NET 211 - Wireless Networking

Chapter 1, The World of Wireless; Chapter 2, Wireless Local Area Networks

Objectives:

This lesson presents background on wireless networks and begins discussion of Wireless LAN standards. Objectives important to this lesson:

  1. Wireless Applications
  2. Wireless: Advantages and Disadvantages
  3. Types of Wireless Networks (actually, sizes)
  4. Wireless technologies and LAN standards
  5. Standards Organizations and Regulatory Agencies

  6. Understanding Standards
  7. Common Wireless Standards
  8. Client Hardware and Software
  9. WLAN Infrastructure
Concepts:
Chapter 1

The chapter begins with a description of a disruptive technology as "an innovation that fills a new role that an existing device or technology could not". (Ciampa, page 2) The author gives us some examples of technologies that have supplanted other technologies, so his proposition seems to be that innovation replaces older technology when the innovation does something the older one did not, or does something better than the older one. The author is correct, but too sweeping in some of his assertions.

  • steamships - this technology replaced sailing ships as a better solution for commerce, but sails still exist for pleasure craft
  • telephones - this technology replaced telegraphy, which still exists, but telegrams are now sent over a different infrastructure, mostly by independent vendors
  • automobiles - this technology replaced commercial use of horse drawn vehicles in most places; Mackinac Island and Amish communities are examples of isolated exceptions to this; cars did not replace horses in general
  • word processors - this technology replaced typewriters as the default choice for business, where the supporting technology for word processors exists
Applications

As I have noted about word processing, if the supporting technological infrastructure for a given invention is not common, that invention will not become a common technology. Most of the readers of our text live in the midst of technology, but the whole world does not, so let's accept some of Mr. Ciampa's assertions with a little reluctance. They will not all be true for everyone.

The author spends about ten pages discussing uses to which wireless technology has been applied in several different occupations and industries.

  • education - generic recommendations are made about easy connection to networks and resources for teachers and students
  • business - the ability to access the network from any location in your building is noted, whether the user is moving to a new office/cubicle, having lunch, or going to a meeting
  • construction - mobile record keeping and updating, location management with GPS (Global Positioning System) equipment, and project management are mentioned
  • warehouse management - management of inventory with RFID (Radio Frequency Identification) tags and management software are discussed
  • manufacturing - RFID management of raw and finished materials is mentioned
  • travel - wireless communication for travelers and for people running travel services is mentioned
  • public safety - wireless access to data networks for police and fire personnel is mentioned, as well as communication between all levels in their organizations
  • health care - immediate wireless update for patient information and doctors' orders is mentioned

The text continues to discuss advantages and disadvantages inherent in wireless systems:

Advantages
  • mobility - users can use a network without having to be close to an available wired connection point
  • access - connection to networks can be offered where it is not practical to run wires; the text mentions that some cities offer municipal networks, systems of hot spot connections to a network service run by the city
  • connectivity - connection to ISPs (Internet Service Providers) may not be possible for some remote users unless they use a wireless solution such as data services from a cell phone company; wired or fiber connections between locations for companies in highly populated areas may be much more expensive than wireless solutions due to the cost of digging and laying cable in densely populated urban areas
  • deployment - network cable is a common construction standard now, but older buildings never had it, making wireless solutions the easiest to deploy; the author is ignoring the fact that someone has to have a connection to a wired network that the Wireless Access Points (WAPs) can use as their connection to the rest of the world (This is really the same problem as connectivity. It is simply expressed from the point of view of the Local Area Network manager.)
Disadvantages
  • security issues - the author presents several bullets that need expansion: wireless transmissions can be intercepted; wireless networks can be easier to join and attack; employees have been known to add their own WAPs to networks, which they typically do not protect against intrusion; older wireless security protocols are well known and no longer secure
  • radio signal interference - often called radio frequency interference (RFI), this is when your wireless signals are disrupted by any nearby device that transmits radio signals on a similar frequency to the one you are using
  • range of coverage - this one proves that the author needs a proofreader: ten feet is about 3 meters, not 33 meters, and that is a common limitation on Bluetooth signals; other technologies have longer ranges, but all are shorter than a standard network cable can be run; some Bluetooth systems can work at a distance of 10 meters (about 33 feet)
  • slow speed - the author means narrow bandwidth; the number of bits we can push through a network in a given time interval will be greater in a wired network than in a wireless network, if we are given a choice of which to use

Types of wireless networks are discussed next, but the author is merely classifying them according to the relative size of the area they serve, not by their technologies. As the author mentions at the end of this section, the designations below can overlap, and they are only rough designations, not true measures.

