A wireless terminal and network terminal are provided for implementing a new uplink OFDM protocol. In the new protocol, the wireless terminal has a first transmit chain for generating and transmitting a low rate mode OFDM transmission in a first frequency band of the OFDM band; and a second transmit chain for generating and transmitting a burst-mode transmission in a second frequency band of the OFDM band, the first frequency band being distinct from the second frequency band. An access channel is provided which is overlaid over the low rate mode transmissions of other users.

Dual-mode shared OFDM methods/transmitters, receivers and systems

Techniques for multiplexing and transmitting multiple data streams are described. Transmission of the multiple data streams occurs in “super-frames”. Each super-frame has a predetermined time duration and is further divided into multiple (e.g., four) frames. Each data block for each data stream is outer encoded to generate a corresponding code block. Each code block is partitioned into multiple subblocks, and each data packet in each code block is inner encoded and modulated to generate modulation symbols for the packet. The multiple subblocks for each code block are transmitted in the multiple frames of the same super-frame, one subblock per frame. Each data stream is allocated a number of transmission units in each super-frame and is assigned specific transmission units to achieve efficient packing. A wireless device can select and receive individual data streams.

Multiplexing and transmission of multiple data streams in a wireless multi-carrier communication system

A method and apparatus for allocating subcarriers in an orthogonal frequency division multiple access (OFDMA) system is described. In one embodiment, the method comprises allocating at least one diversity cluster of subcarriers to a first subscriber and allocating at least one coherence cluster to a second subscriber.

Multi-carrier communications with adaptive cluster configuration and switching

Techniques for multiplexing multiple data streams using frequency division multiplexing (FDM) in an OFDM system are described. M disjoint “interlaces” are formed with U usable subbands. Each interlace is a different set of S subbands, where U=M·S. The subbands for each interlace are interlaced with the subbands for each of the other M−1 interlaces. M slots may be defined for each symbol period and assigned slot indices 1 through M. The slot indices may be mapped to interlaces such that (1) frequency diversity is achieved for each slot index and (2) the interlaces used for pilot transmission have varying distances to the interlaces used for each slot index, which improves channel estimation performance. Each data stream may be processed as data packets of a fixed size, and different numbers of slots may be used for each data packet depending on the coding and modulation scheme used for the data packet.

Frequency division multiplexing of multiple data streams in a wireless multi-carrier communication system

Techniques for transmitting overhead information to facilitate efficient reception of individual data streams are described. A base station may transmit multiple data streams on multiple data channels (or MLCs). The MLCs may be transmitted at different times and on different frequency subbands. The time-frequency location of each MLC may change over time. The overhead information indicates the time-frequency location of each MLC and may be sent as “composite” and “embedded” overhead information. The composite overhead information indicates the time-frequency locations of all MLCs and is sent periodically in each super-frame. A wireless device receives the composite overhead information, determines the time-frequency location of each MLC of interest, and receives each MLC at the indicated time-frequency location. The embedded overhead information for each MLC indicates the time-frequency location of that MLC in the next super-frame and is transmitted along with the payload of the MLC in the current super-frame.

Transmission of overhead information for reception of multiple data streams

Performance results from field trial of band hopping OFDM are presented in this paper. Band hopping OFDM utilizes OFDM and slow frequency hopping techniques to provide essential needs for future wireless communications systems. OFDM is currently utilized in digital audio and video broadcasting and DSL. It has been also standardized for wireless LAN applications. A testbed was developed and used in field trials in a suburban area to prove the performance of the band hopping OEDM system. The results indicate that the system is robust against impaired mobile channel conditions. They also show that the system provides superior performance in a multi-path fading environment. Finally, these results support the feasibility of band hopping OFDM techniques for high-speed wireless packet data applications.

http://ieeexplore.ieee.org/iel5/6454/17258/00797146.pdf

Field trial results of a band hopping OFDM system

A precise relative localization system is a crucial necessity for a swarm of Unmanned Aerial Vehicles (UAVs), particularly when collaborating on a task. This paper aims to provide an alternative navigation system to enable a swarm of UAVs to conduct autonomous missions in a Global Positioning System (GPS)-denied environment. To achieve this goal, this paper proposes a relative navigation system using an Extended Kalman Filter (EKF) fusing observations from the on-board Inertial Measurement Unit (IMU) with ranging measurements obtained from the on-board ranging sensors. To ensure secure and high data communication rates, the system employs two waveforms and a low-cost beam-switching phased array. This system thus enables drone operations even in GPS-denied environments. We demonstrate the effectiveness of our approach through simulation experiments involving a swarm of six drones, which includes three fixed and three moving drones in a challenging Blue-Angel scenario. The evaluation of the statistical tests on the results of the simulations shows that this method is efficient. 

Relative navigation of UAV swarm in a GPS-denied environment

We present beam steering module for wireless power transfer system with our ad-hoc mesh network modality. The system comprises of 4×4 butler matrix and 4 1 × 4 patch antenna array operating at 2.45 GHz and provides total azimuthal coverage of 107.3°. This module is then paired with our wireless power transfer system.

Beam Steering for Adhoc Mesh Network Wireless Power Transfer at 2.45 GHz

In this work, we present a method to steer the antenna pattern beam in multiple frequency bands using shared aperture antenna arrays. L and K band frequencies are being used in satellite and surveillance radar systems. Multiple antennas and mechanical rotation is needed to steer the beam towards specific target which makes those systems complex. Here, we proposed a low profile and mechanical rotational system free, shared aperture antenna system for both of the L and K band application. Both of the L and K band antennas are placed side by side on a single substrate while maintaining a low magnitude of crosstalk (<-30 dB). Simulation results confirm that this system is capable of steering the beam across upper hemisphere with <3 dB of loss of gain.

Switched Beam Steering Using Shared Aperture Antenna Array

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Papers

Field trial results of a band hopping OFDM system

Relative navigation of UAV swarm in a GPS-denied environment

Beam Steering for Adhoc Mesh Network Wireless Power Transfer at 2.45 GHz

Switched Beam Steering Using Shared Aperture Antenna Array