Wireless Networks And WMAN Technology

The inner workings of IEEE 802.11a and 802.11b

Discuss about the Wireless Networks for OSI Communication Model.

The inner workings of the physical layer of the standards IEEE 802.11a and 802.11b

The physical layer is the lowest layer of the OSI communication model and it majorly is involved with the transmission of data across devices having different specification and operation parameters. In essence, it supports the transmission of signals across electrical and mechanical systems offering a means to transport the 802.11 frame in this instance (Pearson, 2017).

This standard offers a competitive alternative to wired communication where data is transferred across the electromagnetic spectrum. Now, as a wireless technology, the standard is characterized by the OFDM multiplexing technique that increases the bandwidth of transmission. In essence, OFDM (Orthogonal frequency division multiplexing) facilitates the diversification of the communication channel by splitting it based on the operational frequency (world, 2017). Nevertheless, its inner workings of the physical layer are as shown below:

• First, the layer operates with a 54 Mbps data rate that is supported by a 5 GHz frequency band.
• This operational band is then usually diversified by the OFDM technique which splits the transmission channel (radio spectrum) into 48 different subsections. These sections are then spread across the wider channel width of 20 MHz
• Now, following this separation, several data rates are offered to the users including; 6, 12 and 24 Mbps.
• Moreover, due to the variations in operational speeds, the standard applies other extended modulation techniques which supplement the original multiple access method. First, the binary phase shift keying (BPSK) is used for operations that fall within the 6 Mbps data rate. Secondly, quadrature amplitude modulation (QAM) is then used for functionalities having 54 Mbps data rates(Geier, 802.11a Physical Layer Revealed, 2003).

Another wireless standard that is an advancement of the original 802.11 standards having improved speeds and data rates. The 802.11b standard operates within a 300-meter distance range defining both the physical and MAC layer of communications (Primer, 2013). The inner workings of the physical layer:

• First, unlike the previous standard, its frequency band falls with the ISM range i.e. the Industrial, Scientific and Medical band. In the US this band falls between the frequencies of 2.4 and 2.4835 GHz, whereas in other countries such as Japan the range falls between 2.471 and 2.497 GHz.
• Furthermore, the bandwidth of operation is split into 14 subsequent channels of 22 MHz each. These subsequent bands overlap each other facilitating the exchange of information across different devices.
• In addition to this, the standard is characterized by a chip rate of 11MHz which facilitates the transmission of signals with the following rates; 1, 2, 5.5 and 11 Mbps.
• Finally, the standard uses the spread spectrum technique to multiplex signals i.e. the DSSS plus an addition of the complementary code key modulation (CCK)(Koivisto, 2006).

Attribute	802.11a	802.11b
Frequency band	5 GHz	2.4 GHz (ISM)
Data rates	6, 12, 24 Mbps	1, 2, 5.5 and 11 Mbps
Multiplexing technique	OFDM	DSSS
Modulation technique	BPSK and QAM	CCK

In general, the 802.11 standard is a specification for implementing wireless networks (WLANs) that defines both the media access control (MAC) and the physical layer. The original standard operated with a 900 MHz frequency band that extended to cover up to 60 GHz range. Moreover, the 802.11 standards used basic authentication and encryption techniques more so the WPA (WiFi protection access) and the WEP (wired equivalent privacy) (Chaplin, 2005). These standard were both weak and were easily cracked which led to the development of the 802.11i standard that operates with higher security standards including the application of the WPA2, which above its better authentication structure is supported by AES (advanced encryption standard).

Nevertheless, during the authentication of devices across networks (clients to servers) a robust and resilient procedure is followed through the application of a four-way handshake. This handshake operates with a group keying systems that involves three elements; the supplicant (client), the authentication server and the general authenticators (i.e. the relaying party) (Latour, 2012). Furthermore, the extensible authentication protocol (EAP) is usually the defining protocol for the 4-way handshake as outlined below (The process):

• First, the client sends a notification to the server in the of an EAP message.
• The access port then sends an EAP request to the authenticators in an attempt to relay communications.
• From here, the client’s EAP response from the server is followed by an encryption process of (proxied communication) with both the authenticator and server communications.
• The server then requests the client to identify itself by verifying its credentials.
• Now, depending on the client’s response, the server either accepts or rejects the connection request.
• In an accepted scenario, the virtual access port of the server is turned into an authorized state which grants the client access to the server.

To understand the usage of VPNs in establishing secure and encrypted connections, one must highlight their operational platform i.e. the internet. In all, the internet is a public infrastructure or environment that is populated with many networks. Now, although these networks maybe protected, users requiring secure connections cannot trust the existing channels of communication. Therefore, VPNs facilitate this functionality by creating private access channels that link different points across the public medium of the internet (MPR). Now, two general methods are followed:

• Remote access where parties located in remote areas access localized networks (LANs) using specific access portals.
• Site to site VPNs which are used on a larger scale having specific point to point connections across the internet. In this case, the connections are usually unique at each instance and are supported by specialized accounts.

