The specification discloses a method of doing business over the public Internet, particularly, a method which enables access to legacy management tools used by a telecommunications enterprise in the management of the enterprise business to the enterprise customer, to enable the customer to more effectively manage the business conducted by the customer through the enterprise, this access being provided over the public Internet. This method of doing business is accomplished with one or more secure web servers which manage one or more secure client sessions over the Internet, each web server supporting secure communications with the client workstation; a web page backplane application capable of launching one or more management tool applications used by the enterprise. Each of the management tool applications provide a customer interface integrated within said web page which enables interactive Web/Internet based communications with the web servers; each web server, supports communication of messages entered via the integrated customer interface to one or more remote enterprise management tool application servers which interact with the enterprise management tool applications to provide associated management capabilities to the customer.

A communication system for a user having a helmet including earphones and a microphone and including a two-way radio and a microphone-including unit carried by the user and connected to the two-way radio includes a sensor for sensing the presence of the user's head within the helmet. A transmitter associated with the sensor transmits a wireless signal to the microphone-including unit which enables the microphone-including unit to wirelessly receive voice-carrying signals transmitted from the helmet microphone for conductance to the two-way radio and enables the microphone-including unit to wirelessly transmit voice-carrying signals which are received by the microphone-including unit from the two-way radio to the helmet earphones. In addition, helmet-carried componentry permits the user to simultaneously communicate through the two-way radio and a bluetooth enabled cell phone.

A mobile device is provided having a smart card. The smart card is programmed with UICC applications metadata that is provided to the mobile device during a power-up or reset routine. The mobile device uses the UICC applications metadata to generate a user interface that allows a user to launch directly an application on the smart card. Icons for the UICC applications can be displayed together with icons for applications residing on the mobile device. In this way, the user selection of UICC resident applications is facilitated and can be made transparent to the user.

[Problem] To provide a wireless station, a determination apparatus, a wireless communication system, a determination method, and a storage medium which can carry out appropriate interference causing control in a secondary system adaptively to an actual environment with no change in a configuration of a primary system. [Means to solve the problem] A wireless station includes a determination means to determine at least one monitoring station measuring a wireless signal, which is transmitted by the wireless station and which causes interference to another system, out of plural wireless stations of a wireless communication system to which the wireless station belongs.

A wireless communication device is configured for performing uplink transmission power control. The wireless communication device includes a processor and instructions stored in memory. The wireless communication device performs uplink transmission power control for multiple regulated frequency bands or component carriers. The wireless communication device determines a total transmission power for at least one component carrier and allocates transmission power to at least one antenna.

A touch sensitive screen mobile information apparatus having a wireless communication unit for wireless device discovery is herein disclosed. Close proximity wireless device discovery is enabled by wireless searching near distance via radio frequency field for a wireless device, receiving information from the wireless device over the near distance wireless communication, and storing the received information at the information apparatus for future wireless connections. Authentication or pairing of devices may be eliminated due to close proximity of the direct wireless device discovery. After wireless device discovery, the information apparatus and the wireless device may become locked or paired for subsequent wireless communication over any number of wireless communication protocols or standards (e.g., Bluetooth, IEEE 802.11, 2.4GHz) without the need to repeat wireless discovery or pairing. Examples of information apparatus include smart phones, digital camera, laptops, or information pads. Examples of wireless devices include televisions, audio output devices, or printers.

A method and system are provided for controlling uplink transmission power in a wireless communication system. At least one of a plurality of downlink carriers and a plurality of uplink carriers are aggregated, and the plurality of downlink carriers and the plurality of uplink carriers are mapped between a User Equipment (UE) and a network in the wireless communication system. A message relating to uplink carrier transmission power is received at the UE from the network via a downlink carrier. Uplink transmission power of one or more uplink carriers is controlled in accordance with the message and aggregation and mapping of at least one of the downlink carrier and the one or more uplink carriers.

