A fundamental assumption of the tcp protocol is that packet losses indicate congestion on the network. This is a problem when using tcp over wireless links, because a noisy radio transmission may erroneously indicate congestion and thereby reduce the tcp sending rate. Two partial solutions, which improve the quality of the radio link, are power control and link-layer retransmissions. We conside...

Mobile users are facing the fact that many heterogenous radio access technologies coexist, ranging from wireless LANs to cellular systems. No technology has emerged as a common and universal solution which makes the current trends today toward the design of AllIP wireless networks, where radio cells are under the control of IP Access Routers for signalling and data transmission. In such network...

Mobile users are facing the fact that many heterogenous radio access technologies coexist, ranging from wireless LANs to cellular systems. No technology has emerged as common and universal solution which makes the current trends today toward design of All-IP wireless networks, where radio cells are under the control of IP Access Routers for signalling and data transmission. In such as networks,...

The current trends in vehicular adhoc networks are bringing a variety of changes to the existing one. The primary focuses in the area of vehicular adhoc networks are connectivity and file distribution which is broadcast by roadside units to the onboard units during handoffs. The connectivity of vehicular adhoc network can be improved by the use of cognitive radio networks with interference mana...

We present four Mpc-sized radio galaxies which consist of a pair of double-lobed radio sources, aligned along the same axis, and with a coinciding radio core. We have called these peculiar radio sources ‘double-double’ radio galaxies (DDRG) and propose a general definition of such sources: A ‘double-double’ radio galaxy consists of a pair of double radio sources with a common centre. Furthermor...

Research in the design of ultra-wideband (UWB) radio systems suggests di erent kinds of signal design criteria. After an introduction to UWB radio, a variety of sequence design problems, motivated by UWB system constraints, will be presented. Design for time-hopping, for spectral atness, for rapid acquisition, and for multiple access will be discussed, and some sample designs will be presented.

radio-protectors are agents that protect human cells and tissues from undesirable effects of ionizing radiation by mainly scavenging radiation-induced free radicals. although chemical radio-protectors diminish these deleterious side effects they induce a number of unwanted effects on humans such as blood pressure modifications, vomiting, nausea, and both local and generalized cutaneous reaction...

background: media advertisements especially radio and tv are one of the most important and effective ways for health promotion and consumption of healthy productions worldwide. ministry of health and some other ministries in iran agreed to control and restrict the advertising of unhealthy products and services. therefore, adequate supervision and monitoring should be done in this field.  a cont...