Abstract: Spectrum sensing in wireless communications is provided to identify utilized and/or unutilized frequency bands reserved for primary users using a cyclostationary beamforming approach. An adaptive cross self-coherent restoral (ACS) algorithm can be utilized to extract signals of interest (SOI) at unique cycle frequencies related to primary and/or secondary users from an antenna array measurement. Based on the SOI, one or more users of the spectrum can be identified or the spectrum can be regarded as vacant; this can be based on lobe identification in the frequency spectrum of the SOI, in one example. This mechanism is less complex than traditional cyclic spectrum analysis methods. The cyclostationary beamforming based approach is more effective than the energy detection method. Also, the need for quiet periods in spectrum sensing is eliminated when using this mechanism such that signals can be transmitted simultaneously with receiving signals over the antenna array.

Abstract: A transmission protocol is provided for wireless communications in an OFDMA system that uses a rateless code and techniques are provided for dynamically adjusting the subcarrier resources allocated to an OFDMA relay node so that the relay is used at the right time according to the instantaneous channel state information (CSI). As a result, a higher throughput is achieved between source and destination nodes based on a low complexity algorithm for determining when relay assistance is helpful for completing a transmission between the source and destination nodes.

Abstract: Cluster-based cooperative spectrum sensing is provided for cognitive radio systems. For each cluster of cognitive users, a cluster head is determined. Each cluster head collects energies of a reporting channel measured by the cognitive users within the cluster and decides whether a primary user is absent from a given spectrum. A common receiver then aggregates the cluster-level decisions made by the cluster heads, and makes a decision across multiple, or all of, the clusters whether the primary user is absent based on a fusion function of the cluster-level decisions. If the primary (licensed) user is absent, then secondary (unlicensed) users may utilize the spectrum.

Abstract: For cognitive radio systems, the transmit power of a cognitive radio device is controlled so that the cognitive, unlicensed radio device does not interfere with the use of a shared spectrum by a primary, licensed device. Controlling the transmit power includes determining a distance, or a function of the distance, between a primary transmitter of the primary device and the cognitive radio device based on sensing information from a spectrum sensing process. The maximum transmit power of the cognitive radio device is then dynamically controlled based on the distance, or the function of the distance, while considering a worst case scenario of an underlying cognitive radio model, to guarantee a quality of service requirement of the primary device.

Abstract: A full-rate distributed space-time (ST) code design is provided for amplify-and-forward cooperative wireless channels. A signal space diversity technique is employed at the source node and a unique signature vector at each relay node. The distributed space-time (ST) codes can achieve full cooperative diversity and full rate. The achievable diversity gain is M+1, where M is the number of relay nodes. Optimal power allocation can be used to maximize the coding gain under a total power constraint.

Abstract: For cognitive radio systems, the transmit power of a cognitive radio device is controlled so that the cognitive, unlicensed radio device does not interfere with the use of a shared spectrum by a primary, licensed device. Controlling the transmit power includes determining a distance, or a function of the distance, between a primary transmitter of the primary device and the cognitive radio device based on sensing information from a spectrum sensing process. The maximum transmit power of the cognitive radio device is then dynamically controlled based on the distance, or the function of the distance, while considering a worst case scenario of an underlying cognitive radio model, to guarantee a quality of service requirement of the primary device.

Abstract: Cooperative concatenated coding techniques are provided for wireless communications between at least two users and a base station. A network system employing cooperative concatenated coding includes cooperating user devices each configured to encode and transmit at least a potion of a joint message. The joint message includes at least a potion of a first message from a first cooperating user device and at least a potion of a second message from a second cooperating user device. An embodiment includes encoding a first message from a first cooperating user, receiving a second message from a second cooperating user and decoding the second message. The methodology also includes re-encoding at least a potion of the decoded message with at least a potion of the first message to form a combined message, and then transmitting at least a potion of the combined message.