A mobile station includes a measurement unit that measures radio qualities for a serving cell and a candidate switching target cell; a cell switching determination unit that determines whether the radio quality of the serving cell is less than a reference quality corresponded in advance with a predetermined throughput, wherein, when the radio quality of the serving cell is less than the reference quality, the cell switching determination unit determines whether the serving cell is to be switched to the candidate switching target cell by comparing the radio quality of the serving cell with that of the candidate switching target cell; and a radio communication unit that transmits a signal for requesting the switching of the serving cell, and that receives a signal for instructing the switching of the serving cell from a network apparatus.

A wireless communication system is provided that includes a wireless communication device in wireless communication with a base station and mobile stations. The wireless communication device includes first and second transceivers coupled to each other. The first transceiver is coupled to an antenna and is operable to communicate with the base station, which is also in wireless communication with other wireless communication devices. The second transceiver is coupled to another antenna and is in wireless communication with the plurality of mobile stations. The first transceiver receives a first signal from the base station intended for a one of the mobile stations, and in response the second transceiver transmits the first signal to the mobile station. The second transceiver receives a second signal from the mobile station intended for the base station, and in response the first transceiver transmits the second signal to the base station.

The present invention relates to a method and an arrangement for reducing a state transition time from a power saving state for a user equipment (18) in a communication network. The state transition time is reduced by retaining in the user equipment (18) one or more information parameter, such as the radio network temporary identifier for a high speed downlink shared channel (H-RNTI), when performing a state transition to said power saving state so as to enable a time reduction when said user equipment switches back from said power saving state.

A communication terminal that can adjust which section of a one-time pad cipher key is used and achieve cipher communication when there is a possibility that the one-time pad cipher keys are not completely matched between communication terminals. A cipher key transfer device acquires a one-time pad cipher key from a key sharing system, divides the acquired one-time pad cipher key with a predetermined number of bits, and transfers the same to a mobile communication terminal after converting the same into one-time pad cipher key cartridges. Along with the partner's terminal, the mobile communication terminal negotiates which one-time pad cipher key cartridge will be used to perform cipher communication, decides the one-time pad cipher key cartridge to be used, and begins cipher communication.

The invention relates to a method for configuring a mobile device capable of reproducing, for a user, multimedia content previously provided by a remote content server. The invention relates to using a client installed on said electronic device to relay authentication requests between a card, preferably complying with the provisions of the Mobile Commerce Extension standard, and an authentication server that is accessible via an access point.

A system administrator of a wireless LAN 100 manipulates a personal computer PC1 to change a WEP key. The personal computer PC1 authenticates a memory card MC as genuine under management of the system administrator. In the case of the authenticated memory card MC, changed setting information, as well as a previous WEP key before the change of the setting information, is written into the memory card MC. The system administrator then inserts this memory card MC into a memory card slot of a printer PRT1. The printer PRT1 authenticates the memory card MC as genuine under management of the system administrator. In the case of the authenticated memory card MC, the setting information is updated. This arrangement effectively relieves the user's workload in setting wireless communication devices, while ensuring the sufficiently high security.

A method and apparatus for forming and distributing quantum encryption keys. A first quantum signal generated by a number generator in a communicator is transmitted through an aperture in the communicator to a receiving communicator. A second quantum signal is received through the aperture at the communicator from a transmitting communicator. The first quantum signal is isolated from the second quantum signal such that the first quantum signal is transmitted from the communicator in response to the first quantum signal passing through the aperture and such that the second quantum signal is received at a number detector in the communicator in response to the second quantum signal passing through the aperture.

A system that incorporates the subject disclosure may include, for example, instructions which when executed cause a device processor to perform operations comprising sending a service request to a remote management server; receiving from the management server an authentication management function and an encryption key generator for execution by a secure element and an encryption engine for execution by a secure device processor, sending a request to establish a communication session with a remote device; and communicating with the remote device via a channel established using an application server. The secure element and the secure device processor authenticate each other using a mutual authentication keyset. The secure element, the secure device processor and the device processor each have a security level associated therewith; the security level associated with the secure device processor is intermediate between that of the secure element and that of the device processor. Other embodiments are disclosed.