  • Wireless Personal Area Network (WPAN) - very short range methods are used for one person to connect to their own devices
  • Wireless Local Area Network (WLAN) - the author hints at a reality we should accept, that a wireless LAN is often a supplement to a wired LAN: this is true of the rest of these designations as well; the range and throughput measures mentioned in the text vary with the wireless protocols being used and with each location, due to signal interference and blockage; typical coverage is within one building
  • Wireless Metropolitan Area Network (WMAN) - meant to cover several blocks or a small city, this is actually a series of WLANs that are linked together with longer range technologies or standard ones
  • Wireless Wide Area Network (WWAN) - the example in the text is of a user connecting to the Internet by attaching a cellular wireless data connection device, which the text calls a 4G (Fourth Generation) cellular device and a Long Term Evolution (LTE). This type of connection is limited in use to areas serviced by cellular data providers. They typically only provide service in larger metropolitan areas.
Wireless Standards

The text lists five organizations whose job is to either create, define, and standardize methods for making networks and wireless products work, or to regulate how people comply with legal regulations about such standards.

  • International Telecommunication Union Radio Communication Sector (ITU-R) - a body whose regulations are meant to be followed by manufacturers in all countries; it is mainly concerned with managing the use of any part of the electromagnetic spectrum
  • Federal Communications Commission (FCC) - an agency of the United States federal government that regulates the transmission of electronic signals, wirelessly or on cable media; primarily concerned with the spectrum portions used by television, radio, satellite, and cable signal providers
  • International Organization for Standardization (ISO) - a multinational trade association composed of delegates from standards organizations from various countries; it is concerned with many kinds of activities, including wireless activities
  • Institute of Electrical and Electronic Engineers (IEEE) - the organization responsible for most of our networking standards including those for wireless operations; the text mentions several IEEE standards: IEEE 802.3 (commonly called the Ethernet standard), IEEE 802.5 (Token Ring standard), 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac (multiple standards for wireless networking), and IEEE 802.15.1 (Bluetooth).
    The graphic on page 24 depicts the progression of a proposed standard from an IEEE Study Group, to a Task Group, to a Work Group, to a proposal to amend the existing standards, to a published standard.
  • WI-FI Alliance  - another trade association that checks devices for compliance with various standards
Chapter 2

Chapter 2 continues the discussion of standards by making it clear that an industry that depends on equipment and software that must operate cooperatively must have standards for such cooperation to happen.

  • Standards allow interoperability between software and hardware from different vendors
  • Standards create competition between vendors when they know you are free to change to a product from a competitor. This can lead to lower costs for products and services.
  • Standards can protect you from buying proprietary technology that is no longer supported by a vendor

The text lists three kinds of standards that you may encounter:

  • de facto standards are really just common practices, or commonly used technology
  • de jure standards are established by an organization empowered to create and enforce some kind of standard
  • consortium created standards are established by common agreement among practitioners who participate in formal discussions and adoption of standards

The text moves on to discuss Wireless LAN standards. It presents a list of various IEEE standards and the years they were adopted. The four shown in bold below are  the ones that have dominated the field.

  • IEEE 802.11, 1999
  • IEEE 802.11a, 1999
  • IEEE 802.11b, 1999
  • IEEE 802.11d, 2001
  • IEEE 802.11g, 2003
  • IEEE 802.11h, 2003
  • IEEE 802.11i, 2004
  • IEEE 802.11j, 2004
  • IEEE 802.11e, 2005

There have been other standards since these, notably IEEE 802.11n (2009) and IEEE 802.11ac. The text discusses some of them in more detail.

  • 802.11 - Described how a wireless LAN might be implemented using either radio waves or some form of light that humans cannot perceive. Only provided bandwidths of 1 or 2 Mbps.
  • 802.11b - Added technology to increase bandwidth to 5.5 or 11 Mbps, and to allow devices to be up to 350 feet apart. When stations are located increasingly farther apart, the bandwidth between those stations is dropped down to lower levels.
  • 802.11a - This standard supports data rates of 54, 48, 36, 24, 18,12, 9, and 6 Mbps. Sounds great, but its effective range was much less. The text states that devices could be no more than 100 feet apart.
  • 802.11g - This standard included the best features of the 802.11a and 802.11b standards. It offered the bandwidth selections of the 802.11a standard, and the range of the 802.11b standard.
  • 802.11n - This standard provided the potential of using two frequencies at once to increase throughput up to 600 Mbps. Range was supposed to increase, but the IEEE only reports the same effective range as 802.11g.

