Enhancing PMIPv6 for Better Handover Performance among Heterogeneous Wireless Networks in a Micromobility Domain

This paper analyzes the reduction of handover delay in a network-based localized mobility management framework assisted by IEEE 802.21 MIH services. It compares the handover signaling procedures with host-based localized MIPv6 (HMIPv6), with network-based localized MIPv6 (PMIPv6), and with PMIPv6 assisted by IEEE 802.21 to show how much handover delay reduction can be achieved. Furthermore, the paper proposes and gives an in-depth analysis of PMIPv6 optimized with a handover coordinator (HC), which is a network-based entity, to further improve handover performance in terms of handover delay and packet loss while maintaining minimal signaling overhead in the air interface among converged heterogeneous wireless networks. Simulation and analytical results show that indeed handover delay and packet loss are reduced

Syntbesis and Properries of the Selective Antimuscarinic Agent Cyclohexylphenyl(3-piperidinopropyl)silanol

Die Synthese des selektiven Antimuskarinikums Cyclohexylpheny\{3-piperidinopropyl)sila· nol (1 b) wird beschrieben. 1 b wurde - ausgehend von (3·Chlorpropyl)trimethoxysilan - durch eine vierstufige Reaktionsfolge erhalten und als Hydrochlorid 2b mit einer Gesamtausbeute von etwa 45°/o isoliert. - 1 b ist aufgrund seiner großen pharmakologischen Se· lektivität zu einer Standardsubstanz in der experimentellen Pharmakologie bei der Differenzierung von Muskarinrezeptoren geworden.The synthesis of thc selective antimuscarinic agent cyclohexylphenyl(3-piperidinopropyl)silanol (1 b) is described. Starting with (3-chloropropyl)trimethoxysilane, I b was obtained by four reaction steps and isolated as hydrochloride 2b with a total yield of about 45°/o. - Because of its high pharmacological selectivity 1 b has become a reference drug in experimental pharmacology for the differentiation of muscarinic rcceptors

Molekülstruktur der Akarizide Chlortrineophylstannan, Chlortris[(dimethylphenylsilyl)methyl]stannan und Trineophyl(1,2,4-triazol-1-yl)stannan-hemihydrat sowie des 2,5-Dimethyl-2,5-diphenylhexans (Bineophyl)

Die Kristall- und Molekülstrukturen der Akarizide Chlortrineophylstannan (Ia), Chlortris[ ( dimethylphenylsilyl)methyl]stannan (tb) und Trineophyl(1,2,4-triazol-1- yl)stannan-hemihydrat (2a · 0.5H$_2$0) wurden durch Einkristall-Röntgenstrukturanalysen bestimmt. Zu V ergleichszwecken wurde ausserdem die Struktur des 2,5-Dimethyl-2,5-diphenylhexans (Bineophyl, 4) untersucht. Die Knüpfung von drei sehr raumerfüllenden N eophyl-Resten an ein Zinnatom führt zu einer deutlichen Verzerrung der tetraedrischen Geometrie [ta: C-Sn-C 117.2°, C-Sn-Cl99.7°; 2a·0.5H20: C-Sn-C 116.9° (Mittelwert), C-Sn-N 100.2° (Mittelwert)]. Austausch der zentralen Kohlenstoffatome in den Neophyt-Substituenten von la durch Siliciumatome führt zu einer Verringerung des Raumbedarfs und dadurch zu einer erkennbaren Angleichung an die tetraedrische Geometrie [lb: C-Sn-C 113.3° (Mittelwert), C-Sn-Cl 105.3° (Mittelwert)].The crystal and molecular structures of the acaricides chlorotrineophylstannane (ta), chlorotris[( dimethylphenylsilyl)methyl]stannane (tb ), and trineophyl(1,2,4-triazol- 1-yl)stannane hemihydrate (2a · 0.5H$_2$0), have been determined by single-crystal X-ray diffraction studies. The structure of 2,5-dimethyl-2,5-diphenylhexane (4) was also investigated for comparison. Binding of three very bulky neophyl ligands around tin causes serious distortion of the tetrahedral geometry [la: C-Sn-C 117.2°, C-Sn-Cl 99.7°; la · 0.5H20: C-Sn-C 116.9° (mean), C-Sn-N 100.2° (mean)]. Replacement of the central carbon atoms in the neophyl substituents of ta by silicon atoms Ieads to a decrease in steric strain and hence to a much smaller distortion of the tetrahedral geometry [lb: C-Sn-C 113.3° (mean), C-Sn-Cl105.3° (mean)]

Synthese und Eigenschaften des selektiven Antimuscarinikums Sila-Hexocyclium-methylsulfat

