Throughput Analysis for Wireless Networks with Full-Duplex Radios

This paper investigates the throughput for wireless network with full-duplex radios using stochastic geometry. Full-duplex (FD) radios can exchange data simultaneously with each other. On the other hand, the downside of FD transmission is that it will inevitably cause extra interference to the network compared to half-duplex (HD) transmission. In this paper, we focus on a wireless network of nodes with both HD and FD capabilities and derive and optimize the throughput in such a network. Our analytical result shows that if the network is adapting an ALOHA protocol, the maximal throughput is always achieved by scheduling all concurrently transmitting nodes to work in FD mode instead of a mixed FD/HD mode or HD mode regardless of the network configurations. Moreover, the throughput gain of using FD transmission over HD transmission is analytically lower and upper bounded.Comment: 4 figure

Transmission Capacity of Full-Duplex MIMO Ad-Hoc Network with Limited Self-Interference Cancellation

In this paper, we propose a joint transceiver beamforming design to simultaneously mitigate self-interference (SI) and partial inter-node interference for full-duplex multiple-input and multiple-output ad-hoc network, and then derive the transmission capacity upper bound (TC-UB) for the corresponding network. Condition on a specified transceiver antenna's configuration, we allow the SI effect to be cancelled at transmitter side, and offer an additional degree-of-freedom at receiver side for more inter-node interference cancellation. In addition, due to the proposed beamforming design and imperfect SI channel estimation, the conventional method to obtain the TC-UB is not applicable. This motivates us to exploit the dominating interferer region plus Newton-Raphson method to iteratively formulate the TC-UB. The results show that the derived TC-UB is quite close to the actual one especially when the number of receive-antenna is small. Moreover, our proposed beamforming design outperforms the existing beamforming strategies, and FD mode works better than HD mode in low signal-to-noise ratio region.Comment: 7 pages, 4 figures, accepted by Globecom 201

Beamsteering and nullsteering in interference aware wireless networks with point to point beamforming

Title from PDF of title page, viewed on March 19, 2013Thesis advisor: Cory BeardVitaIncludes bibliographic references (p. 45-47)Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2012The concept of beamforming and beamsteering has been gathering immense popularity since the idea's inception. Many in the field of Wireless Communication and in the defense community have tried and succeeded in utilizing the benefits of beamforming and beamsteering with directional antennas. With the increasing popularity of decentralized adhoc networks, it only becomes necessary that the concept of beamsteering be formulated with respect to the network that is being studied. In relation to RF Engineering, the idea of beamsteering has been studied and explored diversely, by proposing beamsteering/ nullsteering algorithms pertaining to Digital Signal Processing. We however, make an attempt to understand beamsteering and nullsteering from the perspective of the physical layer of an Ad hoc network. Hence, it becomes essential that several network parameters like Signal to Interference Ratio, and contention in between individual connections be considered along with the RF parameters like antenna beamwidth, mainlobe and sidelobe gains, Relationship between sidelobes and nulls, Positions of sidelobes and nulls with change in the beamwidth and the number of elements in the directional antenna array. All these different parameters generate a sequence of combinations of results and change the performance of the network accordingly. The crux of this thesis is the antenna pattern model that is consistent with a practical directional antenna pattern, with a mainlobe, several sidelobes and nulls. This antenna pattern is able to derive a network that is much more efficient than its predecessor models that did not use the nulls and sidelobes in their antenna patterns. An algorithm implemented in this thesis shows the vast improvement in the network efficiency, when the different network entities use beamsteering and the alignment of nulls along interfering nodes. It is noticeable that the performance of the network improves by a factor of almost 30 percent due to the implementation of beamsteering as compared to only alignment of nulls along interfering nodes; and by a factor of 37 percent when compared to a model where no Sidelobes and nulls are considered.Introduction -- Ad hoc network with different types of antenna models -- Network model - "sidelobes and nulls" model -- Beamsteering -- Algorithm -- Network simulation -- Results and discussion -- Conclusions and future wor

Simultaneous Transmit and Receive (Star) Antennas for Geo-Satellites and Shared-Antenna Platforms