A secret key generation apparatus and method are provided. The secret key generation apparatus includes at least one antenna, amplification/phase controllers, a transceiver, and a random signal controller. The antenna receives a wireless signal from a counterpart terminal that performs wireless communication. The amplification/phase controllers control the amplification gain and phase of the wireless signal that is received via at least one antenna. The transceiver measures the status of a wireless channel using the wireless signal having the controlled amplification gain and phase, determines parameters based on results of the measurement, and generates a secret key based on results of the determination. The random signal controller controls the amplification/phase controllers so that the amplification gain and phase are adjusted whenever the transceiver generates a secret key.

The present disclosure relates to systems and methods for secure communications. In some aspects, one or more values used to generate an encryption key used to encrypt a packet are stored in a header of the packet. The packet is transmitted with the encrypted data portion in a communication. In some aspects, one or more values used to generate an encryption key are received. The encryption key is regenerated using the one or more values.

A method and apparatus for providing additional information included in a video displayed on a display device using visible light communication (VLC). A data packet including video data and additional information for an object included in the video data is received. The video data is extracted from the data packet, and the video data is decoded. The additional information from the data packet is extracted, and the additional information decoded. The decoded video data is output through the display device, and at the same time, the additional information is transmitted for a particular object included in a video based on a VLC protocol using a light emitting device prepared in the display device. The additional information providing apparatus includes an image sensor module, a display module, a visible light receiving module, an additional information manager and a controller.

The present invention provides a content data recording/reproducing device, comprising a communication unit that engages in communication with an external device, a storage unit that stores content data and additional data related to the content data, a content data extraction unit that selectively extracts the content data from the storage unit based upon condition data received at the communication unit from the external device and the additional data stored in the storage unit and a contents list generation unit that generates a contents list based upon the condition data and additional data corresponding to the content data extracted by the content data extraction unit.

A method for calibrating (700) an antenna array comprises a plurality of antenna elements coupled to a plurality of respective receive paths in a wireless communication system. The method comprises, in receive mode, applying a test signal to an individual single receive path (715) of the plurality of receive paths; and feeding back the test signal via a switched coupler network. The method further comprises running a receive calibration measurement routine to determine at least one measurement value used to calibrate the individual signal receive path and waiting for at least one converged measurement value; and extracting (720) the converged measurement value for at least one individual receive path. The steps of applying, running, extracting for a next individual single receive path are repeated until the calibration routine has completed (725). The method further comprises selecting a converged measurement value of at least one individual receive path from a plurality of receive paths (730) to form a reference receiver calibration result (730); normalizing a plurality of at least one measurement values of the plurality of receive paths using the reference receiver calibration result (730); and applying a normalized value to at least one of the plurality of receive paths.

A wireless communication terminal includes a communication status measurement element for measuring communication status data representing a communication status of the self terminal at the time of wireless communications; a reference data storage element for storing respective pieces of preset reference data representing communication statuses of a terminal which can be measured at respective locations at the time of wireless communications, in association with respective pieces of location data identifying the respective locations, and a location specifying element for comparing the communication status data measured by the communication status measurement element with the respective pieces of reference data stored in the reference data storage element, and based on the comparison result, specifying a location corresponding to the location data associated with a particular piece of reference data as a location of the self terminal.

Techniques for determining time of arrivals (TOAs) of signals in a wireless communication network are described. Each cell may transmit (i) synchronization signals on a set of contiguous subcarriers in the center portion of the system bandwidth and (ii) reference signals on different sets of non-contiguous subcarriers distributed across the system bandwidth. A UE may determine TOA for a cell based on multiple signals transmitted on different sets of subcarriers. The UE may perform correlation for a first signal (e.g., a synchronization signal) from the cell to obtain first correlation results for different time offsets. The UE may perform correlation for a second signal (e.g., a reference signal) from the cell to obtain second correlation results for different time offsets. The UE may combine the first and second correlation results and may determine the TOA for the cell based on the combined correlation results.

