Due to severe signal pathloss in millimeter wave (mmWave) band, beamforming enabled directional transmission is critical to overcome the attenuation challenge in future mmWave communication systems. ...Furthermore, in order to improve signal coverage of mmWave networks, network densification has to be used at the same time. However, the concurrent use of directional transmission and network densification will make the radio resource management (RRM) of dense mmWave network dramatically more complicated than that of microwave network. In order to maximize the sum-rate of the entire network, tedious and complex RRM algorithms are usually needed to obtain good results, which require high complexity of computation. To address this challenge, we proposed a deep learning-based beam management and interference coordination (BM-IC) method in dense mmWave network, through which the conventional complex BM-IC algorithm is transformed into a deep neural network (DNN)-based approximation. Because DNN only requires a series of simple calculations (e.g., some additions and multiplications), the complexity of computation is greatly reduced. Simulation results show that the proposed deep learning-based BM-IC approach can obtain comparable sum-rate to conventional BM-IC algorithm, but with much less computation time. Thus, deep learning could be a powerful tool to mitigate the complexity of RRM problems in dense mmWave networks.
A dual-band textile antenna loaded with an artificial magnetic conductor (AMC) plane is proposed for WLAN applications. Its dual-band operation is enabled by a rectangular patch in the 2.4 GHz band ...and a patch-etched slot dipole in the 5 GHz band. Since the AMC approaches a perfect magnetic conductor (PMC) in the 5 GHz band, the slot dipole can be located close to the ground. The proposed antenna is fully fabricated using textiles except for a feeding connector used for testing purposes and a via. Simulations and experiments agree well and validate that this low profile antenna operates with a good reflection coefficient and a high front-to-back ratio (FBR) within the desired bands.
We have studied RF transmission over various multimode fibers (MMFs) and a standard single-mode fiber, targeting picocellular networks for voice, data, and video applications. Bandwidth requirements ...of MMF links that are based on vertical-cavity surface-emitting laser (VCSEL) have been extensively studied. The performance of the radio-over-fiber link is assessed in terms of the error vector magnitude. Also conducted was a full system analysis, including the investigation of an achievable dynamic range and a noise figure for different low-cost architectures. This was compared to coax-based RF transmission. The IEEE 802.11 a/b/g standard, as well as other applications like radio frequency identification tracking, was considered. For experimental investigations, we have used both commercial wireless access points and a vector signal generator as a signal source, with two types of directly modulated VCSELs - 850-nm sources and 1310-nm high-speed uncooled single-mode AlGaInAs/InP VCSELs. A robust system performance was demonstrated in both 2.4- and 5-GHz RF bands, and record multimode and standard single-mode fiber transmission distances were achieved. A transponder design that can meet system requirements in terms of sensitivity (< -90 dBm) and spurious-free dynamic range (> 95 dBldrHz 2/3 ) for a dual-band wireless LAN (WLAN) fiber-radio picocellular network was developed. A full 14-cell experimental WLAN system with cells of 4-m radius was implemented to study networking issues such as handoff and cochannel interference.
By deploying additional low power nodes (LPNs) within the coverage area of traditional high power nodes (HPNs) and bringing them closer to users, underlay heterogeneous networks (HetNets) can ...significantly boost the overall spectral efficiency (SE) and energy efficiency (EE) through a full spatial resource reuse. Considering that the severe intra-tier interference among dense LPNs and inter-tier interference between LPNs and HPNs are challenging the successful rollout and commercial operations of underlay HetNets, a great emphasis is given towards advanced techniques that take interference control, radio resource allocation, and self-organization into account to enhance both SE and EE in this paper. The interference control techniques presented in this paper are classified as the spatial interference coordination at the transmitter and the interference cancelation at the receiver. For the radio resource allocation, the multi-dimensional optimization, cross-layer optimization, and cooperative radio resource management are comprehensively summarized. The self-configuration, self-optimization, and self-healing techniques for the self-organized underlay HetNets are surveyed. Furthermore, this paper outlines the potential open issues for underlay HetNets to improve SE and EE when combining with energy harvesting and cloud computing.