Abstract: Systems and methodologies for employing a multi-user Multiple Input Multiple Output (MIMO) relay protocol with self-interference cancellation in a wireless communication environment are provided herein. Data streams sent between user device(s) and base station(s) can traverse through a relay. Further, a decode and forward protocol can be employed by the relay rather than merely amplifying and forwarding the data streams. Moreover, each user device can listen to and decode data stream(s) sent by other user device(s) to the relay, and these decoded data stream(s) can be utilized for interference cancellation. Further, the user device(s) and the base station(s) can employ self-interference cancellation upon signals received from the relay. According to another example, an adaptive relay power allocation algorithm, which enhances power efficiency, can be leveraged by the relay for transmitting signals to the user device(s) and the base station(s).

Abstract: Spectrum sensing in wireless communications is provided to identify utilized and/or unutilized frequency bands reserved for primary users using a cyclostationary beamforming approach. An adaptive cross self-coherent restoral (ACS) algorithm can be utilized to extract signals of interest (SOI) at unique cycle frequencies related to primary and/or secondary users from an antenna array measurement. Based on the SOI, one or more users of the spectrum can be identified or the spectrum can be regarded as vacant; this can be based on lobe identification in the frequency spectrum of the SOI, in one example. This mechanism is less complex than traditional cyclic spectrum analysis methods. The cyclostationary beamforming based approach is more effective than the energy detection method. Also, the need for quiet periods in spectrum sensing is eliminated when using this mechanism such that signals can be transmitted simultaneously with receiving signals over the antenna array.

Abstract: User cooperation is an emerging transmission framework where users act as relays of each other to provide extra diversity paths for better overall performance. In various embodiments, systems and methods for transmitting data from a basestation to a mobile device in an adaptive communications network including user cooperation are provided. Among various embodiments, relaying is performed according to a time division duplex (TDD) system according to either a downlink-assisted relaying (DAR) which performs a relaying operation in a defined supplemental downlink timeslot or according to an uplink-assisted relaying (UAR) which performs a relaying operation in a defined supplemental uplink timeslot.

Abstract: For cognitive radio systems, the transmit power of a cognitive radio device is controlled so that the cognitive, unlicensed radio device does not interfere with the use of a shared spectrum by a primary, licensed device. Controlling the transmit power includes determining a distance, or a function of the distance, between a primary transmitter of the primary device and the cognitive radio device based on sensing information from a spectrum sensing process. The maximum transmit power of the cognitive radio device is then dynamically controlled based on the distance, or the function of the distance, while considering a worst case scenario of an underlying cognitive radio model, to guarantee a quality of service requirement of the primary device.

Abstract: For cognitive radio systems, the transmit power of a cognitive radio device is controlled so that the cognitive, unlicensed radio device does not interfere with the use of a shared spectrum by a primary, licensed device. Controlling the transmit power includes determining a distance, or a function of the distance, between a primary transmitter of the primary device and the cognitive radio device based on sensing information from a spectrum sensing process. The maximum transmit power of the cognitive radio device is then dynamically controlled based on the distance, or the function of the distance, while considering a worst case scenario of an underlying cognitive radio model, to guarantee a quality of service requirement of the primary device.

Abstract: Spectrum sensing in wireless communications is provided to identify utilized and/or unutilized frequency bands reserved for primary users using a cyclostationary beamforming approach. An adaptive cross self-coherent restoral (ACS) algorithm can be utilized to extract signals of interest (SOI) at unique cycle frequencies related to primary and/or secondary users from an antenna array measurement. Based on the SOI, one or more users of the spectrum can be identified or the spectrum can be regarded as vacant; this can be based on lobe identification in the frequency spectrum of the SOI, in one example. This mechanism is less complex than traditional cyclic spectrum analysis methods. The cyclostationary beamforming based approach is more effective than the energy detection method. Also, the need for quiet periods in spectrum sensing is eliminated when using this mechanism such that signals can be transmitted simultaneously with receiving signals over the antenna array.