A powerline communication (PLC) transmission module transmits a signal over a three-line electrical mains supply. The PLC transmission module includes at least two coupling transformers, each transformer coupling the signal to first and second line-pairs of a three-line electrical mains supply, the first and second line-pairs different from one another. Driving circuitry drives a first version of the signal over the first line-pair and a second version of the signal over the second line-pair. Inversion circuitry selectively inverts one version of the signal relative to the other version of the signal, dependent upon an enacted transmission mode. The inversion circuitry may invert neither/both of the versions of the signal so that the signal is transmitted as a differential-mode signal on the line-pairs or invert one of the first and second versions of the signal relative to the other so that the signal is a common-mode signal.

A communication system has a first communication device, and a second communication device that conducts wireless communication the first communication device. The first communication device has a first transmitter that transmits a signal to the second communication device while modulating the signal, and a first transmission controller that controls the first transmitter. The second communication device has a first receiver that receives the signal from the first communication device and demodulates the received signal. The first transmission controller performs control so as to change a modulation method in midstream when a predetermined first signal is modulated and transmitted. The first receiver changes a demodulation method according to the change of the modulation method of the first signal in midstream when the first signal is received and demodulated.

Embodiments include systems and methods of powering a mobile device using a sink device. The method may include detecting a coupling of the mobile device to the sink device and transmitting an acknowledgement in response to a query, the acknowledgement confirming that the sink device has charging capability. Power may be selectively provided in response to the power request. According to some embodiments, the method includes transmitting a query by a communications transmitter to determine if a sink device has charging capability, and deactivating a driver for a power line and transmitting a power request using the communications transmitter in response to receiving an acknowledgement signal from the sink device. The method may further include selectively providing power received from the sink device to a charging circuit of the mobile device. The mobile device may include an HDMI transmitter for communicating through a transmission line to an HDMI sink device.

A wireless media player and a related system and methodology are disclosed. One aspect of the wireless media player system pertains to a virtual connector system, apparatus, and method for the automatic establishment of wireless connectivity with other electronic devices. In one embodiment, the media player device employs the use of integrated Radio Frequency Identification (RFID) technology to exchange communication settings, media capability, and other parameters with an external device that also has integrated RFID technology. The automatic exchange of settings and other information via a proximity-based RFID data exchange allows a media player to quickly establish a secure communication link with another device via a commonly supported wireless protocol such as Ultra Wideband (UWB) or Bluetooth. Another aspect of the media player system pertains to a method of using the captured media capability of the connecting device to customize certain menu options and software parameters in the media player.

An underwater communication device (100) is provided with a voice interface (4), a transceiving unit, a voice quality converting unit and a body (1), etcetera. A bone conduction/throat microphone unit, assembled in the voice interface (4), converts the vocal cord vibrations of a diver to voice signals. The voice quality converting unit converts the voice signals to voice signals based on a clearer voice. A transmitting unit, assembled in the transceiving unit, transmits the converted voice signals to the outside. A receiving unit, assembled in the transceiving unit, receives voice data which is transmitted from the outside. A bone-conduction speaker unit, assembled in the voice interface (4), outputs vibrations corresponding to the voice data received by the receiving unit. Attachment equipment (1, 2, 3) are put on a diver in a state where the bone-conduction speaker unit is in attached to the diver. The receiving unit and the bone-conduction speaker unit are integrally attached to the body (1).

A communication process between two constitutive elements of the network of electricity distribution in a domestic or industrial premise including circuit breakers, electrical modules, switches, electrical plugs and light connection devices. The process including the following steps: assignment by a protocol such as DHCP, BootP or RARP of a first IP address to a first element of the power distribution network, assignment of a second IP address to a second element, and establishment of a communication between the first and second elements of the power distribution network.

