107,417 research outputs found
Performance Evaluation of Distributed-Antenna Communications Systems Using Beam-Hopping
No full textDigital beamforming (DBF) techniques are capable of improving the performance of communications systems significantly. However, if the transmitted signals are conflicted with strong interference, especially, in the direction of the transmitted beams , these directional jamming signals will severely degrade the system performance. In order to efficiently mitigate the interference of the directional jammers, in this contribution a beam-hopping (BH) communications scheme is proposed. In the proposed BH communications scheme, only one pair of the beams is used for transmission and it hops from one to the next according to an assigned BH pattern. In this contribution a range of expressions in terms of the average SINR performance have been derived, when both the uplink and downlink are considered. The average SINR performance of the proposed BH scheme and that of the conventional single-beam (SB) as well as multiple-beam (MB) assisted beam-processing schemes have been investigated. Our analysis and results show that the proposed BH scheme is capable of efficiently combating the directional jamming, with the aid of utilizing the directional gain of the beams generated by both the transmitter and the receiver. Furthermore, the BH scheme is capable of reducing the intercept probability of the communications. Therefore, the proposed BH scheme is suitable for communications, when several distributed antenna arrays are available around a mobile
Mobile Social Networking aided content dissemination in heterogeneous networks
No full textSince more and more mobile applications are based on the proliferation of social information, the study of Mobile Social Net-works (MSNs) combines social sciences and wireless communications. Operating wireless networks more efficiently by exploiting social relationships between MSN users is an appealing but challenging option for network operators. An MSN-aided content dissemination technique is presented as a potential ex-tension of conventional cellular wireless net-works in order to satisfy growing data traffic. By allowing the MSN users to create a self-organized ad hoc network for spontaneously disseminating contents, the network operator may be able to reduce the operational costs and simultaneously achieve an improved network performance. In this paper, we first summarize the basic features of the MSN architecture, followed by a survey of the factors which may affect MSN-aided content dissemination. Using a case study, we demonstrate that one can save resources of the Base Station (BS) while substantially lowering content dissemination delay. Finally, other potential applications of MSN-aided content dissemination are introduced, and a range of future challenges are summarized
Aporia chunhaoi Hu, Zhang & Yang 2021, sp. nov.
No full text<i>Aporiachunhaoi</i> Hu, Zhang & Yang sp. nov. <p> <i>Aporia lhamo</i> (Oberthür, 1893); in Wu & Hsu (eds.). 2017. Butterflies of China, 1: 375 (text), 376 (plate), figs. 2–4.</p>Published as part of <i>Hu, Shao-Ji, Zhang, Hui-Hong & Yang, Yang, 2021, A New Species of Aporia (Lepidoptera: Pieridae) from Northwest Yunnan, China with Taxonomic Notes on Its Similar Sympatric Taxa, pp. 1-10 in Zootaxa 4963 (1)</i> on page 2, DOI: 10.11646/zootaxa.4963.1.1, <a href="http://zenodo.org/record/4711186">http://zenodo.org/record/4711186</a>
Syneches apiciflavus Yang, Yang & Hu 2002
No full textSyneches apiciflavus Yang, Yang & Hu, 2002 Syneches apiciflavus Yang, Yang & Hu, 2002: 733. Material examined. – 3 males, 1 female, Guangdong: Liuxihe, 16 Jul.2003, coll. Xingyue Liu (CAU); 1 male, 6 females, Guangdong: Shixing, Chebaling National Nature Reserve, 10 Jul.2003, coll. Shuwen An (CAU). Diagnosis. – Antenna blackish, but first flagellomere with yellow apex. Femora yellow with extreme tip blackish. Wing hyaline; stigma rather short, wider than long. R4+5 and M1 parallel apically. Distribution. – China (Guangdong, Hainan).Published as part of Yang, Ding & Grootaert, Patrick, 2004, Revision Of The Species Of Syneches From Guangdong (Diptera: Empidoidea: Hybotinae), pp. 347-350 in Raffles Bulletin of Zoology 52 (2) on pages 347-348, DOI: 10.5281/zenodo.461894
PIN generation using EEG : a stability study
No full textIn a previous study, it has been shown that brain activity, i.e.
electroencephalogram (EEG) signals, can be used to generate personal
identification number (PIN). The method was based on brain–computer
interface (BCI) technology using a P300-based BCI approach and showed that
a single-channel EEG was sufficient to generate PIN without any error for
three subjects. The advantage of this method is obviously its better fraud
resistance compared to conventional methods of PIN generation such as
entering the numbers using a keypad. Here, we investigate the stability of these
EEG signals when used with a neural network classifier, i.e. to investigate the
changes in the performance of the method over time. Our results, based on
recording conducted over a period of three months, indicate that a single
channel is no longer sufficient and a multiple electrode configuration is
necessary to maintain acceptable performances. Alternatively, a recording
session to retrain the neural network classifier can be conducted on shorter
intervals, though practically this might not be viable
Aporia chunhaoi Hu, Zhang & Yang 2021, sp. nov.
