Wireless

NTC/360 r4 Network & Telecommunications Concepts

John H. P. Ho

October 17, 2005

Wireless Technology

There will always be the need for hard wires, backbones and fiber connections, but the day of having to use a BNC or RJ-45 connector as the only way for a computer or device to get connected to a network is long gone. Welcome to the world of wireless. Everyone today wants to use wireless, from keyboards, to TV remote control, Xbox game controllers, cell phones, cell phone ear buds and of course the coffee shop laptop users. This paper is going to highlight some of the technologies associated with the IEEE standard of 802.11, some security measures to be considered, how it applies in the corporate world and some future enhancements of this technology.

Wireless Technologies / Types

There are several different specifications in regards to wireless networking. The Institute of Electrical and Electronics Engineers (IEEE) developed the 802.11 standards for the wireless networking group. There are the 802.11, 802.11a, 802.11b, and 802.11g. On the near horizon is the 802.11n specifications that will be pushing 200+ Mbps over the air (Deviceforge.com, 2005). The larger 802 specifications focus on the physical and data link layers of the OSI model since all 802 networks include a physical component and a media access control (MAC). Examples of other specifications under 802 include 1, 2, 5, and 11 among others. The 802.s specification describes a common link layer and the logical link control (LLC). 802.11 like the 802.2 specification includes LLC encapsulation. 802.11 further includes MAC, frequency hopping spread spectrum (FHSS), and direct sequence spread spectrum (DSSS). In the narrow-band or single-frequency radio LAN's the receiver and transmitter use the same specific frequency for incoming and outgoing data to a maximum range of 70 meters. Spread-spectrum radio offers advantages over single-frequency in that it uses several frequencies simultaneously, which improves reliability and reducing possible interference. The two types of spread-spectrum include frequency hopping and direct-sequence modulation. Frequency hopping switches the frequencies it uses at a regular interval for data transfer with speeds of up to 2 megabits per second (Mbps). Direct-sequence modulation splits data into segments and transfers the data simultaneously among different frequencies with speeds up to 6 Mpbs. All of these different specifications under 802 are to allow and describe different capabilities of the specification such as 802.5's token ring support.

802.11

802.11 also known as 802.11 legacy was released in 1997 and has speeds up to 2 Mbps. Because this speed was too slow for most network applications it was easily replaced by faster specifications.

802.11a

802.11a, created at the same time as 802.11b, was developed primarily for commercial business due to its higher cost for hardware. 802.11a supports speeds of up to 54 Mpbs although this specification uses high carrier frequencies (regulated 5 GHz range) which means that there is less interference, but limits connections to line of sight because the higher carrier signals have much more difficultly penetrating walls and obstructions.

802.11b

802.11b supports speeds up to 11 Mbps. 802.11b although created at the same time as 802.11a was popularized more quickly because of the cheaper cost of equipment and lower frequencies that it used. 802.11b uses the same 2.4 Ghz range frequencies that the original 802.11 standard used which can be interfered with more easily from microwave ovens, cordless phones, and other equipment using the same frequencies. Although these lower frequencies penetrate walls and other obstructions more easily.

802.11g

The next advancement in the 802.11 family of WLAN that emerged in June of 2003 is the 802.11g standard. This standard is an extension of the 802.11b standard with improved transmission speeds up to 54 Mbps. The 802.11g wireless cards can talk to a 802.11b wireless access point by connecting at the lower 11 Mbps speed because of the backward compatibility that is built into this standard. The same is true for a 802.11b enabled device connecting to a 802.11g wireless access point, but of course it will not be able to use the full 54 Mbps available to it. The frequency band used by the 802.11g standard is at 2.4 GHz and falls into the same issues that the 802.11b family has and that is interference with other wireless devices around the home or business like cordless telephones, microwave ovens or other electronics that use that frequency range.

Wireless Speeds

The 802.11 speeds have continues to increase in speed and reliability. Here is a table taken from DeviceForge.com (2005) showing the different speeds for the 802.11 standards.

Wireless LAN Throughput by IEEE Standard

IEEE WLAN Standard Over-the-Air (OTA) Estimates Media Access Control Layer, Service Access Point (MAC SAP) Estimates

802.11b 11 Mbps 5 Mbps

802.11g 54 Mbps 25 Mbps (when .11b is not present)

802.11a 54 Mbps 25 Mbps

802.11n 200+ Mbps 100 Mbps

Table 1. Comparison of different 802.11 transfer rates. (Source: Intel Labs)

Wireless Security Types

There are no un-hackable security measures that will single handedly prevent hackers from stealing or taking over a network. With this said there are measures that can be put in place to make a wireless network not looking as attractive and hackers would most likely look else where for an easier mark. Another way of stating this would be living in a home that has no outside lights, living in a wooded area that obscure the view of a home, having now security alarms installed. To a crook this a like taking candy from a baby but on the other hand having flood lights installed a clear view of the home, lights that come on when movement is sensed and installing a alarm system. Even though this is still not 100% secure this will in turn deter the common criminal from picking this house and would most likely move on to a house that is an easier target of opportunity.

The best method to securing a wireless network would be add layers of security measure as more layers are added that chances for a hacker of getting caught