Joe Lee

Emerging satellite communication links of incompatible polarization via wavefront multiplexing techniques

There are many Ku band linearly polarized (LP) space assets covering different service areas for fixed satellite services (FSS). On the other hand, circularly polarized (CP) terminals are more economical in manufacturing and installations as comparing to compatible LP terminals. The presented techniques will enable satellite operators to cost-effectively service Ku band VSAT users, either fixed or mobile, via LP space assets in Ku band. A method for grouping multiple LP satellite transponders through Wave-Front (WF) Multiplexing (muxing) techniques is presented. Grouped LP transponders become accessible efficiently by CP ground terminals and vice versa. This method consists of a polarization converting processor in a ground hub with our modifications of ground user equipment and satellite assets. In addition, applications of WF muxing techniques to satellite communications offer many advantages, including improved flexibility and utility efficiency of existing space assets. Proposed methods enable service providers to service CP VSAT terminals equally well either through LP or via CP space assets, and teleport operators with greater flexibility in how they manage their assets.

Incompatible Polarization Wavefront Multiplexing: A New System Perspective

The principle of frequency reuse by orthogonal polarization has long been of critical importance in satellite communications. The same portion of allocated bandwidth can be used for two signals broadcast in opposite polarizations. It has been common practice that the terminals and transponders use compatible polarization for communications. In this paper, we present a new perspective on satellite communications with focus on incompatible polarization. We observe that circularly polarized (CP) terminals are becoming more economical in manufacturing and installations as comparing to compatible linearly polarized (LP) terminals. It shall be valuable to enable satellite operators to cost-effectively service Ku band VSAT users (terminals or hubs), either fixed or mobile, via LP space assets in Ku band. Toward this end, we have developed a method that exploits multiple LP satellite transponders through Wave-Front (WF) Multiplexing (muxing) techniques. Multiple LP transponders become accessible efficiently by CP ground terminals and vice versa. The applications of WF muxing techniques to satellite communications offer many advantages, including improved flexibility and utility efficiency of existing space assets. Proposed methods enable service providers to service CP VSAT regardless the polarization formats of space assets, allowing teleport operators to manage their assets with greater flexibility.

Interoperability of Incompatible Polarization Satellite Assets: A Wavefront Multiplexing Approach

We propose a Wave front Multiplexing Approach to connecting satellite assets using incompatible polarization. Hence, two families of satellite assets using either linearly polarized (LP) antennas or circularly polarized (CP) antennas can be made interoperable. As a motivating example, satellite operators can cost-effectively service Ku-band CP VSAT users enabled by Wave front Multiplexing via LP transponders. Central to our proposed approach is a processing unit that exploits incompatible polarization in a ground hub. In addition, resource (e.g. Power) allocation via Wave front Multiplexing can be performed to meet communication requirements. Service providers that operate Wave front Multiplexing may manage either LP or CP space assets equally well to service CP VSAT terminals.

Smart satellites in Smart Grids

Satellite services for users in smart grids may be studied from the perspectives of market and technology. Economic variation has led to the transition of satellite communications services among different spectrum segments. The short-term demand for capacity drives the potentially increased use of satellites operating in high frequency band. However, satellite transponders at moderate frequency band may enjoy lower cost as compared with its counterpart in higher frequency band. There have been many satellites covering different service areas, which may constitute a considerable amount of revenue in satellite services. On the other hand, some satellite communication terminals may be manufactured and installed in order to use some waveforms. Satellite communications systems shall enable satellite operators to service users that employ some waveforms via satellite transponders. Hence the transponders may become accessible for the ground terminals. The operators of satellite communications systems may use a given satellite transponder to service users employing some waveforms within the spectrum of interest.

Multiple orthogonal beams with multi-user and frequency reuse via active scattering devices

This paper explores a multi user wireless deterministic channel in the presence of active scattering devices, or active scatters. Optimization of weighting vectors is employed on the transmitter side to form multiple orthogonal beams that feature frequency reuse at the same time. We focus on the possibility of forming two orthogonal beams. With the use of MATLAB and CVX, the solvability of optimal weighting vectors can be determined. Each orthogonal beam is dedicated to one specific receive antenna element with at least 20 dBm suppression of the beam pattern at other receive antenna elements. The peak of one beam is aligned with nulls (i.e. -20 dBm) of other beams. We simulate the system by adding QPSK modulation and determine the performance of the proposed system that transmits signals via multiple orthogonal beams.

