Radio access technologies for cellular mobile communications are typically characterized by multiple access schemes, e.g., frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and OFDMA. In the 4th generation (4G) mobile communication systems such as Long-Term Evolution (LTE) (Au et al., Uplink contention based SCMA for 5G radio access. Globecom Workshops (GC Wkshps), 2014. doi:10.1109/GLOCOMW.2014.7063547) and LTE-Advanced (Baracca et al., IEEE Trans. Commun., 2011. doi:10.1109/TCOMM.2011.121410.090252; Barry et al., Digital Communication, Kluwer, Dordrecht, 2004), standardized by the 3rd Generation Partnership Project (3GPP), orthogonal multiple access based on OFDMA or single carrier (SC)-FDMA is adopted. Orthogonal multiple access was a reasonable choice for achieving good system-level throughput performance with simple single-user detection. However, considering the trend in 5G, achieving significant gains in capacity and system throughput performance is a high priority requirement in view of the recent exponential increase in the volume of mobile traffic. In addition the proposed system should be able to support enhanced delay-sensitive high-volume services such as video streaming and cloud computing. Another high-level target of 5G is reduced cost, higher energy efficiency and robustness against emergencies.

Non-Orthogonal Multiple Access (NOMA) for cellular future radio access

The real-time health monitoring system is a promising body area network application to enhance the safety of firefighters when they are working in harsh and dangerous environments. Other than monitoring the physiological status of the firefighters, on-body monitoring networks can be also regarded as a candidate solution of motion detection and classification. In this paper, we consider motion classification with features obtained from the on-body radio frequency (RF) channel. Various relevant RF features have been identified and a support vector machine (SVM) has been implemented to facilitate human motion classification. In particular, we distinguish the most frequently appearing human motions of firefighters including standing, walking, running, lying, crawling, climbing, and running upstairs with an average true classification rate of 88.69 percent. Classification performance has been analyzed from three different perspectives including typical classification results, effects of candidate human motions, and effects of on-body sensor locations. We prove that even a subset of available RF features provides an acceptable classification rate, which may result in less computational cost and easier implementation by using our proposed scheme.

Enlighten Wearable Physiological Monitoring Systems: On-Body RF Characteristics Based Human Motion Classification Using a Support Vector Machine

Time-of-arrival (TOA)-based indoor geolocation suffer from huge distance measurement error caused by multipath and nonline-of-sight (NLOS) conditions. In this paper, we presented a new distance mitigation algorithm based on channel classification and Kalman filter to enhanced TOA performance in multipath and NLOS indoor extreme environment. This algorithm could significantly reduce the ranging error caused by the extreme channel condition in indoor area. We compared the performance of our algorithm with the traditional TOA distance mitigation algorithms, such as Kalman filter, biased Kalman filter, binary hypothesis testing, and ANN, using a commercially available TOA-based geolocation system in typical indoor and underground environments. Results show the performance of our algorithm is much superior to the others.

CC-KF: Enhanced TOA Performance in Multipath and NLOS Indoor Extreme Environment

The optimum energy efficient and spectral efficient designs for type-I automatic-repeat-request (ARQ) systems in Rayleigh flat fading channels are studied in this paper. Three optimum designs are considered: the first scheme maximizes the energy efficiency (EE), or equivalently, minimizes the total energy per information bit without considering the spectral efficiency (SE); the second scheme minimizes a new metric, the energy per information bit normalized by the SE; and the third scheme maximizes the EE under the constraint of a minimum SE. For given physical and link layer parameters, such as hardware power consumption, coding rate, modulation, bit rate, number of overhead bits, and communication distance, the three schemes are optimized with respect to the average transmission energy and the number of information bits per frame. The fundamental EE-SE tradeoff curve is analytically identified via the optimization of the third scheme, and it is shown that the optimum EE is quansiconcave in SE in a type-I ARQ system. The optimum solutions to the first two schemes are special operating points on the EE-SE tradeoff curve. Computer simulation results verify the analytical solutions.

Energy Efficiency and Spectral Efficiency Tradeoff in Type-I ARQ Systems

Currently, most Landsat satellites are deployed in the low earth orbit (LEO) to obtain high-resolution data of the Earth surface and atmosphere. However, the return channels of LEO satellites are unstable and discontinuous intrinsically, resulting from the high orbital velocity, long revisit interval, and limited ranges of ground-based radar receivers. Space-based information networks, in which data can be delivered by the cooperative transmission of relay satellites, can greatly expand the spatial transport connection ranges of LEO satellites. While different types of these relay satellites deployed in orbits of different altitudes represent distinctive performances when they are participating in forwarding. In this paper, we consider the cooperative mechanism of relay satellites deployed in the geosynchronous orbit (GEO) and LEO according to their different transport performances and orbital characteristics. To take full advantage of the transmission resource of different kinds of cooperative relays, we propose a multiple access and bandwidth resource allocation strategy for GEO relay, in which the relay can receive and transmit simultaneously according to channel characteristics of space-based systems. Moreover, a time-slot allocation strategy that is based on the slotted time division multiple access is introduced for the system with LEO relays. Based on the queueing theoretic formulation, the stability of the proposed systems and protocols is analyzed and the maximum stable throughput region is derived as well, which provides the guidance for the design of the system optimal control. Simulation results exhibit multiple factors that affect the stable throughput and verify the theoretical analysis.