A communication module according to the present invention includes a substrate, a laser element and a light receiving element provided on a front surface of the substrate and separating from each other, a transparent resin package collectively sealing the laser element and the light receiving element, and a diffusion unit provided to be opposed to a light emitting surface of the laser element at a prescribed distance for diffusing a laser beam emitted by the laser element, while the distance T between the laser element and the light receiving element satisfies the following formula (1): T≧t1·tan θ+(t1+t2)·tan θ' . . . (1) (in the formula (1), t1 represents the distance between the light emitting surface of the laser element and the diffusion unit, θ represents the maximum angle of emission of the laser element, t2 represents the difference between the height from the front surface of the substrate up to the light emitting surface and the height up to alight receiving surface of the light receiving element, and θ' represents the maximum diffusion angle of the diffusion unit.)

A communication module is provided in which its characteristic of separation between its first and second tuner units is improved. The module is equipped with a circuit board having a first main surface, and a second main surface opposite to the first main surface; a first amplifier arranged on the first main surface, for amplifying a first signal; a first mixer arranged on the first main surface, for converting a signal supplied from the first amplifier to an intermediate-frequency signal; a second amplifier for amplifying a second signal; and a mixer for converting a signal supplied from the second amplifier to an intermediate-frequency signal, both arranged on the second main surface of the circuit board.

A connector-equipped communication module includes a communication module and a connector. The communication module includes a wiring board including antenna-mounted and IC-mounted regions at different positions in a planar view, an antenna element mounted in the antenna-mounted region, a wireless IC and a mounted component mounted in the IC-mounted region, and side terminals in the IC-mounted region and peripheral portions near the IC-mounted region. The connector includes a receiving portion including a placement portion configured to mount the communication module and a wall portion extending around the placement portion, inner wall terminals on an inner side of the wall portion at positions facing the side terminals, and external terminals located outward of the receiving portion and electrically connected to the inner wall terminals. In a state where the communication module is received in the receiving portion, the inner wall and side terminals are fitted so as to contact with each other.

Communication between a retailer and a customer is disclosed. A payment card and a communication identifier addressing a wireless transceiver of a mobile apparatus are registered to an electronic service. The mobile apparatus receives, with the wireless transceiver, a plurality of packets relating to payments with the payment card of a plurality of trades of various commodities between the user and a plurality of various retailers, from the electronic service, extracts from the received plurality of the packets transaction information relating to the payments and supplementary information, and communicates, with a user interface, the extracted transaction information and the supplementary information to the user.

A system and method for transmitting visual data by displaying a synchronization video that includes synchronization code sequences on a first device, capturing the synchronization video using a video camera of a second device, parsing and decoding the synchronization code sequences on the second device, displaying an indication of which of the synchronization code sequences are compatible for visual data transmission on the second device, receiving a selected synchronization code sequence of the synchronization code sequences on the first device, and displaying a data code sequence corresponding to the selected synchronization code sequence on the first device, wherein the data code sequence includes encoded data, and capturing and decoding the data code sequence on the second device.

A semiconductor device prevents recognition failure in mutual recognition between a host and a device compliant with USB Specifications. The semiconductor device includes: an interterminal opening/closing section having a plurality of first conductivity type MOS transistors, the respective sources or drains of which are cascaded, in which the source or drain of a first-stage MOS transistor among the cascaded MOS transistors is used as a first terminal, the source or drain of a final-stage MOS transistor among the cascaded MOS transistors is used as a second terminal, and the respective gates of the cascaded MOS transistors receive a control signal for controlling the opening or short-circuiting between the first and second terminals; and a current bypass section that reduces a current flowing into either one connection node coupling the respective sources or drains of the cascaded MOS transistors.

Various embodiments described herein facilitate multi-lingual communications. The systems and methods of some embodiments enable multi-lingual communications through different modes of communication including, for example, Internet-based chat, e-mail, text-based mobile phone communications, postings to online forums, postings to online social media services, and the like. Certain embodiments implement communication systems and methods that translate text between two or more languages. Users of the systems and methods may be incentivized to submit corrections for inaccurate or erroneous translations, and may receive a reward for these submissions. Systems and methods for assessing the accuracy of translations are described.

