locations. The number of colliding tag responses must be estimated before MUD analysis can be applied. In some embodiments other signal parameters must be estimated, such as signal bias and an impulse function for each responding tag that characterizes alterations of the RF signal while in transit due to propagation distance, passage through intervening objects, and reflections.

Systems and methods are described that collect spatio-temporal data using an RFID system that is capable of locating the spatial position of a sensor, which is typically unaware of its location. Such systems and methods can be contrasted with conventional RFID systems in that they are able to determine the location of sensors in space as opposed to with respect to read zones related to the underlying RFID reader infrastructure. One embodiment includes an RFID system having a plurality of read zones and configured to obtain the spatio-temporal state of sensors within a sensor cloud, where the spatio-temporal state of each sensor includes sensor information, a time stamp, and a spatial location specified independently of the read zones of the RFID system, a spatio-temporal database configured to store spatio-temporal state of a plurality of sensors over time, and an application server configured to trigger events based upon the detection of at least one condition by applying at least one filter to the data within the spatio-temporal database.

RFID readers and methods for adjusting a query command slot-count parameter Q for use by radio frequency identification (RFID) tag reader in an RFID tag inventory round are provided. A method for adjusting a query command slot-count parameter Q for use by an RFID tag reader includes setting an initial value for Q for a first inventory round, issuing a query command to a population of RFID tags, and monitoring replies from the population of RFID tags. The value of Q is decreased by a first amount if no reply is received, and the value of Q is increased by a second amount different from the first amount if a tag collision reply is received.

Disclosed are a communication system and a synchronization method for enabling synchronization of units included in the communication system in case of a communication line failure. In the communication system according to the present invention, all units are synchronized with the period of an ADSYNC outputted from a master unit when the ADSYNC, in which a data transmission preparation period and a data transmission period make a single cycle, is outputted from the master unit; slave units output a free-run ADSYNC when an ADSYNC is not outputted from the master unit; and, when a plurality of the slave units output free-run ADSYNCs, the slave units are synchronized with any one free-run ADSYNC from among the outputted free-run ADSYNCs.

A communication apparatus includes: a data generating unit that generates write data to be sent to any other communication apparatus at an arbitrary timing; a communication unit that repeatedly sends a read request to the other communication apparatus until the write data is generated and, at the same time, repeatedly receives a read response sent from the other communication apparatus in response to the read request; and a data acquisition unit that acquires read data, which is sent along with the read response by the other communication apparatus, when the read data is generated at an arbitrary timing by the other communication apparatus.

A communication apparatus includes: a data generating unit that generates write data to be sent to any other communication apparatus at an arbitrary timing; a communication unit that repeatedly sends a read request to the other communication apparatus until the write data is generated and, at the same time, repeatedly receives a read response sent from the other communication apparatus in response to the read request; and a data acquisition unit that acquires read data, which is sent along with the read response by the other communication apparatus, when the read data is generated at an arbitrary timing by the other communication apparatus.

Disclosed are methods and apparatus for synchronizing a controller and sensors in a system. A timestamp is provided in a host controller of an interface event on an interface coupled with host controller through detecting a message from a sensor on the interface that identifies the issuance of the interface event caused by the sensor at a first time. In response, the controller issues first and second events on the interface at respective second and third times, while concurrently counting cycles of a clock in the controller after each issuance. The controller also receives a first and second sensor counts representing the internal sensor clock times noted for the first and second events. The controller may then accurately calculate the timestamp of the interface event corresponding to the first time based on both internal controller counts and the sensor counts without needing a timestamp from the sensor directly.

RFID readers and methods for adjusting a query command slot-count parameter Q for use by radio frequency identification (RFID) tag reader in an RFID tag inventory round are provided. A method for adjusting a query command slot-count parameter Q for use by an RFID tag reader includes setting an initial value for Q for a first inventory round, issuing a query command to a population of RFID tags, and monitoring replies from the population of RFID tags. The value of Q is decreased by a first amount if no reply is received, and the value of Q is increased by a second amount different from the first amount if a tag collision reply is received.