Abstract: A mobile station (104) operates in a region where an incumbent operator (110) is transmitting. The secondary station transmits at a frequency similar to that of the incumbent operator's signal. The incumbent operator transmits using a particular polarization (113). To reduce interference, the secondary station selects one of a plurality of antennas of the secondary station which has a low matching polarization with that of the incumbent signal.

Abstract: The radio frequency (RF) environment is scanned and analyzed prior to entering a building or otherwise non-ideal propagation path environment. Upon entering the building or non-ideal propagation path environment, the mobile unit will scan the RF environment from within the building. An attenuation factor is determined for various frequencies. A channel then chosen to operate on in the cognitive system based on the attenuations of the various frequencies.

Abstract: During operation of a secondary communication system 100, a device will perform spectrum sensing of certain channels (either by itself or as part of a group of nodes 104). When activity is found on a channel from a primary user, other devices will be notified that the channel is not available for use. The device may then modify its spectrum sensing to assist another device (or group of devices) that have not yet found activity on a different set of channels. By assigning additional channels to devices with extra capacity, the overall spectrum-sensing efficiency and performance of the communication system 100 is raised.

Abstract: A source device (110) receives a carrier signal and continuously monitors the carrier signal for a first predetermined condition and a second predetermined condition. The source device (110) transmits data if the first predetermined condition is satisfied. The source device (110) ceases transmission of data if the first predetermined condition subsequently is not satisfied or if a second predetermined condition is satisfied.

Abstract: A technique for a secondary communication system to utilize spectrum designated to another (or primary) communication system is provided. By ranking a plurality of secondary base stations based on base station transmit power, calculated required transmit power and path loss, a set of criteria is developed for selecting a highest ranked secondary base station for operation within a primary's spectrum. The ranking may be adapted based on mobility of the secondary's subscriber; and as such the secondary system communicates within the primary's spectrum using the adaptively ranked base stations. Channel selection may also be ranked. The technique and apparatus allows a cognitive radio (CR) network to operate within an incumbent network's spectrum.

Abstract: A communications system and method for exchanging spectrum usage information through a drop box (100) includes one or more central stations (101) that defines a region of operation. A central drop box (102) is associated with the central station (101) for providing a database of spectrum usage information. Stations (103, 105, 107) using the communications system may submit information regarding spectrum usage to the central drop box (102) that affects the region of operation (109, 115) for providing the most efficient and non-interfering uses of the frequency spectrum.

Abstract: A cognitive radio (CR) device (208 and/or 218) avoids interference with an incumbent (207) receiver by determining maximum allowed transmit power levels of the CR device based on estimates of the incumbent signal level and transmit splatter levels of the CR device. The CR device (208 and/or 218) avoids interference with the incumbent receiver while transmitting with maximum transmit power levels.

Abstract: A system and method for minimizing inter-communications system mobile-to-mobile station interference includes a plurality of base stations (BS A and BS B) and a plurality of mobile stations (MS A and MS B) each communicating with a base station using a first mode of communication. A first mobile station (MS A) sends a message using a second mode of communication upon detecting interference with another mobile station (MS B) to determine the source of the interference. Once determined, the first mobile station (MS A) communicates with its base station (BS A) which, in turn, communicates with the second mobile station's base station (BS B) using a back haul network. The second mobile station's base station (BS B) may then instruct the second mobile station (MS B) to alter its transmission characteristics based upon instructions from the second base station (BS B) in order to reduce interference and improve overall communications quality.

Abstract: A DTV signal detector detects DTV signals received by a receiver on a selected DTV channel in a Digital Television System. The DTV detector includes a first DTV signal detector that detects a first characteristic of the received DTV signals, and a second DTV signal detector that detects at least a second characteristic of the received DTV signals. A controller responds to the first DTV signal detector and the second DTV signal detector to control a selection of the DTV channel being selected by the receiver. The receiver can be synthesized to select from more than one DTV channel.

Abstract: A means for determining a channel for communication in a wireless communication system is provided. A method includes receiving one or more sub-frames of a beacon signal on a beaconing channel until a legitimacy condition of the beacon signal is met. The beacon signal is transmitted by a beaconing device. The method further includes determining a suitability of the channel for communication in the wireless communication system based on the legitimacy condition.

Abstract: During operation of a secondary communication system, cells (106) are formed by a plurality of localized nodes (104) to alert other nodes within the cell of frequencies which must be protected or otherwise avoided. All nodes within the cell monitor a differing subset of all frequencies available, and share information with respect to acceptable and protected frequencies with each other via low-power, short-range communication. Each node then forms a list of available channels for communication, and chooses a single node to report this information back to controller.