A communication apparatus with a multiple-input and multiple-output (MIMO) channel, includes a minimum mean square error (MMSE) detector configured to estimate quadrature amplitude modulation (QAM) symbols based on signals received through the MIMO channel. The apparatus further includes a QAM demodulator configured to demodulate the estimated QAM symbols, and estimate a first posterior probability of each of encoded bits of the estimated QAM symbols, and a first module configured to remove a first prior probability of each of the encoded bits from the first posterior probability to generate soft estimates of the encoded bits. The apparatus further includes a channel decoder configured to decode the encoded bits based on the soft estimates, and generate an improved posterior probability of each of the encoded bits, and a second module configured to generate a second prior probability of each of the encoded bits based on the improved posterior probability.

In general, the present invention provides methods and apparatuses for exploiting the extra degree of freedom provided by the sensing of the CM signal along with the DM signal at the receiver end of a wireline communication system. According to certain aspects, this extra degree of freedom can be used to cancel alien noises at the receiver in both upstream downstream directions. According to further aspects, a CM channel can be potentially used to exploit the diversity created in the CM channel along with the regular DM channel. This acts as the motivation for employing a diversity receiver scheme at the receiver, especially in downstream communications received at a Customer Premises.

A method and system provides for execution of calibration cycles from time to time during normal operation of the communication channel. A calibration cycle includes de-coupling the normal data source from the transmitter and supplying a calibration pattern in its place. The calibration pattern is received from the communication link using the receiver on the second component. A calibrated value of a parameter of the communication channel is determined in response to the received calibration pattern. The steps involved in calibration cycles can be reordered to account for utilization patterns of the communication channel. For bidirectional links, calibration cycles are executed which include the step of storing received calibration patterns on the second component, and retransmitting such calibration patterns back to the first component for use in adjusting parameters of the channel at first component.

Aspects of the subject disclosure may include, for example, a system including a frequency mixer that combines a signal and a carrier wave to form a combined signal, and a transmitter that generates a transmission based on the combined signal. The system can also include a coupling device that emits the transmission as an electromagnetic wave guided by an outer surface of a transmission medium. The electromagnetic wave can propagate longitudinally along the surface of the transmission medium and at least partially around the surface of the transmission medium. Other embodiments are disclosed.

A communication device and a power control method thereof are provided. The power control method, performed by a communication device, includes: determining a power range of a transmit power of an uplink signal; determining a gain switch range based on the power range; when the transmit power of the uplink signal is within the gain switch range, determining a first gain mode for amplifying the uplink signal; and when the transmit power of the uplink signal is out of the gain switch range, determining a second gain mode for amplifying the uplink signal.

In order to transmit a large amount of data in series at a time with a MIMO communication scheme while avoiding deterioration of decoding characteristics due to change over time by a channel matrix, a wireless communication system uses an open-loop type and a closed-loop type of MIMO communication modes in combination and switches to the open-loop MIMO communication mode in response to the information that the amount of data to be transmitted at a time has exceeded a predetermined amount of bits or a predetermined transmission time during data transmission under the closed-loop MIMO communication mode. By discontinuing useless closed-loop MIMO communication and switching to the open-loop MIMO communication mode that is better than Zero-forcing, the decoding characteristics are prevented from simply becoming deteriorated.

In this VSWR measurement circuit, a power measurement unit measures the power level of a reflected signal which is included in a feedback signal which has been extracted at a second CPL which has been deployed at a position connecting to an antenna end via a cable. To this end, the VSWR measurement circuit is provided with a main signal component removal circuit, wherein the main signal which has been extracted from the prestage of a digital pre-distortion circuit, and a signal in which the feedback signal that had been extracted at the second CPL has been converted to a digital signal at an A/D CONV, are provided as inputs, the main signal component included in the feedback signal is removed, and only the reflected signal is extracted so as to be output to the power measurement unit.

