Automated and scalable spectrum monitoring will enable regulatory authorities to manage the increasing complexity and volume of wireless services, particularly with the advent of 5G and 5G advanced. This paper explores a method to enhance spectrum management operations through automated and scalable monitoring using multisource measurements. The proposed system enables large-scale monitoring of commercial mobile bands, providing regulators with critical insights into frequency band deployments and service availability. The results illustrate the system’s capability to generate valuable data, aiding in the understanding and management of spectrum deployment and usage, ultimately supporting data-driven spectrum management and sharing.

The satellite is a primary means for providing emergency communication backhaul in disaster areas, where large bandwidth is demanded to support communication services in a wide affected area. Millimeter-wave (mmWave) communication with sufficient spectral resources promises significant enhancement to satellite-terrestrial link capacity. However, the alignment delay and mutual interference caused by directional communications with narrow beams severely limit the capacity of mmWave communication. To this end, we optimize the beamwidth to reduce the impact of beam alignment overhead on capacity. Then, considering the multi-user interference between beams, we propose a transmission scheduling scheme based on beam sharing, namely users with strong mutual interference when served simultaneously by independent beams, share the same beam. A heuristic algorithm is proposed to derive the groups of users sharing beams, and their beamwidth. Simulation results show that the proposed scheme achieves considerable capacity enhancement compared to the one-to-one beam occupation scheme (OB) and fixed beam scheme (FB), thus improving the spectrum efficiency of mmWave satellite-terrestrial communication.

A common technique for improving throughput and increasing spectrum efficiency in wireless networks is the use of header compression. Removing static, implied or redundant protocol fields by synchronizing state information between a sender and receiver reduces per-packet overhead for long lived communication flows. Previous header compression work has focused primarily on single-hop unicast traffic. In this paper we describe a multi-hop multicast header compression (MMHC) scheme applicable to mobile ad-hoc networks. MMHC provides an end-to-end solution where multicast forwarders and receivers are synchronized simultaneously and not hop-by-hop as in previous schemes. Simulation results show that the reductions in per-transmission overhead achieved provide significant gains in both throughput and latency, especially when the average payload size of packets aggregated into the communication flow is small.

Mobile edge computing (MEC) is envisioned as re- expanded cloud compared to fog computing. As making mobile services computing sank to the edge of network further, performance improvement can be got on time aspect. Therefore, MEC is seemed as a potential technology for delay-sensitive applications. Based on that, a reasonable computation offloading strategy would reduce system consumption for MEC further and release its computational capability. In view of resource shortage, especially bandwidth competition problem among Small Cells and edge computational requirements of HetNet, we focus on distributed uplink offloading for MEC in macro-micro coordination scene. It mainly contains two steps. First, based on Lyapunov to solve offloading decision-making problem for users in each Small Cell. Second, complete offloading update order- making of Small Cells in Macro Cell with proposed deviation update decision algorithm (DUDA). Our strategy makes up for the lack of system stability and uplink analysis in existing research. Numerical results demonstrate the effectiveness of our strategy.

Spectrum occupancy prediction is a key enabler of agile and proactive decision-making for dynamic spectrum management. In this paper, state-of-the- art statistical models and machine learning prediction methods are evaluated on real-world occupancy time series measured in the Land Mobile Radio bands. While there is no universally best method for forecasting spectrum usage data, significant accuracy improvements are shown to be achievable by selecting a suitable prediction method for different frequencies. Motivated by this observation, we treat the problem of automating the selection of a suitable prediction method from a candidate pool as a machine learning task. An approach is proposed that recommends the best performing method for new data instances by learning from prior predictions on spectrum data with similar characteristics. The merit of this approach is shown in terms of improving the prediction accuracy compared to baseline selections without the recommender.

This work investigates multicast services, which play a critical role in 5G new radio (NR). In particular, we propose a hybrid unicast/multicast MIMO precoding based on NOMA. Our scheme first categorizes unicast users into NOMA and non‐NOMA types and then utilizes null space and successive interference cancellation to eliminate the signal leakage. To justify the effectiveness and efficiency of our design, we also present simulation results in typical massive MIMO scenarios.

