afewpowerfulnodesenhancemobilenetworkconnectivity(编辑修改稿)

afewpowerfulnodesenhancemobilenetworkconnectivity(编辑修改稿)内容摘要：

h submarine detection. In recent years, interest has shifted to more mercial applications. Today, various unmanned submersibles employ underwater munications systems. These include robots, remotely operated underwater vehicles (ROVs), and unmanned underwater vehicles (UUVs), which are replacing divers in performing a variety of offshore tasks. As a spreadspectrum system, chirp slope keying (CSK) utilizes a datamodulated signal with its energy spread over a bandwidth that is much greater than the rate of information being transmitted. Chirp slope keying Chirp signals in digital munications were apparently originally suggested by M. R. Winkler3 in 1962 and then idea is to use a pair of linear chirps that have opposite chirp rates for binary signaling. Binary chirp signals, or what Berni4 called linear frequency sweeping (LFS), pared favorably to frequencyshiftkeying (FSK) and phaseshiftkeying (PSK) in coherent channels. In noncoherent channels LFS was considered less appealing because of the requirement for a phase recovery system. Our simulation results show considerable improvement in performance in the signaltonoise (SNR) ranges of interest in performance when binary CSK is used instead of binary PSK in the Rayleigh fading ,6 A linear plex chirp signal may be modeled as in (1): The real part of sc(t) is used as the transmitted signal, with the frequency slope μ indicating the transmitted bit. In terms of maximum and minimum instantaneous frequencies, fmax and fmin, and the signaling interval T, an ‗up‘ chirp is represented as in (2) while a ‗down‘ chirp is represented by (3): 5 The binary information stream {Bi} selects the chirp pulses {pi(t)} to be transmitted at each signaling interval as follows: Results Monte Carlo simulations were performed in the additive white Gaussian noise (AWGN) and the Rayleigh fading channels. Figure 1 shows the advantage of CSK over PSK in the noisy Rayleigh fading model with a ratio of bandwidth to information rate of 100. Figure 1. Binary chirp slope keying (CSK) has an advantage over binary phaseshiftkeying (PSK) in the Rayleigh channel, in terms of probability of error (PE) as a function of signaltonoise ratio(SNR). Clearly, for SNR above about , chirp slope keying performs better than standard phase shift keying in the simulated UWA environment. The results shown in Figure 1 represent the performance for the standard coherent correlation receiver with perfect phase recovery. Joint timefrequency techniques may be used to gain performance advantages at the expense of putational plexity. This is exemplified in Figure 2, which gives results for CSK in the AWGN channel both for the standard timedomain correlation detector and for a joint timefrequency detector,6 which uses the Wigner distribution7 and the Radon transform. The Wigner distribution is used to obtain the frequency vs. time image spectrum of the received signal. The Radon transform, by projection of the image intensity along a radial line oriented at a specific angle, can then determine the slope, thereby finishing the demodulation process. 6 Figure 2. Probability of error versus SNR for BCSK in the AWGN channel with time and joint timefrequency receivers. Conclusion and future work Our brief discussion of chirp slope keying (CSK) suggests it is a promising alternative to ordinary modulation schemes for underwater acoustical munications. Accurate modeling of the UWA channel is necessary in order to accurately predict system performance. Further work in this area is needed. Investigation of jointtime frequency receivers also may prove useful, especially if efficient algorithms are designed to reduce the putational plexity. Author Edit J. Kaminsky University of New Orleans， Department of Electrical Engineering， New Orleans, LA References: 1. M. Stojanovic, Underwater Acoustic Communications, IEEE Electro Int39。 l, pp. 435440, 1995. 2. A. B. Baggeroer, Acoustic Telemetry An Overview, IEEE J. Oceanic Eng., Vol: OE9, no. 4, pp. 229235, 1984. 3. M. R. Winkler, Chirp Signals for Communications, WESCON Convention Record, Vol: 14, no. 2, 1962. 4. A. J. Berni, W. D. Greeg, On the Utility of Chirp Modulation for Digital Signaling, IEEE Trans. on Commun., Vol: 21, no. 6, pp. 748751, 1973. 5. E. J. Kaminsky, L. Simanjuntak, Chirp Slope Keying for Underwater Communications, Proc. SPIE, Vol: 5778, pp. 894905, 2020. 6. E. Kaminsky, M. Barbu, Receiver structures for underwater acoustical munications using chirp slope keying, Proc. SPIE, Vol: 6201, no. 37, 2020. 7. L. Cohen, Timefrequency distributions A review, Proc. IEEE, Vol: 77, no. 7, pp. 941981, 1989. 7 Enabling smart service delivery in fibertothehome works Elroy Pluk The development of costeffective equipment for the customer and related management systems are both key to successful implementations. With the everincreasing demand for bandwidth, access works are migrating towards optical fiber, and the number of initiatives to roll out fibertothehome (FTTH) works is growing. Service peration and usersatisfaction are important parameters for a successful FTTH rollout,1 so it39。 s of major importance to optimize delivery to the end user. The quality of services is strongly determined at the edge of a work, where the ‗customerpremises equipment‘ (CPE) forms the interface to the end user. An effective CPE provides for all possible services to the end user with great flexibility. However, it should also create a work with the lowest costbase using simple yet powerful management tools. Flexible and open service delivery Our research has focused on delivering a range of services from multiple service providers to numerous users. We selected an architecture with multiple managed Ether ports in bination。