A radio communication device capable of randomizing both inter-cell interference and intra-cell interference. In this device, a spreading section (214) primarily spreads a response signal in a ZAC sequence set by a control unit (209). A spreading section (217) secondarily spreads the primarily spread response signal in a block-wise spreading code sequence set by the control unit (209). The control unit (209) controls the cyclic shift amount of the ZAC sequence used for the primary spreading in the spreading section (214) and the block-wise spreading code sequence used for the secondary spreading in the spreading section (217) according to a set hopping pattern. The hopping pattern set by the control unit (209) is made up of two hierarchies. An LB-based hopping pattern different for each cell is defined in the first hierarchy in order to randomize the inter-cell interference. A hopping pattern different for each mobile station is defined in the second hierarchy in order to randomize the intra-cell interference.

Various methods and systems for efficiently performing the blind decoding of downlink signals is described. Several forms of arranging possible CCE combinations are examined and investigated. Based on PDCCH size estimation/information, CCE concatenations that are most likely (of of limited sets) can be arrived at. Tree-based concatenations are also devised using largest CCE ordering to align smaller CCE sizes to similar boundaries. By such ordering, the search space for all possible CCE ordering and sizes can be reduced to an efficient tree. Set mapping between possible lnposelstartCCElnposelend/REs are also described using a first set to secondary and tertiary sets. Various other ordering and sorting schemes are also detailed that enable a blind decode of a PDCCH channel to be efficiently performed.

A method is provided for improving synchronization and information transmission in a communication system, including: generating a signal with a centrally symmetric part s(k) exploitable for synchronization; and sending the signal over a communication channel. The signal is based on a uniquely identifiable sequence c(l) from a set of sequences exploitable for information transmission. The centrally symmetric part s(k) is centrally symmetric in the shape of absolute value thereof. The centrally symmetric part s(k) is of arbitrary length N.

A method and device that interrogates the availability of a called party before placing a communication from the calling party to the called party. A callback may be initiated so that both communications are completed simultaneously. The routing of communication may take place through any one of a number of different networks and at another time of the day, even if the caller does not otherwise have access to those networks.

A duplexer has an antenna terminal, a first terminal, and second terminals and provided with a first filter arranged between the antenna terminal and first terminal and including a parallel resonator for forming a ladder type filter circuit, a second filter arranged between the antenna terminal and the second terminal and having a passband higher than a passband of the first filter, and an electromagnetic coupling element arranged between the parallel resonator of the first filter and a ground part and electromagnetically coupled with the antenna terminal.

A variable filter includes, on a dielectric substrate including ground conductor, first resonator including a transmission line connected to input terminal, second resonator including a transmission line connected to output terminal, and coupling portion including a transmission line having one end connected to the first and second resonators and another end being an open end, or structure having one end connected to the first and second resonators, including a serial connection of a transmission line and a variable capacitor, another end of the variable capacitor connected to the ground conductor, and adjusting means capable of changing electric length, in the first and second resonators and the coupling portion, wherein pass band width can be changed by changing ratio of electric transmission length of the coupling portion to electric transmission lengths of transmission line including the coupling portion, and the first and second resonators.

A filter includes a plurality of primary resonators connected to a serial arm, a plurality of secondary resonators connected to a parallel arm, a primary inductor connected to at least one of the plurality of primary resonators and a secondary inductor connected to at least one of the plurality of secondary resonators. The primary inductor is arranged so as not to be connected to a path between the secondary resonator to which the secondary inductor is connected in parallel and the primary resonator that is connected to the secondary resonator to which the secondary inductor is connected in parallel.

A wireless communication system for agricultural vehicles, in which each vehicle has a global positioning system (GPS), a multi-channel transmitter/receiver module having a limited communication range, and a signal processor connected to the transmitter/receiver module. The transmitter is controlled by the signal processor to transmit on a predetermined communication channel a signal comprising a unique vehicle identifier and a signal indicating the current positional coordinates of the vehicle. The signal processor also analyzes the signals received from other vehicles within the communication range and determines from the identifier and the positional coordinates data when another vehicle is ready to perform a joint operation with the vehicle. Prior to initiation of a joint operation, the communication system is switched to a different communication channel.