The increasing traffic puts high demands on capacity for the next generation mobile networks. The millimeter-Wave (mmWave) communication system offers new opportunities to meet this requirement due to the tremendous amount of avail- able spectrum. However, the massive non-line-of-sight (NLOS) transmissions and the site constraints in urban environment are severely challenging the conventional way of deploying terrestrial low power nodes (LPNs). To address these problems, we introduce the mmWave aerial base station (mAeBS) in next generation mobile networks, which can be quickly and flexibly deployed to enhance the capacity in data traffic bursting areas. To maximize the enhancing effects, an ergodic capacity analytical model of mAeBS is proposed, considering both user distribution and environment conditions. Then an mAeBS 3D placement method based on the model is given. Simulation results show that the proposed method can achieve considerable capacity enhancement and supplement regional coverage as well.

This paper investigates the application of 5G wireless multicast to the big data system. In particular, we propose a hybrid unicast/multicast transmission scheme using 3D massive multi-input multi-output (MIMO) technique. The proposed scheme employs multicast beamforming in the multicast group and multi-user MIMO (MU-MIMO) linear precoding in the unicast group. It also applies the null space based interference cancellation to eliminate the signal leakage generated by other groups. Simulation results show that the proposed system can significantly improve the system throughput with an antenna array configuration, precoding/beamforming schemes and user grouping strategies.

In this paper, measurements from a spectrum monitoring system are used to investigate sharing scenarios in Land Mobile Radio (LMR) bands. Specifically, channel characteristics which demonstrate sharing opportunities in the time domain in the 450 and 800 MHz LMR bands are presented. Based on the spectrum data, network simulations are conducted to evaluate system performance impacts when the sharing opportunities are exploited to improve spectrum utilization. The results provide improved understanding of appropriate spectrum use models to use for capturing sharing performance in LMR scenarios. It is shown that intelligent spectrum access mechanisms are needed to achieve the best performance trade-offs among utilization efficiency, access delay and airtime.

This paper concentrates on the multicast service in the next generation (5G) communications system, and develops an opportunistic massive MIMO-NOMA scheme. The proposed scheme superimposes the signal of Non-orthogonal Multiple Access (NOMA) users on the multicast signal, and employs successive interference cancellation (SIC) to separate the signal of NOMA users from the multicast signal. This scheme also applies null space based interference cancellation to eliminate the signal leakage generated by other groups. And multi-user MIMO (MU-MIMO) linear precoding is employed in the unicast group. Numerical results revealed that opportunistic massive MIMO-NOMA system significantly satisfies the requirement of high peak spectral efficiency in typical massive MIMO scenarios.

In today's network-centric battlefield, the ad hoc style, self-organizing networks play a more and more important role in the operation of mobile forces that are deployed quickly to meet the tactical demands. However, the unique features of the tactical scenario also pose significant challenges for networking, which makes the existing research results for the general mobile ad hoc networks (MANETs) difficult to be reused directly. In this paper, we focus on the connectivity issue of the mobile tactical networks (MTNs). To better describe the special formation-oriented mobility pattern of MTNs, a more realistic node-following mobility model is used, based on which the neighbor connectivity is obtained from both the geometrical and physical communication point of view for not only 1-D but also 2-D network scenarios. After that, we further evolve our recently proposed decomposition and recursion method to derive the end-to-end connectivity for some formations commonly used in the MTNs. All our analytical results are verified by extensive simulations. We believe that this work is able to shed new lights on the MTNs' performance characteristics, which can be used for guiding the development of the next-generation MTNs.

Mobile ad hoc networks (MANETs) are very useful for communications in areas with very little or no infrastructure. However, that very lack of an authoritative management infrastructure makes it imperative that nodes cooperate by passing traffic fairly and securely. The use of a reputation or trust management system can identify failed, misbehaving or malicious nodes. One aspect of trust management that has been relatively overlooked is the trust distribution service. In this paper, we usea trust model that uses local observations from all nodes in the network to calculate per-node reputation using a trust matrix. We have developed a gossip-based distribution service that reduces network-wide reputation convergence time by prioritising critical trust updates. Simulations show that this distribution service substantially outperforms naïve gossip and provides insight into optimal node density for epidemic-based routing schemes in resource constrained networks.

In this paper, we consider cooperative ad hoc networks and develop an analytical model to study the performance of reliable relaying schemes. In particular, we develop expressions for throughput rate and spectral efficiency for cooperating radios in a fading environment. The numerical results indicate a performance conflict between throughput rate and spectral efficiency, which depends on the underlying relaying schemes, channel quality and number of relays.