Abstract: Spectrum sensing in wireless communications is provided to identify utilized and/or unutilized frequency bands reserved for primary users using a cyclostationary beamforming approach. An adaptive cross self-coherent restoral (ACS) algorithm can be utilized to extract signals of interest (SOI) at unique cycle frequencies related to primary and/or secondary users from an antenna array measurement. Based on the SOI, one or more users of the spectrum can be identified or the spectrum can be regarded as vacant; this can be based on lobe identification in the frequency spectrum of the SOI, in one example. This mechanism is less complex than traditional cyclic spectrum analysis methods. The cyclostationary beamforming based approach is more effective than the energy detection method. Also, the need for quiet periods in spectrum sensing is eliminated when using this mechanism such that signals can be transmitted simultaneously with receiving signals over the antenna array.

Abstract: A transmission protocol is provided for wireless communications in an OFDMA system that uses a rateless code and techniques are provided for dynamically adjusting the subcarrier resources allocated to an OFDMA relay node so that the relay is used at the right time according to the instantaneous channel state information (CSI). As a result, a higher throughput is achieved between source and destination nodes based on a low complexity algorithm for determining when relay assistance is helpful for completing a transmission between the source and destination nodes.

Abstract: Cooperative concatenated coding techniques are provided for wireless communications between at least two users and a base station. A network system employing cooperative concatenated coding includes cooperating user devices each configured to encode and transmit at least a portion of a joint message. The joint message includes at least a portion of a first message from a first cooperating user device and at least a portion of a second message from a second cooperating user device. An embodiment includes encoding a first message from a first cooperating user, receiving a second message from a second cooperating user and decoding the second message. The methodology also includes re-encoding at least a portion of the decoded message with at least a portion of the first message to form a combined message, and then transmitting at least a portion of the combined message.

Abstract: Spectrum sensing in wireless communications is provided to identify utilized and/or unutilized frequency bands reserved for primary users using a cyclostationary beamforming approach. An adaptive cross self-coherent restoral (ACS) algorithm can be utilized to extract signals of interest (SOI) at unique cycle frequencies related to primary and/or secondary users from an antenna array measurement. Based on the SOI, one or more users of the spectrum can be identified or the spectrum can be regarded as vacant; this can be based on lobe identification in the frequency spectrum of the SOI, in one example. This mechanism is less complex than traditional cyclic spectrum analysis methods. The cyclostationary beamforming based approach is more effective than the energy detection method. Also, the need for quiet periods in spectrum sensing is eliminated when using this mechanism such that signals can be transmitted simultaneously with receiving signals over the antenna array.

Abstract: Cooperative concatenated coding techniques are provided for wireless communications between at least two users and a base station. A network system employing cooperative concatenated coding includes cooperating user devices each configured to encode and transmit at least a portion of a joint message. The joint message includes at least a portion of a first message from a first cooperating user device and at least a portion of a second message from a second cooperating user device. An embodiment includes encoding a first message from a first cooperating user, receiving a second message from a second cooperating user and decoding the second message. The methodology also includes re-encoding at least a portion of the decoded message with at least a portion of the first message to form a combined message, and then transmitting at least a portion of the combined message.

Abstract: For cognitive radio systems, the transmit power of a cognitive radio device is controlled so that the cognitive, unlicensed radio device does not interfere with the use of a shared spectrum by a primary, licensed device. Controlling the transmit power includes determining a distance, or a function of the distance, between a primary transmitter of the primary device and the cognitive radio device based on sensing information from a spectrum sensing process. The maximum transmit power of the cognitive radio device is then dynamically controlled based on the distance, or the function of the distance, while considering a worst case scenario of an underlying cognitive radio model, to guarantee a quality of service requirement of the primary device.

Abstract: For cognitive radio systems, the transmit power of a cognitive radio device is controlled so that the cognitive, unlicensed radio device does not interfere with the use of a shared spectrum by a primary, licensed device. Controlling the transmit power includes determining a distance, or a function of the distance, between a primary transmitter of the primary device and the cognitive radio device based on sensing information from a spectrum sensing process. The maximum transmit power of the cognitive radio device is then dynamically controlled based on the distance, or the function of the distance, while considering a worst case scenario of an underlying cognitive radio model, to guarantee a quality of service requirement of the primary device.