No full text<i>Aporiachunhaoi</i> Hu, Zhang & Yang sp. nov. <p> <b>HOLOTYPE</b>: ♂, Tacheng (2,800–3,000 m), Yulong County, Lijiang Prefecture, N.W. Yunnan, China, 2020– VII–15-20, Y. Yang leg. [KIZ 0127556]. PARATYPES: 4♂♂, the same data as the holotype, Y. Yang leg. [KIZ 0127557–0127560]; 7♂♂, the same data as the holotype, Y. Yang leg. [SJH]; 2♂♂, the same locality as the holotype, 2020–VII–25-30, Y. Yang leg. [SJH]; 1♀, the same collecting data, [KIZ 0127562]; 2♂♂, Ludian to Weixi Road (3,000 m), Weixi County, Diqing Prefecture, N.W. Yunnan, China, 2014– VI –13, C. H. Wang leg. [CHW]; 1♂, ditto, 2014– VI –13, X. M. Jing leg. [CHW]; 1♂, Shiba (2,600 –2,700 m), Deqen County, Diqing Prefecture, N.W. Yunnan, China, 2020–VII–5-6, Y. Yang leg. [KIZ 0127561]; 1♂, the same collecting data, [SJH].</p>Published as part of <i>Hu, Shao-Ji, Zhang, Hui-Hong & Yang, Yang, 2021, A New Species of Aporia (Lepidoptera: Pieridae) from Northwest Yunnan, China with Taxonomic Notes on Its Similar Sympatric Taxa, pp. 1-10 in Zootaxa 4963 (1)</i> on page 9, DOI: 10.11646/zootaxa.4963.1.1, <a href="http://zenodo.org/record/4711186">http://zenodo.org/record/4711186</a>
Sialis jianfengensis Yang, Yang & Hu
No full textSialis jianfengensis Yang, Yang & Hu (Figs. 2 & 10) Sialis jianfengensis Yang, Yang & Hu, 2002: 275. Diagnosis. Head orange with frons and clypeus black; pronotum yellowish brown with anterior margin dark; wings narrow, 1 / 3 of length. Female. Forewing length about 14–18 mm, hindwing length 13–16 mm. Head orange, vertex somewhat brown, frons and clypeus black. Compound eyes brown. Antenna black. Mouthparts black. Thorax black; pronotum yellowish brown with anterior margin blackish brown. Legs black. Wings narrow, 1 / 3 of length, grayish brown, forewings proximally darkened; veins dark brown. Abdomen black. Seventh sternite with posterior margin slightly elevated. Eighth sternite broad, subquadrate, moderately sclerotized except for a narrow median area. Ninth abdominal segement separated with a pair of membranous plates. Male. Unknown. Material examined. Holotype Ψ, CHINA: Hainan, Jianfengling, 1982. II. 22 / 26, H.Q. Chen & K.Z. Yun. Paratypes: 2 ΨΨ, same data as holotype. Distribution. China (Hainan). Remarks. This species distinctly differs from all the other Sialis species by the body coloration and the narrow wings. It seems to be related to some Protosialis species. In Protosialis species, the costal regions of the forewings are weakly dilated, and R 2 + 3 is only bifurcated. The lack of the male makes it difficult to determine the exact generic and specific status of this species. However, it is herein considered to be a true Sialis species by the distinctly dilated costal regions of the forewings and the four branched R 2 + 3.Published as part of Liu, Xingyue & Yang, Ding, 2006, Revision of the genus Sialis from Oriental China (Megaloptera: Sialidae), pp. 23-35 in Zootaxa 1108 on pages 27-29, DOI: 10.5281/zenodo.17149
Multi-Functional Antenna Array Assisted MC DS-CDMA Using Downlink Preprocessing Based on Singular Value Decomposition
No full textIn this contribution we propose and investigate a transmitter preprocessing scheme designed for downlink transmission in multicarrier direct-sequence code-division multiple-access (MC DS-CDMA) systems using multiple base-station antenna arrays, where each antenna array employs multiple array elements. The transmitter preprocessing scheme is derived based on the singular value decomposition (SVD). Our transmitter preprocessing design is capable of supporting a high number of MC DS-CDMA users, while maintaining a high diversity gain at a low detection complexity at the remote mobile stations (MSs). The characteristics of MC DS-CDMA using the proposed transmitter preprocessing scheme are discussed and the achievable bit-error-rate (BER) performance is investigated, when assuming that each subcarrier experiences flat Rayleigh fading. Our simulation results demonstrate that for a SVD-assisted MC DS-CDMA system using M distinct transmit antenna arrays and time (T)-domain spreading sequences of length Ne chips, the number of users supported can be as high as MNe, since Ne and M number of users may be distinguished in the T-domain and spatial-or S-domain, respectively. Furthermore, the SVD-assisted MC DSCDMA system is capable of supporting M ?Ne number of users at a near single-user BER performance