Sila-Hexocyclium-methylsulfat (7b), ein Silicium-Analogon des therapeutisch eingesetzten Antimuscarinileums Hexocyclium-methylsulfat (7a), wurde durch eine sechsstufige Synthese - ausgehend von (CH$_3$0)$_3$SiCH$_2$Cl - dargestellt (Gesamtausbeute 16%). Außerdem wurden die hiervon abzuleitende freie Base 9b (fünfstufige Synthese, ausgehend von (CH$_3$0)$_3$SiCH$_2$O; Gesamtausbeute 29%) und das strukturverwandte (Aminomethyl)silanol 13 (dreistufige Synthese, ausgehend von cyclo-C$_6$H$_{11}$(C$_6$H$_5$)Si(OCH$_3$)CH$_2$Cl, Gesamtausbeute 46$) synthetisiert. 7b ist ein hochwirksames und selektives Antimuscarinikum, das in der experimentellen Pharmakologie aufgrund seines bemerkenswerten Selektivitätsprofils zur Klassifizierung von Subtypen muscarinischer Rezeptoren eingesetzt wird.Sila-hexocyclium methyl sulfate (7b), a silicon analogue of the antimuscarinic agent hexocyclium methyl sulfate (7a), has been prepared by a six-step synthesis (total yield 16%) starting from (CH$_3$O)$_3$SiCH$_2$Cl. In addition, the corresponding free base (a five-step synthesis, starting from (CH$_3$O)$_3$SiCH$_2$Cl; total yield 29%) and the structurally related (aminomethyl)silanol (a three-step synthesis, starting from cyclo-C$_6$H$_{11}$(C$_6$H$_5$)Si(OCH$_3$)CH$_2$Cl; total yield 46%) have been synthesized. 7b is a potent and highly selective antim.uscarinic agent. Because of its remarkable selectivity profile, it is used in experimental phannacology to classify the various subtypes of musearlnie receptors

Sila-Procyclidin: Eine neue Synthese sowie Untersuchungen zur peripheren und zentralen anticholinergen Wirkung

Sila-Procyclidin (1 b) sowie dessen Derivate 2b (Sila-Tribexyphenidyl), 3b und 4b (Sila-Cycrimin) wurden - ausgehend von Cl$_3$SiCH$_2$Cl - durch eine neue, sechsstufige Synthese mit einer Gesamtausbeute von 16 (lb), t9 (2b), 8 (3b) bzw. 7% (4b) dar· gestellt. - Vergleichende in-vivo-Untcrsuchungen (Maus, per-osApplikation) hinsichtlich der peripheren und zentralen auticholincrgen Wirkung haben gezeigt, daß die Silicium-Verbindung 1 b dem Kohlenstoff-Analogon Ia (Procyclidin) überlegen ist.Starting with Cl$_3$SiCH$_2$Cl. sila-procycUdine (I b) as well as its derivatives 2b (sila-trihexyphenidyl), 3b, and 4b (sila-cycrimine) were prepared by a new six-step synthesis witb a total yield of 16 (lb), 19 (2b), 8 (31) aud 7% (4b), respectively. - Comparative in vivo investigations (mice per os administration) with respect to the peripheral and centrat anticholinergic activity bavc shown that the silicon compound 1 b is advantageous over the c:arbon aualogue t a (procyclidine)

Crystal and molecular structures of the (R)-enantiomer and the racemate of the antimuscarinic agent (cyclohexyl)phenyl[2-(pyrrolidin-1-yl)ethyl]silanol (sila-procyclidine)

The crystal structures of the (R)-enantiomer (2b) and the racemate (1 b) of (cyclohexyl)phenyl[2- (pyrrolidin-1-yl)ethyl]silanol (sila--procyclidine) have been determined by X -ray structural analysis. The absolute configuration of (2b) was established. (2b) crystallizes in the orthorhombic space group P2$_1$2$_1$2$_1$, with a = 15.221 (1 ), b = 17.967(1 ), c = 6.463(1) A, and Z = 4. (1 b) crystallizes in the monoclinic space group P2$_1$/c, with a = 6.441 (1 ), b = 17.1 82(7), c = 16.707(4) A, ß = 1 03.86(2r, and Z = 4. The structures were refined to respective R factors of 0.044 and 0.058. The molecular conformation of sila-procyclidine is identical in the two different structures. lntermolecular 0-H • • • N hydrogen bonding is observed in both crystallattices.ln (1 b) (R)- and (S)-configurated molecules form centrosymmetric dimers, in (2b) the (R)-configurated molecules are linked into infinite chains parallel to the c axis. The (R)-configurated sila--procyclidine (2b) has higher affinity for ileal and atrial muscarinic receptors of the guinea pig than the (S)-configurated enantiomer (3b)

IEEE802.21 Optimized handover delay for proxy Mobile IPV6

Next generation wireless networks are envisaged to be a combination of different but complementary access tech-nologies. Interworking of these heterogeneous wireless networks will provide ubiquitous access to roaming net-work users. Thus, a seamless mobility mechanism with low handover delay to maintain active communication flows during handover across these networks is required. Sev-eral solutions, mainly host-based localized mobility man-agement schemes, have been widely proposed to reduce handover delay in heterogeneous wireless networks. How-ever, the handover delay remains high and unacceptable for delay-sensitive services. Moreover, host-based mobility management schemes involve the mobile node in mobility-related signaling hence effectively increasing the handover delay. This paper analyzes the reduction of handover delay in a network-based localized mobility management frame-work assisted by IEEE 802.21 Media Independent Hand-over services. It compares the handover signaling proce-dures with host-based localized Mobile IPv6 (HMIPv6), with network-based Mobile IPv6 (PMIPv6), and with PMIPv6 assisted by IEEE 802.21 to show how much handover delay reduction can be achieved. I