Wireless Networks - Market Growth

In 2001, approximately 1 in 8 people in the world were using mobile telephones. The growth of some vertical wireless data markets is over 80% per year.

Mobile Telephone Service
By 2001, there were 781 million mobile telephone subscribers in the world. Figure 1 shows the recent trend in subscribership to mobile telephone services. Some of the key drivers for continual growth include lower monthly cost of service and pre-paid wireless services. Pre-paid wireless service allows customers with bad or damaged credit to forego the normal credit check required with wireless service and pay for their service before they use it. Many of the new wireless subscribers have credit challenges.


Figure 1: Mobile Telephone Wireless Growth.
Source: GSM MOU

Data Networks
With the demand for high data rate communications solutions, paralleling interest in the Internet, (fueled by easy-to-use application software, its wide array of text, graphics, video and audio content), wireless data market growth has increased substantially. The availability of Internet services over wireless radio channels will be a critical factor in determining overall market growth.

To date, most wireless data applications are non-human in nature. These include applications such as monitoring wireless parking meters, vending machines, and environmental concerns among others. Human access includes the ability to access data available on the Internet, private intranets, new services, and e-mail. The Internet, for example, is being used by businesses for building interactive branding via communication with customers, advertising products and services, publishing product specifications; and acting as a source for point-of-sale applications.

Market growth for wide area wireless data communications services is in the early stages, primarily because wireless data is not yet capable of providing high data transfer rates at a cost comparable to fiber optic cable or wired connectivity. However, the overall market growth of the wireless data market is up. In 1997, there was over 21% growth for circuit switched data (primarily cellular data) and over 89% growth for packet data (ARDIS, RAM, CDPD, and Ricochet).

Data Terminals : Network Interface Card (NIC), LAN Wiring,

Overview
Data networks are telecommunications networks installed and operated exclusively for information exchange between data communication devices (such as computers). Data network types include premises distribution network (PDN), local area networks (LAN’s), metropolitan area networks (MAN’s), and wide area networks (WAN’s). These are hierarchical with the LAN being the base and the WAN being the umbrella architecture.

PANs are short-range data communications systems that are primarily used to interconnect peripheral equipment with a local computer or computing system. LANs are designed to reliably transfer large amounts of data quickly and error-free over a very small area such as an office. MAN’s facilitate LAN-to-LAN information exchange in a local exchange area. WAN’s allow for information exchange between LAN’s in different exchanges normally across LATA boundaries. For example a LAN in Chicago sharing information with a LAN Seattle would do so across a WAN.

A data network is composed of several key parts such as data terminals (e.g., personal computers), network adapters, access wiring, and data distribution nodes (e.g., routers, brouters, and switches). In some data networks, network management/control systems are used to configure, monitor, coordinate, and control the network elements.

Data Terminals
Data terminals are data input and output devices that are used to communicate with a remotely located computer or other data communication device. Data terminals frequently consist of a keyboard, video display monitor, and communication circuitry that can connect the data terminal with the remotely located computer.

The term “data terminal” is often used to describe multiple types of devices including personal computers (PCs), dedicated “dumb” terminals, scientific workstations, and other types of computers that can communicate with other computers or a host computer.

Data terminal equipment (DTE) are devices that capture and serialize information for communication to other communication devices. Data communication equipment (DCE) circuits are assemblies that convert data information into a format that can be transferred through a communication network.

Figure 1 shows data terminals that are connected through a modem to interconnect the data terminals with a remote computer. In this diagram, the data terminals are the DTE and the modems are the DCE.



Figure 1: Data Terminals

Network Interface Card (NIC)
A NIC is a device that adapts the data communication network protocol to a data bus or data interface in a computer. The NIC is installed between a computer network (such as the Ethernet) and a computer data bus (such as a PCI socket). The NIC is usually a PC expansion board connector and operating system. Software in the computer is installed and setup to recognize the NIC card.

LAN Wiring

There are typically three types of wiring used for LAN’s: twisted pair, coax, and fiber. Of these, twisted pair is dominant for several reasons: ease of installation, availability, cost, and speed as a function of relative cost.