Homoneura (Homoneura) henanensis Yang, Zhu & Hu 1999
No full textHomoneura (Homoneura) henanensis Yang, Zhu & Hu, 1999 Homoneura (Homoneura) henanensis Yang, Zhu & Hu, 1999: 211. Type locality: China (Henan). Holotype in CAUC. Homoneura (Homoneura) beijingensis Gao & Yang, in Wang, Gao & Yang, 2012: 36. syn. nov. Type locality: China (Beijing). Diagnosis. Wing with brown apical spots on R 2 + 3, R 4 + 5 and M 1 extending to tip of veins; apical spot on R 2 + 3 distinctly separated from apical spot on R 4 + 5; apical spots on R 4 + 5 and M 1 separated, but gray area present between apical spots on R 4 + 5 and M 1; a brown quadrate spot on R 4 + 5 behind middle point of distance between r-m and dm-cu; a brown wide stripe-like spot on dm-cu. Male genitalia: epandrium with a row of long setulae on ventral margin in lateral view; surstylus consisting of an acute apical process, directed downward and a slender knife-like with dense setulae on dorsal margin in lateral view; pregonite long, with two small acute processes on inner margin and an acute apical process directed outside in ventral view; postgonite short, with a sharp triangular process directed inside in ventral view; aedeagus narrow apically in ventral view and knife-like distally in lateral view, but length of aedeagal apodeme variable. Distribution. China (Beijing, Henan).Published as part of Shi, Li & Yang, Ding, 2014, Supplements to species groups of the subgenus Homoneura in China (Diptera: Lauxaniidae: Homoneura), with descriptions of twenty new species, pp. 1-117 in Zootaxa 3890 (1) on page 29, DOI: 10.11646/zootaxa.3890.1.1, http://zenodo.org/record/25063
Ant-colony-based multiuser detection for multifunctional-antenna-array-assisted MC DS-CDMA systems
No full textA novel Ant Colony Optimization (ACO) based Multi-User Detector (MUD) is designed for the synchronous Multi-Functional Antenna Array (MFAA) assisted Multi-Carrier Direct-Sequence Code-Division Multiple-Access (MC DS-CDMA) uplink (UL), which supports both receiver diversity and receiver beamforming. The ACO-based MUD aims for achieving a bit-error-rate (BER) performance approaching that of the optimum maximum likelihood (ML) MUD, without carrying out an exhaustive search of the entire MC DS-CDMA search space constituted by all possible combinations of the received multi-user vectors. We will demonstrate that regardless of the number of the subcarriers or of the MFAA configuration, the system employing the proposed ACO based MUD is capable of supporting 32 users with the aid of 31-chip Gold codes used as the T-domain spreading sequence without any significant performance degradation compared to the single-user system. As a further benefit, the number of floating point operations per second (FLOPS) imposed by the proposed ACO-based MUD is a factor of 108 lower than that of the ML MUD. We will also show that at a given increase of the complexity, the MFAA will allow the ACO based MUD to achieve a higher SNR gain than the Single-Input Single-Output (SISO) MC DS-CDMA system. Index Terms—Ant Colony Optimization, Multi-User Detector, Multi-Functional Antenna Array, Multi-Carrier Direct-Sequence Code-Division Multiple-Access, Uplink, Near-Maximum Likelihood Detection
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