Resource Allocation in Space Multiaccess Systems

Future satellite communications (SATCOM) challenges will require cognitive spectrum management and agile waveform adaptation solutions that are not only context-aware and capable of learning and probing for subscriber distributions, quality of services (QoS), mission priorities and traffic patterns, but also agile in waveform adaptation in order to provide active countermeasures for persistent and adaptive radio frequency (RF) interferences. In this paper, we develop a game theory enabled high-level anti-interference strategies. A game theory model of strategic conflicts in SATCOM is designed to guide the high-level antiinterference strategies. Space communication conflicts (interference in congested space environment) were investigated as a two-player, zerosum game in discrete time, where each player discovers the opponent’s exploits according to an impudent random process. The optimal exercise strategies were derived and the value of engaging in space communication conflict was quantified. Problem Statement In the future military satellite communications (MILSATCOM) infrastructure, it is envisioned that satellite communication systems and hybrid spaceterrestrial systems will be the essential components for improved connection capabilities and enhanced defensive control over complex collaborative missions [1]. These wideband space communication networks entail unprecedented complexity and unpredictability of the operating environments as well as extremely high stakes of interference [2]. A game solution [3, 4] and the associated analysis provide high-level insights on SATCOM interference [5]. From our previous work [6], we extend the results to wideband SATCOM. Figure 1 shows an illustrative sketch of the scenario of interest. There are 4 geostationary (GEO) satellites (GEO 1, GEO 2, GEO 3, and GEO 4) for the Blue side (friendly force) and 3 inadvertent interfering satellites (Red side). These interferers may interfere with the space communication among the GEO satellites and Low Earth Orbit (LEO) satellites. Figures 2 and 3 show the interference of GEO 1, LEO 1 and Interferer 1. Figure 1. A Reserch Scenario with GEO SATCOM and Inadvertent Interferers GEO 1

Network survivability oriented Markov games (NSOMG) in wideband satellite communications

This paper discusses the energy- and spectral-efficient transmissions for delay-constrained wireless communication systems utilizing hybrid automatic repeat request (HARQ). Three design metrics are considered: 1) the energy efficiency (EE) measured by the average energy required to successfully deliver one information bit from a source to its destination; 2) the spectral efficiency (SE) defined as the average data rate per unit bandwidth; and 3) the average energy per bit normalized by the SE. Optimum system designs with respect to different metrics are developed by analytically identifying the sequence of transmission energy that should be employed at different retransmissions. The optimum energy distributions are calculated with a new backward sequential calculation method, where the energy at each retransmission round is expressed as a closed-form expression of a wide range of practical system parameters, such as circuit power and channel coding in the physical layer and frame length and protocol overhead in the media access control layer. Reducing the SE-normalized energy per bit yields a balanced tradeoff between EE and SE. Numerical results demonstrate that reducing the SE-normalized energy per bit achieves a 26.7% SE gain over the system that minimizes the average energy per bit; yet, the EE of the two systems is almost identical.

Optimum Energy- and Spectral-Efficient Transmissions for Delay-Constrained Hybrid ARQ Systems

Game theory is a useful method to model interactions between agents with conflicting interests. In this paper, we set up a Game Theoretic Model for Satellite Communications (SATCOM) to solve the interaction between the transmission pair (blue side) and the jammer (red side) to reach a Nash Equilibrium (NE). First, the IFT Game Application Model (iGAM) for SATCOM is formulated to improve the utility of the transmission pair while considering the interference from a jammer. Specifically, in our framework, the frame error rate performance of different modulation and coding schemes is used in the game theoretic solution. Next, the game theoretic analysis shows that the transmission pair can choose the optimal waveform and power given the received power from the jammer. We also describe how the jammer chooses the optimal power given the waveform and power allocation from the transmission pair. Finally, simulations are implemented for the iGAM and the simulation results show the effectiveness of the SATCOM power allocation, waveform selection scheme, and jamming mitigation.

Game theoretic power allocation and waveform selection for satellite communications

The energy efficient design of coded automatic-repeat-request (ARQ) systems is studied in this paper. The optimization aims to minimize the energy required for the successfully delivery of one information bit from a transmitter to a receiver. The design is performed by incorporating a wide range of practical system parameters and metrics, such as hardware power consumption, modulation, channel coding, and frame error rate (FER) in the physical layer, and frame length and protocol overhead in the media access control layer. A new log-domain threshold approximation method is proposed to analytically quantify the impacts of the various system parameters on the FER, and the results are used to facilitate the system design. The optimum transmission energy and frame length that minimize the energy per information bit are identified in closed-form expressions as functions of the various practical system parameters. The analytical and simulation results demonstrate that the total energy consumption in a coded ARQ system can be reduced by increasing the transmission energy during one transmission attempt, and significant energy saving as high as 9.5 dB is achieved with the optimum system.

Gang Wang

Papers

Energy Efficiency and Spectral Efficiency Tradeoff in Type-I ARQ Systems

Network survivability oriented Markov games (NSOMG) in wideband satellite communications

Optimum Energy- and Spectral-Efficient Transmissions for Delay-Constrained Hybrid ARQ Systems

Game theoretic power allocation and waveform selection for satellite communications

Cross-layer design of energy efficient coded ARQ systems