Twisted pair comes in a variety of “categories” and is either shielded twisted pair (STP) or unshielded twisted pair (UTP). UTP is the less expensive and the most widely used. STP has an outer copper or foil conductor located just beneath the out sheath of the wire. In areas where there is a significant incidence of electromagnetic interference (EMI), such as around factory floor machinery or hospital radiological/MRI equipment, STP is used.

Twisted pair wire is classified by categories that relate to the data transmission speed at which the wire is capable of passing data. For each category there are manufacturing specifications such as wire quality, insulation characteristics, and number of twists per inch. Generally, the higher the number of twists, the higher the data transmission rate can be.

Routinely LAN cable is four-pair (eight conductors) even though most data communication systems (such as Ethernet) only require 2 pairs (transmit and receive pairs). It is installed with all conductors terminated on each end into patch fields, hub equipment, or office wall plates (jack fields). From the office wall jack the typical PC or peripheral device is connected to the LAN via a wall cord that is also four-pair terminated in RJ-45 modular connectors. Most offices are wired for multiple network connections and in many cases the voice and data wiring is installed together and to the same cable specification (e.g., category 3 and above).

Network Distribution and Routing
Network distribution and routing equipment provides communication paths between the end-user and the services they desire to use (e.g., Internet). There are three basic methods used to distribute in data networks: broadcast (distribution hubs), dedicated paths (switching nodes), and packet-switching (routers).

Hubs broadcast information to all the communication devices that are connected to it. Switches create a physical or logical connection between data communication devices. Routers are intelligent switches that can dynamically route (switch to other routers) packets of data toward their ultimate destination.

Network Access Control
Network access control is a process of coordinating access of data communication devices to a shared communications media (transmission medium). Network access control is a combination of media access control (MAC) and service authorization.

There are two key ways data communication devices can access communication systems: non-contention based and contention based. Non-contention based regularly poll or schedule data transmission access attempts. An example of a non-contention based data communication system is token ring. In the token ring system, only the data communication device that has the token is allowed to transmit. This ensures that other data devices will not interfere with the data transmission. Contention based access control systems allow data communication devices to randomly access the system through the sensing and coordination of busy status and detected collisions. Carrier sense multiple access (CSMA) with collision detection (CSMA/CD) or collision avoidance (CSMA/CA) listen to the data activity first to determine if the systems is not busy (carrier sense) before they begin a transmit request. After the device transmits its required, it waits to hear if the system has acknowledged its required (usually an echo of its original signal). If the CSMA/CD device does not hear an acknowledgement, it will wait a random amount of time before transmitting another data transmission service request.

The CSMA/CA system differs from the CSMA/CD system by the assignment of different access wait periods to different priority groups of devices. This allows high priority devices (such as a system management data terminal) to attempt access before a lower priority device (e.g., web browsing terminal).

Figure 2 shows the key ways networks can control data transmission access: non-contention based and contention based. This diagram shows that non-contention based regularly poll or schedule data transmission access attempts before computers can begin to transmit data. This diagram shows that a token is passed between each computer in the network and computers can only transmit when they have the token.


Figure 2: Data Network Access Control

Because there is no potential for collisions, computers do not need to confirm the data was successfully transmitted through the network. This diagram also shows contention based access control systems allow data communication devices to randomly access the system through the sensing and coordination of busy status and detected collisions. These devices first listen to see if the system is not busy and then randomly transmit their data. Computers in the contention-based systems must confirm that data was successfully transmitted through the network, because there is the potential for collisions.

Data Communications

There are two basic types of data communications: circuit-switched data and packet-switched data. Circuit-switched data provides for continuous data signals while packet-switched data allows for rapid delivery of very short data messages.

Circuit-switched Data
Circuit-switched data is a data communication method that maintains a dedicated communications path between two communication devices regardless of the amount of data that is sent between the devices. This gives to communications equipment the exclusive use of the circuit that connects them, even when the circuit is momentarily idle.

To establish a circuit-switched data connection, the address is sent first and a connection (possibly a virtual non-physical connection) path is established. After this path is setup, data is continually transferred using this path until the path is disconnected by request from the sender or receiver of data.