Abstract: A technique for dynamic spectrum sharing includes identifying (705) a plurality of radio nodes (115, 120), measuring (710) a local signal value (SV) at each radio node (110, 200), and determining (715) a transmit decision. Each radio node can measure a local signal value (SV) of a protected transmission and the radio nodes are within a uniform SV region of the protected transmission. The transmit decision is determined for at least one of the plurality of radio nodes based on the SV of each radio node in the plurality of radio nodes and at least one threshold value that is related to statistical characteristics of the protected transmission at an interference boundary (105) of the protected transmission and a desired probability of non-interference with the protected transmission at the interference boundary.

Abstract: During operation of a secondary communication system 100, a device will perform spectrum sensing of certain channels (either by itself or as part of a group of nodes 104). When activity is found on a channel from a primary user, other devices will be notified that the channel is not available for use. The device may then modify its spectrum sensing to assist another device (or group of devices) that have not yet found activity on a different set of channels. By assigning additional channels to devices with extra capacity, the overall spectrum-sensing efficiency and performance of the communication system 100 is raised.

Abstract: A method and apparatus for allocation of shared spectrum in a wireless communication system uses a radio frequency (RF) beacon signal that is transmitted between access points of the wireless communication system. The information content of the RF beacon signal includes an identifier of the access point that generated the signal, identifiers of clients of that access point; and identifiers of the communication channels assigned to those clients. The client identifier may include at least part of an Internet Protocol (IP) address of the client. Additionally the beacon signal may contain client attributes to enable negotiation of the sharing of available communication channels between access points and clients.

Abstract: A node of a wireless mesh network assigns a radio frequency (RF) channel for operation by sensing an interference level in a number of RF channels, determining which RF channels are available for use and selecting the available RF channel having the best performance. The node then attempts to communicate with neighboring nodes of the wireless mesh network using the selected RF channel. If communication with a sufficient number of nodes is not achieved, the node selects an available RF channel having the next best performance, and attempts to communicate with neighboring nodes using the selected RF channel. The process is repeated until the node can communicate with a sufficient number of nodes. The selected RF channel is then assigned for node operation.

Abstract: During operation of a secondary communication system, cells (106) are formed by a plurality of localized nodes (104) to alert other nodes within the cell of frequencies which must be protected or otherwise avoided. All nodes within the cell monitor a differing subset of all frequencies available, and share information with respect to acceptable and protected frequencies with each other via low-power, short-range communication. Each node then forms a list of available channels for communication, and chooses a single node to report this information back to controller.

Abstract: The radio frequency (RF) environment is scanned and analyzed prior to entering a building or otherwise non-ideal propagation path environment. Upon entering the building or non-ideal propagation path environment, the mobile unit will scan the RF environment from within the building. An attenuation factor is determined for various frequencies. A channel then chosen to operate on in the cognitive system based on the attenuations of the various frequencies.

Abstract: The present invention provides a multi-band, multi-mode RFID tag that uses a single antenna structure and integrated circuit to provide asset location information at any stage of a supply chain. The unified tag design operates at multiple frequencies (or bands) using the antenna structure, for example, 125 kHz, 13.56 MHz, 915 MHz, and 2.45 GHz, and preferably operates electrostatically (at lower frequencies) and electromagnetically (ay higher frequencies). An on-chip frequency monitor in the integrated circuit automatically determines which frequency is present and derives a local clock for the tag's integrated circuit, which can vary in accordance with the frequency or which can be constant. Alternatively, a phase locked loop circuit can be used to derive a local clock signal modulated into the interrogation signal. On-chip matching and power extraction circuits derive power for the tag from the interrogation signal, which is preferably passive.

Abstract: The presence of the non-television transmission within a channel is used to indicate that secondary non-licensed usage of the channel is permitted. Specifically, if secondary users incorporate the means to identify the unique modulation signature of the secondary user, decoding of a beacon signal may not be necessary. With the above in mind, a radio will be prevented from transmitting within a frequency band when no transmission within the licensed spectrum is currently taking place; the licensee is currently transmitting on the spectrum (e.g., television transmissions are taking place utilizing the spectrum, or the radio cannot sense the presence of a data channel (beacon).

Abstract: A receiver receives elements of a signal sequence. A state generator generates a sequence of addresses to translate between a pseudonoise sequence and a Walsh sequence. A storage medium, coupled to the receiver and the state generator, stores each element of the signal sequence at a given address according to the sequence of addresses.