In this paper we determine the optimal fraction c∗ of the uplink channel capacity that should be dedicated to the contention channel in a DOCSIS cable network in order to minimize its mean response time. For this purpose, we have developed an open queueing network with a non-standard form of blocking consisting of tens to hundreds of nodes. The network contains several types of customers that e...

Several decades of research in underwater communication and networking has resulted in novel and innovative solutions to combat challenges such as long delay spread, rapid channel variation, significant Doppler, high levels of nonGaussian noise, limited bandwidth and long propagation delays. Many of the physical layer solutions can be tested by transmitting carefully designed signals, recording...

The paper describes the upstream MAC protocol employed by the HP cable-modem for hybridber-coax networks. The protocol, called MXL, divides the upstream channel into two logical channels: a contention channel and a reserved channel. Cablemodem stations that need to send data have to reserve su cient bandwidth in the reserved channel. In order to send their reservation request, the stations have...

The rapid international development of the mobile phone business has led to significant advances in communications engineering. However, the experience base for underwater acoustic communications is much more limited. Meanwhile, the ocean channel has unique characteristics, so that one cannot assume radio modulation schemes are suitable for acoustic communications in the ocean (and vice versa)....

For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks...

En el presente trabajo se describe la implementación y ensayo de un demodulador FSK, en marco Re-Ingeniería modem para comunicaciones navales. El mismo desarrolló sobre una FPGA Spartan 6 XCSLX25 con su código VHDL. Para las pruebas realizaron modulaciones microcontrolador STM32F407 donde agregaron distintos niveles ruido poner a prueba sistema.

Applications of underwater sensor networks involve environmental monitoring, disaster prevention, and resource detection. As the importance of these applications has recently grown, underwater sensor networks made up of sensor nodes have to be further investigated. However, little research has been performed to develop an underwater sensor node with communication functionality. In an underwater...