Satellite communications service provision via incompatible polarization diversity and orthogonal beams

Satellite communication systems rely on frequency reuse to maximize spectrum efficiency over a coverage in response to the increasing demand for capacity. Multibeam terminals may enable high data traffic via multiple satellites to send various IP data to different destinations concurrently via frequency reuse. Presented are techniques exploiting incompatible polarization diversity and orthogonal beams (OB) for satellite communications. One such technology is Wavefront (WF) Multiplexing/Demultiplexing (Muxing / Demuxing) that enables satellite communications assets to service subscribers with incompatible polarization formats. A satellite transponder that employs WF Muxing/Demuxing may supply service provision to more ground terminals, regardless the polarization format, in its field of view. On the other hand, ground terminals equipped with multi-beam antennas form beams to access multiple intended transponders on various satellites in different orbital slots with high isolations on a same frequency via orthogonal beam (OB) techniques. Our solution offers the satellite communication market multifold advantages: lower cost, higher efficiency and considerable flexibility, among others.

A new perspective on satellite communications via incompatible signal polarization features and wavefront multiplexing techniques

In this paper, we propose a technical solution to a realistic yet unanswered market question for the satellite communications industry: how can Ku-band satellites be designed to service increasing number of VSAT (very-small-aperture-terminal) users in FSS (fixed satellite service) market with lower cost? We first notice that economic considerations have dictated the transition of satellite communications services among different frequency bands. The short-term demand for capacity drives the potentially increased use of Ka-band satellites. However, Ku-band satellite transponder enjoys lower cost as compared with its Ka-band counterpart. There are many Ku-band linearly polarized (LP) satellites covering different service areas for fixed satellite services (FSS), which constitute the majority source of revenue in satellite services. On the other hand, circularly polarized (CP) terminals, some of which have been serviced by Ka-band satellites, are more economical in manufacturing and installations as compared with compatible LP terminals. The major bottleneck is the concurrent use of CP and LP formats in conventional communication systems. In this paper we present a class of WaveFront (WF) Multiplexing (muxing) techniques that revitalize CP-to-LP and LP-to-CP links and enable satellite operators to cost-effectively service VSAT users employing CP waveforms, either fixed or mobile, via Ku band LP transponders. Coherent power allocation becomes feasible for satellite communications between assets using incompatible polarization and WF muxing. WF muxing makes it operational for CP VSAT terminals to access LP or CP space assets equally well. WF muxing also allows satellite transponders, either in LP or CP format, to concurrently service both LP user and CP user communities equally well for spectrum efficiency.

Transmitter beam-forming techniques for indoor millimeter wave communication

This paper explains a new beam-forming technique implemented in a deterministic multiple-input multiple output (MIMO) channel model. The path loss is calculated between the transmitter and the receiver antenna elements in line of sight (LOS) path. Assume that channel state information (CSI) is known as the deterministic values at the transmitter, the composite transfer function (CTF) along with the CSI (i.e. a path loss matrix), generates orthogonal beams. The same frequency is reused for multiple orthogonal beams at the same time slot. Our beam-forming technique controls the radiated power at the transmitter in such a way that the power at a particular receiving antenna element is 0dB and it is suppressed to −40dB or lesser at other receiving elements. The performance of our proposed beam-forming technique is analyzed by transmitting the QPSK modulated signal through the orthogonal beams from the transmitter and their bit error rate (BER) curve is analyzed at the receiver. The complete simulation of our system in this paper operates at millimeter wave frequency of 60GHz.

Beamforming solvability in 3D space using active scattering devices

Most multiple-input multiple-output (MIMO) wireless communication systems currently rely on probabilistic or stochastic channel models. However, in this paper we will describe a deterministic approach to the channel model in order to beam form an indoor signal from multiple transmitters to a single receiver in a group with the non-receiving elements effectively receiving noise only. The use of Composited Transfer Functions (CTF) with the channel state information (CSI) in a deterministic approach allows for precise multipath path loss calculations that permit for the generation of orthogonal beams at specific receiving elements. Frequency reuse is possible such that only the specified device is receiving signals and allows for multiple users to transmit and receive data on a single frequency. We show that through the additional use of active gain scattering devices, optimizer solvability increases and allows for larger areas and more diverse geometries of transmit and receiving elements. The capabilities and effectiveness of our deterministic beamforming approach with and without the use of active scatterers are discussed in this paper.

Enabling CP terminals for accessing LP satellite transponders via wavefront multiplexing techniques

Satellite links supported by circularly polarized (CP) antennas and linearly polarized (LP) antennas respectively have long been conceived as two incompatible assets. Via Wavefront Multiplexing techniques, we show that the CP and LP satellite assets can be mutually assistive. There are some markets that have been populated with many LP satellites and CP terminals. The presented techniques enable satellite operators to cost-effectively service Ku-band VSAT users, either in fixed satellite service (FSS) or mobile satellite service (MSS) markets, via LP space assets in Ku band. Central to our subject are the Wavefront Multiplexing (WF muxing) techniques. Multiple LP transponders become accessible efficiently by CP ground terminals, and vice versa, without modifications of ground user equipment and satellite assets. In addition, applications of WF muxing techniques offer the following extended features to the transponders: (1) coherent power combining of output powers, and (2) dynamic output power allocations. Proposed methods not only enable VSAT terminals to access CP or LP space assets equally well, but also allow teleport operators to manage their assets with greater flexibility.