This thesis presents the analysis, design, and experimental characterization of antenna systems considered for shipborne, airborne, and space platforms. These antennas are innovated to enable Simultaneous Transmit and Receive (STAR) at same time and polarization, either at the same, or duplex frequencies. In airborne and shipborne platforms, developed antenna architectures may enhance the capabilities of modern electronic warfare systems by enabling concurrent electronic attack and electronic support operations. In space, and more precisely at geostationary orbit, designed antennas aim to decrease the complexity of conventional phased array systems, thereby increasing their capabilities and attractiveness. All antennas researched are first designed as a standalone radiator, then as entity of a platform having multiple different antennas.An ultrawideband, lossless cavity-backed Vivaldi antenna array for flush-mounting applications is first investigated. Eigen-mode analysis is used to analyze antenna-cavity interaction and to show that the entire structure may resonate within the band of interest resulting in a significant degradation of antenna performance. A simple approach based on connecting the array’s edge elements in E-plane to the cavity walls is proposed to eliminate the deleterious impact of these cavity resonances. The designed antenna is a 3 × 4 array with 3 elements in E-plane and 4 elements in H-plane, fabricated using stacked all-metal printed circuit board technique. Scan performance of the proposed cavity-backed antenna is investigated in two principal planes and is shown to have similar performance compared to its free-standing counterpart. A simplified version of this single-polarized antenna, when used for broadside only applications is developed. This antenna, excited with a single coaxial feed is shown to have a smaller aperture than the 3 × 4 array. Isolations between two of these antennas when mounted on a compact shared-antenna platform are investigated through computation and experiments.To extend the capability of systems relying on these designed antennas, frequency reuse is enabled through dual-polarized functionality. A dual-polarized, flush mounted, Vivaldi antenna, directly integrated with an all-metal cavity is introduced as an alternative to coax-fed quad-ridge horns. An approach based on shaping the side walls of the cavity is used to eliminate the occurrence of resonances. The proposed dual-polarized resonant-free antenna has two orthogonal 2 × 1 arrays with two elements in the E-plane, one element in the H-plane. It is fed using two 2-way power dividers that can be easily designed to maintain low amplitude and phase imbalances. The antenna is fabricated as a single piece and experimentally shows a monotonic gain increase with low cross-polarization over 4:1 bandwidth.Phased array antennas operating at geostationary orbit are required to scan within Earth’s field of view, without any grating lobe appearance. For dual-polarized applications, this requirement has limited the widespread and attractiveness of these systems at frequencies such as X-band. The narrow 150 MHz guard range between transmit and receive bands, leads to impractical diplexers in conventional dual-polarized systems. This research introduces a dual-polarized subarray architecture for X-band phased array systems which enables high isolation between closely separated TX and RX bands. The proposed approach either eliminates the need for diplexers, or significantly decreases their required complexity

Wideband Monostatic Co-Channel Simultaneous Transmit and Receive (C-STAR) Antenna and Array Systems

Most modern wireless communication systems operate either at different times or frequencies to avoid self-interferences. With these duplexing techniques, more resources are required due to the increased demand for higher data rate. Therefore, alternative solutions not involving more use of the time or frequency spectrum are needed. One of the possible solutions that has been recently gaining increased interest is often referred to as co-channel simultaneous transmit and receive (C-STAR). C-STAR is considered by many as a key enabling technology for the next-generation wireless networks operating in spectrum congested environments. C-STAR allows transmitting (TX) and receiving (RX) at the same time and over the same frequency channel which may result in significant improvements in throughput and spectral efficiency. The chief challenge associated with these C-STAR systems is the required very high TX/RX isolation (110-140 dB) to suppress the self-interference. To obtain the necessary isolation over any bandwidth, a C-STAR transceiver is typically divided into several self-interference cancellation stages. Specifically these include antenna, analog, and digital layers. Clearly, the antenna array layer plays an important role in maximizing the overall system isolation since ~30-50% of the required isolation is achieved with a well-designed C-STAR antenna subsystem, then the overall system becomes feasible. In this Ph.D. thesis, several novel wideband co-polarized circulator and circulator-less monostatic antenna and array designs are presented. Developed theoretical concepts are validated with full-wave simulations and measurements. The monostatic C-STAR apertures utilizing multi-arm spiral antennas are first demonstrated where a set of arms is used for transmitting and the other set for receiving. Then, different novel omnidirectional and broadside C-STAR arrays utilizing closely-spaced spiral, monocone, or discone antennas are introduced. Phase mode orthogonality principle, antenna orientation, and beam-former cancellation are all combined to achieve the desired performance. All proposed C-STAR configurations have theoretically infinite isolation between TX and RX ports. Practically, the achieved isolation is limited by the electrical asymmetries of the used components. Overall, consistent wideband operation, high measured isolation, and good far-field performance are achieved for all proposed C-STAR antenna array sub-systems without taking advantages of any time-, frequency-, polarization-, pattern-, antenna-, and spatial-multiplexing