frequency
channels, channel bandwidth
data throughput range
802.11a
5 GHz band
52, 23 not overlapping, 20 MHz each
up to 54 Mbps 25-75 feet
802.11b
2.4 GHz band
14, 3 not overlapping, 22 MHz each
up to 11 Mbps
100-150 feet
802.11g
2.4 GHz band 14, 3 not overlapping, 22 MHz each 54 Mbps 100-150 feet
802.11n
2.4 or 5 GHz bands, or both with multiple antennas 14, 3 not overlapping, 20 or 40 MHz each
65 to 600 Mbps 100-150 feet
802.11ac
5 GHz band 5, up to 80 MHz wide
78 Mbps to 433 Mbps/data stream
TBD

The text changes topics to discuss hardware and software used in wireless LANs. Its first topic is wireless connection devices.

  • Wireless Network Interface Cards (Wireless NICs) - The text explains that a typical wireless NIC works like a regular NIC, but it also includes a radio and antenna (which may be hidden from the user) that typically communicate with a Wireless Access Point which is connected to a standard LAN. A wireless NIC may plug into a standard bus slot in a motherboard, it may incorporated in the motherboard itself, or it may plug into a USB port or a PC Card socket.
  • Wireless Client Software - Software must be used to interface bettween the standard network signals that the computer would send (on a wired Ethernet, for example) and the drivers for the wireless NIC. It may be part of the operating system, such as WLAN Autoconfig found in Windows Vista and Windows 7.

The text continues with a discussion of commonly used wireless infrastructure devices, which are used at the periphery and inside networks.

  • Access Points (APs) - also called Wireless Access Points (WAPs); these devices are the interfaces between wireless devices and a network; they connect to a wired network like any other device, but they act like switches through which wireless devices gain access to the wired LAN; typically, they have three components:
    • one or more antennas and one or more radio transceivers, depending on the standard being used
    • software to connect devices attached to the network of the WAP to each other; devices that join the WAP's network are assigned IP addresses from the WAP
    • a network port to connect the WAP to a wired network, bridging the two networks
  • Autonomous Access Points - these are access points that also perform encryption and authentication; these devices maintain their own autonomous network that connects to the wired network, which means that these devices are more like routers than like switches, and that they will assign station IDs to the connecting wireless devices
  • Lightweight Access Points - these APs are like a halfway step between Access Points (which are actually lighter) and Autonomous Access Points; these devices coordinate the connection of wireless devices to the network; their actions are not autonomous, they are managed through a wireless LAN controller which does the actual coordination
  • Mesh Access Points (MAPs) - This concept addresses a problem the previous examples share. If every version of an access point (lower case, generic term) has to be connected to a LAN, this becomes a problem if you don't have LAN jacks everywhere you want an AP, such as at a county fairground. A Mesh Access Point is part of a wireless mesh network (WMN): each MAP connects to other MAPs that are in range, and only one of them has to be connected to a wire LAN for all of them to have access to it. The text refers to the connections from one MAP to another as a hop, which is the same term used to describe a connection from one router to another. The MAPs are essentially cell towers in a small cell network.

    The text also mentions another kind of WMN that does not use MAPs. It is talking about a collection of wireless clients that pass signals from one to another more like a peer to peer network. This is called an ad hoc wireless mesh network.
  • WLAN Bridges - As the text explains, a bridge is a device that connects two network segments, which can improve network performance by isolating traffic to one side of the bridge or the other. A wireless bridge makes a wireless connection between two network segments. The text describes two types. A wireless workgroup bridge connects two network segments that are a short distance apart. A remote wireless bridge is more powerful and can be used to connect network segments that are separated by greater distances.
  • Gateways - devices that serve as entry or exit points for a network
    • Enterprise Encryption Gateways (EEGs) - sits between a wired network and a wireless network; its purpose is to do the encryption and authentication services that a regular AP cannot do
    • Residential WLAN Gateways - this is the device that Comcast or Time Warner or another cable provider placed in your house if you use one of them as your ISP; this device provides wireless access, firewall service, routing, switching, and DHCP service to a residential customer
  • Power over Ethernet (PoE) Devices - devices that are equipped to receive their operating power through a UTP Ethernet cable (DC) instead of through a standard AC power cord; this technology requires a means of supplying DC power through the Ethernet cable, which is commonly achieved by using PoE Enabled Ethernet Switches

Assignment 1: Chapter 1 and Chapter 2

  1. Review Questions from Chapter 1, 1 - 20
  2. Review Questions from Chapter 2, 1 - 10
  3. Hands-on projects assigned in class