Abstract: A cross-layer multi-packet reception media access control and resource allocation technique is provided for wireless networks having receivers with multiple antennas. User devices on the wireless network access the network for data transmission by making a request to send (RTS) request after a random backoff time. In response to a request to send, an access point (or other receiver) determines transmission parameters that optimize the use of the physical layer based at least in part on channel state information. Those transmission parameters are transmitted along with a clear to send (CTS) message from the receiver to an indicated transmitter. Once the CTS message is received, data is transmitted in accordance with transmission parameters.

Abstract: Various embodiments of the disclosed subject matter provide cross layer medium access control systems and methods that dynamically adjusts each node's transmission probability according to physical layer characteristics. Accordingly, when a backoff time counter reduces to zero, each node can selectively transmit according to network population, current CSI, and MPR capability of the system. The disclosed details enable various refinements and modifications according to system design considerations.

Abstract: A system and methodology for channel equalization are provided. According to one aspect, a receiver structure for a MIMO system is provided that employs frequency domain equalization (FDE) with noise prediction (FDE-NP). The FDE-NP structure may include a feedforward linear frequency domain equalizer and a group of time domain noise predictors (NPs), which may operate by predicting a distortion corresponding to a given linearly equalized data stream based on previous distortions of all linearly equalized data streams.

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: System and methodologies are provided herein for multiuser scheduling in a multiple-input multiple-output (MIMO) communication system. Various aspects described herein facilitate full feedback scheduling, wherein multiuser scheduling is performed based on an antenna selection and signal quality feedback, such as signal-to-interference-plus-noise ratio (SINR) feedback, from respective users. Based on information received from respective users, independent information streams can be transmitted from respective transmit antennas to respective users with the highest signal quality. Receive antenna selection can also be employed to allow respective users to select a single receive antenna on which information is to be received. Additional aspects described herein facilitate quantized feedback scheduling, wherein scheduling is performed based on signal quality feedback that is quantized into a finite number of bits by respective users.

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: 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: High-rate bit transmitted data is serial to parallel converted into low-rate bit streams in a similar fashion to multicarrier or multitone modulation. However, in contrast to the multicarrier method, each low-rate bit stream is modulated using direct-sequence spread-spectrum. By selecting the processing gain properly the total required bandwidth will be of the same order as the original high-rate data stream, thereby gaining the inherent benefit of multipath rejection without expanding the bandwidth of the original high-rate stream.