Abstract: A communication apparatus determines whether another communication apparatus participating in a network established in accordance with a first communication standard is also compatible with a second communication standard. The communication apparatus detects leaving of the network by another communication apparatus incompatible with the second communication standard. The communication apparatus establishes a network that adheres to the second communication standard, depending on the detection result.

Abstract: In an ad hoc mode based on IEEE802.11 standard, when a wireless terminal performs a power save operation to create a network, and a network identifier identical to that of the network to be created is present, the wireless terminal does not join the network. When the wireless terminal is to join the network, and the network identifier identical to that of the network which the wireless terminal is to join is not present, the wireless terminal does not join any network. In this method, reliable connectivity can be obtained in the ad hoc mode which is not defined in the IEEE802.11 standard in detail.

Abstract: In an ad hoc mode based on IEEE802.11 standard, when a wireless terminal performs a power save operation to create a network, and a network identifier identical to that of the network to be created is present, the wireless terminal does not join the network. When the wireless terminal is to join the network, and the network identifier identical to that of the network which the wireless terminal is to join is not present, the wireless terminal does not join any network. In this method, reliable connectivity can be obtained in the ad hoc mode which is not defined in the IEEE802.11 standard in detail.

Abstract: To reduce the processing load and maintain higher security in the communications, a communication apparatus includes a network surveying unit configured to determine at least one of (1) an architecture of a network comprising the communication apparatus, and (2) the number of apparatuses on the network; and an alteration detecting unit configured to perform alteration detection processing on data packets received by the communication apparatus, the processing being based on the determination by the network surveying unit.

Abstract: In a communication apparatus on a network where communication apparatuses perform direct communication with each other, a network management apparatus for managing the network based on message information transmitted and received on the network is determined. When the communication apparatus itself is determined as the network management apparatus, the apparatus collects information indicating device capabilities from other communication apparatuses. On the other hand, the communication apparatus receives information indicating device capabilities from another communication apparatus when the other communication apparatus is determined as the network management apparatus.

Abstract: A communication device is provided having wireless capabilities configured to communicate in a first communication mode via an access point and in a second communication mode directly between other communication devices without utilizing an access point. The communication device includes a detecting unit configured to detect the existence of an available wireless network; a receiving unit configured to receive a request from another communication device for transferring communication parameters in the second communication mode; and a transmitting unit configured to transmit communication parameters relating to the available wireless network to the other communication device in response to the request.

Abstract: In a communication apparatus on a network where communication apparatuses perform direct communication with other apparatuses, a providing apparatus that provides communication parameters, and a reception apparatus that receives the communication parameters are determined based on information indicating the capabilities of communication apparatuses existing on the network, and a transfer direction of the communication parameters is notified to the providing apparatus and the reception apparatus thereby determined.

Abstract: A device capability attribute regarding a setting on communication parameters, and provision attribute information indicative of whether or not a communication terminal is in a state that it can provide communication parameters to another communication terminal are stored in advance. The communication terminal, where the device capability attribute has at least a provision capability of the communication parameters, is selected as a provision device. In a case where there are plural communication terminals where the device capability attribute has a communication parameter provision capability, a communication terminal where the device capability attribute has the communication parameter provision capability only is preferentially selected.

Abstract: When it is determined that a power mode is a power save mode, and that a MAC address in a received beacon matches the MAC address of a wireless communication apparatus which newly joins a wireless network, the power mode of all the communication apparatuses which have joined the wireless network is switched from the power save mode to a normal power mode.

Abstract: In an ad hoc mode based on IEEE802.11 standard, when a wireless terminal performs a power save operation to create a network, and a network identifier identical to that of the network to be created is present, the wireless terminal does not join the network. When the wireless terminal is to join the network, and the network identifier identical to that of the network which the wireless terminal is to join is not present, the wireless terminal does not join any network. In this method, reliable connectivity can be obtained in the ad hoc mode which is not defined in the IEEE802.11 standard in detail.

Abstract: In a communication system including plural communication apparatuses that communicate each other using a single communication path, the state of the communication path is detected for communication. If the communication path is busy, a first control method is performed for controlling access to the communication path using a back off time selected at random. A second control method secures the communication path by transmitting and receiving the predetermined signal at transmission of a signal so as to control access to the communication path. In accordance with the kind of the signal to be transmitted, the first or the second control method is selected for communication. Thus, plural communication apparatuses can perform efficient communication.

Abstract: A bidirectional optical space transmission system is made up of a pair of optical transmission apparatus. Each optical transmission apparatus comprises a signal generating circuit for generating a pilot signal, a multiplexing section for multiplexing the pilot signal and a main signal to be transmitted, an electrooptic converter section for emitting an optical signal on the basis of the signal produced by the multiplexing process, a light receiving element for receiving an optical signal transmitted from the partner optical transmission apparatus and detecting a pilot signal contained therein, and a demodulation circuit for demodulating the pilot signal detected by the light receiving element. Pilot signals multiplexed with main signals to be transmitted through the bidirectional optical transmission system are subjected to spreading modulation and demodulated for spreading by the demodulation circuit.

Abstract: A receiving apparatus includes a base-band conversion circuit, a synchronizing circuit/code generator and a demodulator. The base-band conversion circuit converts a received signal into a base-band signal. The synchronizing circuit/code generator detects a spread code included in the received signal to generate a plurality of spread codes in synchronization with the spread code included in the received signal. The demodulator uses the plurality of spread codes supplied by the synchronizing circuit/code generator to demodulate the base-band signal.

Abstract: In a communication system including plural communication apparatuses that communicate each other using a single communication path, the state of the communication path is detected for communication. If the communication path is busy, a first control method is performed for controlling access to the communication path using a back off time selected at random. A second control method secures the communication path by transmitting and receiving the predetermined signal at transmission of a signal so as to control access to the communication path. In accordance with the kind of the signal to be transmitted, the first or the second control method is selected for communication. Thus, plural communication apparatuses can perform efficient communication.

Abstract: A receiving apparatus includes a base-band conversion circuit, a synchronizing circuit/code generator and a demodulator. The base-band conversion circuit converts a received signal into a base-band signal. The synchronizing circuit/code generator detects a spread code included in the received signal to generate a plurality of spread codes in synchronization with the spread code included in the received signal. The demodulator uses the plurality of spread codes supplied by the synchronizing circuit/code generator to demodulate the base-band signal.