Figure below shows the basic operation that uses circuit-switched data. In this example, a laptop computer is sending a file to a company’s computer that is connected to the public switched telephone network (PSTN). The laptop computer data communication software requests the destination phone number from the user to connect to the remote computer. This telephone number (the address) is used connect a path through the PSTN switches until the call reaches the destination computer. The dialed number is first connected through local switch #1, port number 4236. This port number is assigned to a memory location in the switch that routes the data connection through a high-speed line, time slot 6 to an IXC switch. The IXC switch then assigns a memory location in its switch to a high-speed line, time slot 3 that connects to local switch #2. Local switch #2 assigns a memory location in its switch to port number 1249. This port connects to the remote computer. Once this path through the network is setup, it remains constant throughout the data communications session regardless of how much data is transferred between the laptop computer and the company’s computer.


Circuit-switched Data

Packet-switched Data
Packet data service provides data transfer in the form of short packets of information. The public telephone network was designed primarily to offer voice services. Shortly after the telephone network was introduced, circuit-switched (continuous) data services were offered. The operation requirements for circuit-switched and packet-switched data services are very different. Circuit-switched data has substantial time and is inefficient for serving sensing control and applications that require small amounts of information. Initially the standard telephone system had to be enhanced (functionally divided) to offer packet data service. However, with the digitization of communications systems, telephone systems operate more like packet data systems.

Typical applications for packet data service include Internet browsing, wireless email, train control system, route guidance, credit card processing and many other applications that benefit from the transmission of data in bursts when communicating.

Packet data systems provide effective use of the resources. Packet data systems only use network equipment resources when there is information to transfer. This provides the advantage of charging only for the amount of information used and increased system efficiency.

A packet is a group of digital bits that is transported and switched through a network of packet switches (often called routers) to their destination. The structure of these packets (digital bit sequence) is arranged in a specific format to allow the determination of the destination address for each packet in addition to the data that is being transported. Optionally, the packet structure may include other information such as the packet originator and error protection bits.

Transmitting data through a packet network involves dividing data files into small packets (typically under 100 bytes of information). A packet data system divides large quantities of data into small packets for transmission through a switching network that uses the addresses of the packets to dynamically route these packets through a switching network to their ultimate destination. When a data block is divided, the packets are given sequence numbers so that a packet assembler/disassembler (PAD) device can recombine the packets to the original data block after they have been transmitted through the network.

Figure below shows the basic operation that uses packet-switched data. In this example, a laptop computer is sending a file to a company’s remote computer that is connected to a packet data network. The laptop computer data communication software requests the destination address for the packets for the user to connect to the remote computer (202.196.22.45). In this example, the source computer divides the data file into three parts and adds the packet address to each of the 3 data packets. The packets are sent through routers in the packet network that independently determine the best path at the time that will help the packet reach its destination (smart switches). This diagram shows the three packets take 3 different routes to reach their destination. When the 3 packets reach their destination, the remote computer reassembles the data packets into the original data file.


Packet-switched Data

Public Data Networks (Internet)
Public data networks interconnect data communication devices (e.g. computers) with each other through a network that is accessible by many users (the pubic). To allow many different users to communicate with each other, standard communication messages and processes are used. The Internet is an example of a public data network (there are other public data networks) that uses standard Internet protocol (IP) to allow anyone to transfer data from point to point by using data packets. Each transmitted packet in the Internet finds its way through the network switching through nodes (computers). Each node in the Internet forwards received packets to another location (another node) that is closer to its destination. Each node contains routing tables that provide packet-forwarding information.

Each network in the Internet can have different transmission formats (e.g. different packet sizes, high-speed or low-speed data) but the all agree on how to receive and distribute IP packets. Internet service providers (ISPs) connect users (e.g. computers) to the Internet. ISPs are interconnected to each other through network service providers (NSP). NSPs are relatively large networks that may cross international boundaries. NSPs can connect to each other through network access points (NAPs). Because there are a limited number of NAPs, there are also private network access points (PNAPs). PNAPs are setup by the NSPs to relieve the congestion on the NAPs.

Figure below shows the Internet. This diagram shows that the Internet is composed of users (end points), Internet service providers (ISPs), network service providers (NSPs), and network access points (NAPs). Computers are connected to the Internet via an ISP. The ISP receives data from the computer, reformats it (if necessary), and forwards it to the destination computer in its network. If necessary, it may be routed to an NSP, which will route the data packets to their destination ISP to an NAP that will allow the packet to reach its destination. Eventually, packets reach their destination ISP that forwards the packets to the user.