Advanced Wireless Technology Evolution of Wireless

Transcript:Advanced Wireless Technology Evolution of Wireless:
Advanced Wireless Technology Evolution of Wireless Technology Traditional Telephonic System It uses Public Switched Telephone Network (PSTN), also known as Plain Old Telephone Service (POTS) The PSTN relies on circuit switching. The connection established between the two phones is called a circuit. History of PSTN Working of PSTN The circuit-switched PSTN opens up a continuous connection between two phones, that begins with a dial tone and ends when the phone is hung up. To start it is required an individual subscriber, or a group of subscribers Individual subscribers connect directly to the local exchange, while businesses(group) often use a private branch exchange (PBX) to manage all their connections. The call starts with the actual phone and either connects directly to the Local Exchange or to the PBX and then to the Local Exchange, if the call comes from a business with multiple lines. From the local exchange network, depending on where the call is going, it is pushed to international carriers, interexchange carriers, cellular providers, or internet service providers. The number of layers of technology a call passes through varies depending on where the call is destined. Components of PSTN The PSTN is comprised of a complex web of interconnection nodes and transmissions links. There are four different types of nodes: customer premises equipment (CPE), transmission, service, and switching Transmission links constitute the physical wires or fiber CPE:The CPE node is the equipment on site where the call originates. That could be an individual subscriber line or a PBX. Transmission: The transmission node consists of the equipment and media that carry information between nodes of a network. This can include things like amplifiers, repeaters, multiplexers, digital cross-connect systems, and digital loop carriers. Service: The service node is responsible for signaling. This means determining when to setup, hold, charge, and release connections, and getting that information to the correct outlets that maintain and bill for each section of the network. Switches Local Switches The Tandem Office (or junction network) The Toll Office the International Gateway Disadvantages The infrastructure is "older" CAT3 copper wire and can't run high speed data reliably. The infrastructure was designed to carry 3Khz analog voice The infrastructure has been spliced and patched back together over the years. It's extremely expensive to replace it. Subject to outages from things like falling trees, which cellular service is not. Doesn't support mobility. VOIP Voice over Internet Protocol (VoIP) is a