In hybrid vehicular ad hoc networks (VANETs), roadside units (RSUs) are more powerful and robust than onboard units (OBUs) equipped on vehicles, which can exchange information and synchronize with other RSUs quickly. Due to the fast mobility of vehicles, wireless links in VANETs are particularly vulnerable to failure. Therefore, it is necessary to provide redundancy in terms of provision multiple link-disjoint paths between source and destination. In addition, VANETs support multiple applications, such as road safety applications and commercial applications, which may require different reliabilities. Accordingly, it is important to discover different number of link-disjoint paths for different applications. In this paper, we propose two notions, virtual equivalent node and differentiated reliable path, and develop an on-demand differentiated reliable routing (DRR) protocol for hybrid VANETs. Extensive simulations show that DRR is beneficial to reduce blocking probability and to maintain lower control overhead while providing differentiated services.

In this paper, the performance of a hybrid medium access protocol in IEEE 802.15.3 has been studied. An analytical model has been developed for the coordination between the contention access period (CAP) and the contention-free channel time allocation period (CTAP). Given the traffic characteristic and the number of contending devices, the piconet coordinator (PNC) determines the duration of the CAP. Based on the successfully received requests and the scheduling scheme, the PNC decides the duration of the CTAP. Extensive simulations are performed to validate our analysis.

In this paper, the performance of adaptive relaying schemes in cooperative diversity (CD) systems equipped with automatic repeat request (ARQ) is studied. Both selection relaying and incremental relaying are considered with a regenerate and forward CD system. The performance metrics of the CD-ARQ system such as efficiency, packet drop rate, average delay and jitter are presented. Numerical results show that selection relaying with a good partner outperforms incremental relaying. In addition, selection relaying performs better than incremental relaying without the ARQ scheme.

In this paper, we investigate efficient data access algorithms in intelligent transportation system (ITS)-based networks with multi-hop wireless links. We introduce a proxy cache (PC) and propose PC-based poll-each-read (P-PER) and PC-based callback (P-CB) data access algorithms to reduce the transmission cost over the bottleneck wireless links. Extensive simulation results are given to demonstrate the performance of P-PER and P-CB. It is shown that P-PER and P-CB can improve the cache hit performance and reduce the transmission cost significantly. A tradeoff between P-PER and P-CB suggests the need to use a hybrid proxy-based approach to attain optimal performance of data access in ITS-based networks with multi-hop wireless links.

We consider downward and upward vertical handovers in integrated wireless LAN and cellular networks, and address wireless profiled TCP premature timeouts due to steep increase of round-trip time and false fast retransmit due to packet reordering. Specifically, we develop a mobile receiver centric loosely coupled cross-layer design, which is easy to implement and deploy, backward compatible with the wireless application protocol version 2 (WAP 2.0) architecture, and robust in the absence of cross-layer information. We propose two proactive schemes which prevent false fast retransmit by equalizing the round-trip delay experienced by all packets and suppress the premature timeouts by carefully inflating retransmission timeout time. We conduct extensive simulations to evaluate the performance in downward and upward vertical handovers. It is demonstrated that the proposed schemes significantly improve the performance in a wide range of network conditions.

In this paper, an agent based WLAN/cellular network integrated service model and relevant authentication scheme is proposed. The service model, or solution, does not require cumbersome peer-to-peer roaming agreements to provide seamless user roaming between WLAN hotspots and cellular networks, which are operated by independent wireless network service providers. Security analysis and overhead evaluation are given to demonstrate that the proposed service model and the supporting schemes are secure and effective.

In this paper, a ticket ID system is proposed for service agent based WLAN/cellular network integrated service architecture. The proposed system accelerates the authentication process for the mobile terminal in the visited network, which effectively compensates the additional cost introduced by the service agent. The design of the ticket ID system also considers the user anonymity feature of the integrated service architecture. The performance evaluation demonstrates the ticket ID system effectively reduces the overall overhead in service agent based integrated service architecture.

Mobile hotspot enabling Internet access services in moving vehicles is an important service for ubiquitous computing. In this paper, we propose an analytical framework for studying the packet loss behavior and throughput in a mobile hotspot with heterogeneous wireless links. We first develop a two-state Markov model for the integrated wireless wide area network (WWAN) and wireless local area network (WLAN). We then derive the expressions that describe the experienced packet loss probability, packet loss burst length, and throughput. Finally, we present simulation results to verify the accuracy of our analysis. It is concluded that adaptive and cross-layer approaches should be deployed to improve the performance of mobile hotspots.