With the rapid development of wireless communication technology, various indoor location-based services (ILBSs) have gradually penetrated into daily life. Although many other methods have been ...proposed to be applied to ILBS in the past decade, WiFi-based positioning techniques with a wide range of infrastructure have attracted attention in the field of wireless transmission. In this survey, the authors divide WiFi-based indoor positioning techniques into the active positioning technique and the passive positioning technique based on whether the target carries certain devices. After reviewing a large number of excellent papers in the related field, the authors make a detailed summary of these two types of positioning techniques. In addition, they also analyse the challenges and future development trends in the current technological environment.
This paper uses an information-theoretic lens to view the error bound of wireless local area network (WLAN) localization, which is recognized as one of the superior candidate localization techniques ...in the GPS-denied environment. Interestingly, we analogize the process of WLAN localization into one of information propagation in a parallel Gaussian noisy channel, and then derive the corresponding localization error bound from the channel capacity of the analogical information propagation system. Experimental results show that compared with the widely-known Cramer-Rao Lower Bound (CRLB), the proposed approach performs better in localization error bound estimation under most of the cases of different access point deployment and reference point calibration.
In upcoming very high-speed wireless LANs (WLANs), the physical (PHY) layer rate may reach 600 Mbps. To achieve high efficiency at the medium access control (MAC) layer, we identify fundamental ...properties that must be satisfied by any CSMA-/CA-based MAC layers and develop a novel scheme called aggregation with fragment retransmission (AFR) that exhibits these properties. In the AFR scheme, multiple packets are aggregated into and transmitted in a single large frame. If errors happen during the transmission, only the corrupted fragments of the large frame are retransmitted. An analytic model is developed to evaluate the throughput and delay performance of AFR over noisy channels and to compare AFR with similar schemes in the literature. Optimal frame and fragment sizes are calculated using this model. Transmission delays are minimized by using a zero-waiting mechanism where frames are transmitted immediately once the MAC wins a transmission opportunity. We prove that zero-waiting can achieve maximum throughput. As a complement to the theoretical analysis, we investigate the impact of AFR on the performance of realistic application traffic with diverse requirements by simulations. We have implemented the AFR scheme in the NS-2 simulator and present detailed results for TCP, VoIP, and HDTV traffic. The AFR scheme described was developed as part of the IEEE 802.11n working group work. The analysis presented here is general enough to be extended to proposed schemes in the upcoming 802.11n standard. Trends indicated in this paper should extend to any well-designed aggregation schemes.
The emergence of two new technologies, namely, software defined networking (SDN) and network function virtualization (NFV), have radically changed the development of network functions and the ...evolution of network architectures. These two technologies bring to mobile operators the promises of reducing costs, enhancing network flexibility and scalability, and shortening the time-to-market of new applications and services. With the advent of SDN and NFV and their offered benefits, the mobile operators are gradually changing the way how they architect their mobile networks to cope with ever-increasing growth of data traffic, massive number of new devices and network accesses, and to pave the way toward the upcoming fifth generation networking. This survey aims at providing a comprehensive survey of state-of-the-art research work, which leverages SDN and NFV into the most recent mobile packet core network architecture, evolved packet core. The research work is categorized into smaller groups according to a proposed four-dimensional taxonomy reflecting the: 1) architectural approach, 2) technology adoption, 3) functional implementation, and 4) deployment strategy. Thereafter, the research work is exhaustively compared based on the proposed taxonomy and some added attributes and criteria. Finally, this survey identifies and discusses some major challenges and open issues, such as scalability and reliability, optimal resource scheduling and allocation, management and orchestration, and network sharing and slicing that raise from the taxonomy and comparison tables that need to be further investigated and explored.
The problem of spectrum scarcity has raised the prospect of coexisting network. For example, long-term evolution-licensed-assisted access (LTE-LAA & Wi-Fi) can operate in the same frequency band. ...However, interference between the two different radio access technologies can severely reduce the performances of both networks. To mitigate this interference, the concept of an almost blank subframe (ABS) has been proposed. However, because the LTE-LAA macrocell must remain silent, this provides no incentive for its throughput enhancement. In this letter, we propose a transaction between LTE-LAA and Wi-Fi using ABS together with offloading. We model a time-resource utility model by jointly considering the resource consumed for ABS and offloading, and then formulate a coalition game. To achieve the solution of a coalition game, we consider two fairness concepts: min-max and Shapley fairness. We then verify the performance of the proposed game using simulations. It is shown that the proposed game model can improve resource utilization through the joint use of ABS and offloading.
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