An analytical framework for studying the performance of wireless profiled TCP (WP-TCP) flows over the integrated wireless LAN and cellular networks is proposed. The framework can be used to analyze the short-term performance during vertical handover and long-term performance of WP-TCP for a given set of network and protocol parameters. It captures the WP-TCP behavior under the influence of wireless channel errors, step change in network parameters and excessive packet losses due to vertical handovers. Extensive simulations are conducted to verify the accuracy of the analytical framework. The main findings in this study are: (1) when the network is subjected to hard handovers, increasing the maximum window size improves the efficiency in a high transmission error environment, but degrades the efficiency in a low transmission error environment; (2) increasing the congestion window reduces the chances of premature timeouts during soft upward vertical handover; and (3) depending on duplicate ACK threshold, increasing the congestion window can increase or reduce the chances of false fast retransmit during soft upward vertical handover.

Mobile hotspot enabling Internet access services in moving vehicles is an important service for ubiquitous computing. In this paper, we propose an analytical framework for studying the packet loss rate and throughput in a mobile hotspot with heterogeneous wireless links. We present simulation results to verify the accuracy of our analysis. It is concluded that adaptive and cross-layer approaches should be deployed to improve the performance of mobile hotspots.

In this paper, second order statistical parameters at the maximum ratio combining output of two independent but not necessarily identically distributed Nakagami-m channels are studied. Specifically, generalized expressions of level crossing rate and average fade duration of the combined received envelope are derived. Sample simulation results are presented to verify the correctness of the derived expressions. In addition, numerical results given to demonstrate the behavior of the combined received envelope.

An analytical framework for studying the efficiency and throughput of WAP 2.0 Wireless Profiled TCP (WP-TCP) flows in an heterogeneous wireless environment is proposed. Explicit mathematical expressions that describe the WP-TCP long-run average efficiency and throughput are derived. Simulations are performed to validate the accuracy of the analytical results. It is shown that increasing the maximum window size improves the efficiency and throughput in high transmission error environment, but degrades the efficiency in low transmission error environment.

An analytical model for studying the performance of the delayed acknowledgement (Dly-ACK) mechanism in IEEE 802.15.3 over a fading channel is developed. A three-state Markov channel model is used to approximate both correlated and uncorrelated error processes. Explicit mathematical expressions for the goodput and efficiency of Dly-ACK are derived. It is found that the Dly-ACK mechanism yields higher goodput in a burst error environment than in a random error environment. The goodput tends to increase as the size of the burst increases; however, the amount of increase depends on the underlying delay. Simulations results are given to validate the analytical results.

An analytical framework for studying the latency of wireless application protocol (WAP 2.0) over wireless links for short transfers is developed. In particular, a Markov channel model, which approximates both correlated and independent packet losses, is introduced. For a given wireless link and protocol parameters, an explicit mathematical expression, which represents a reasonable estimate of the minimum WAP 2.0 latency in terms of file transfer time, is derived. Simulation results are given to demonstrate the validity of analytical results. It is shown that for large file sizes (>20 KB), WAP 2.0 is more sensitive to bursty packet losses than random packet losses. It is also shown that the latency of WAP 2.0 can be improved by increasing the size of the initial window in a low rate bursty error environment, but degrades in a high rate bursty error environment.

In this paper, an analytical model for studying the performance of wireless application protocol (WAP) over wireless links is proposed. A Rayleigh fading channel is used to characterize the behavior of wireless channel. Mathematical expressions which represent the performance of WAP as a function of the protocol and the channel parameters are derived. Computer simulation results are presented to validate the analytical results. It is shown that WAP performs better in a bursty error environment than in a random error environment. The goodput of WAP can be increased by increasing the WAP packet group size, but the significance of the improvement depends on the underlying channel condition.

In this paper, an analytical model for studying the performance behavior of wireless application protocol (WAP) over wireless links is proposed. A Rayleigh fading channel model is used to characterize the behavior of the wireless channel. Mathematical expressions that represent the performance of WAP as a function of the protocol and the channel parameters are derived. Computer simulation results are presented to validate the analytical results. It is shown that WAP performs better in a bursty error environment than in a random error environment. The goodput of WAP can be improved by increasing the WAP packet group size, but the significance of the improvement depends on the underlying channel condition.