IEEE 802.11i authentication

In terms of the techniques of operation, VPN uses a system of keys to authenticate the users accessing the established private networks. These keys can either by systematical where common keys are shared among the users or asymmetrical keys that require specialized authenticators to verify them (public-private keys) (Cisco, 2008). In addition to this, a number of encryption standards facilitate the operations of VPNs including IPsec which holds a wide range of authentication, encryption and integrity standards. Moreover, the GRE (generic routing encapsulation) protocol is also used to meet the same objectives.

To meet its customer’s ever-growing demands, ZeeTech a multinational company has established five different offices in Melbourne. These offices require a common connection to aid the company’s operations and services. Now, as a solution the company envisions a wireless metropolitan area network (WMAN) that could serve all the enterprise’s offices. This section analyses the different technologies that could meet this objective.

WMAN

WMAN serve as suitable substitutes for wired broadband connections that require extensive expenses owing to the installation of physical infrastructures such as copper cables and extensive switching cabinets (UOM, 2005). Moreover, in some applications WMANs serve as convenient backups in case the wired systems fail. In this scenario, the following WMAN technologies are proposed:

1. HiperMAN
2. HiperACCESS
3. WiMAX

This technology is one of the original standards of implementing WMAN for broadband connections. To start with, HiperMAN operates within the 2 to 11 GHz frequency range which facilitates the transmission of signals under the low frequencies. This frequency band has minimal penetration power which limits the amount of information transferred as well as the distance of operations. On the other hand, the standard also offers a medium sized data rate of 25 Mbit/s which when coupled with its optimal point to multipoint configuration increases the amount of information transmitted. However, to cater for higher rates and information quota, extra resources must be established which increases the overall expenditures. Furthermore, its security features are rudimentary as compared to those of the other two (works, 2017).

An interoperable and integrative standard that offers broadband connections to a wide range of wireless devices. Unlike HiperMAN, this technology supports the operation of mobile devices through the use of backhaul services such as GSM and GPRS. This functionality is welcomed in ZeeTech’s operations as they may require the different office to communicate via mobile systems. Furthermore, its connection offers a higher data rate of 100 Mbit/s which increases speeds of communication facilitating better services for the company. In addition to this, HiperACCESS uses a high-frequency band of 40.5 GHz which may be extended to about 43.5 GHz thus facilitate a wider coverage (WMICH, 2015). Now, the cost is minimal when compared to HiperMAN owing to its operational frequencies, however, when low frequencies are considered the technology balances out with its predecessor as additional resources are needed. However, it has better security features which include advanced access control systems.

VPNs for establishing secure and encrypted connections

The final technology considered for the company at hand that has better features and attributes as compared to the rest. Now, to start with, WiMAX operates within the IEEE 802.16 standard which among other functionalities, enhances the compatibility of wireless devices which boosts the integration wireless devices (IEEE, 2016). Furthermore, the technology offers both first and last mile connections serving at a high-frequency range of 66 GHz. This frequency band extends wireless broadband connections to distances of about 50 kilometres. This distance of operation would conveniently serve ZeeTech who on occasion may require field workers to perform their marketing operations. On the other hand, its data rates are better as compared to those discussed so far as they extend beyond the 100 Mbit/s mark to around 1 Gbit/s. Now, when this rate and frequency range are combined, the technology provides a bigger service area that other WMAN technology that cannot offer. Finally, in terms of the security features, WiMAX offers advanced authentication techniques such as the PKMv2 and over the air encryption which facilitates the maintenance of secure end to end connection.

In wireless communication, the transmission channel is usually confined within the limits of the radio spectrum. This limitation necessitates the need to diversify and spread the existing area through the multiplexing techniques. TDMA is one such technique that uses time allocations to assign bandwidth to the communicating users. In essence, the technique will divide the frequency of operation (bandwidth) into different sections based on a timing schematic (Fendelman, 2017). This separation process will result into different time slots that the communicating parties are assigned thus facilitating the transmission of multiple signals across common channels.

Attributes of TDMA:

• The technique uses time slots to assign the bandwidth of communication.
• Its functional data rate varies between 64 kbps and 120 Mbps.
• Moreover, it can adequately transmit both data and voice.
• Furthermore, its operations are based on the immediate needs of the users which optimize the battery life as its only activated when needed.
• Finally, its optimal for analogue to digital signal conversion owing to its minimal cost expenditures(Electronicdesign, 2017).

A similar technique to TDMA that usually aims to maximize the bandwidth of operations through the diversification of the radio spectrum. However, unlike TDMA that allocates space after dividing it into various frequency bands, CDMA assigns signals unique identification codes that facilitate the transmission of multiple signals under single communication channels. In essence, CDMA will not divide the bandwidth of communication and instead will assign signals pseudo-codes which will identify them to the transmitters and receivers (Fendelman, 2017). Therefore, each signal uses the entire bandwidth during transmission which optimizes the process, due to the overwhelming size of the channel’s capacity. Moreover, the pseudo-codes improves the security of the technique as they are uniquely identified by the users.

Attributes

• CDMA is a spread spectrum technique.
• It’s also convenient for both data and voice transmission.
• Furthermore, it facilitates a higher transmission capacity.
• Finally, it has good security features owing to the application of pseudo-codes(Segan, 2017).

An open digital and cellular technology that is used for wireless transmission of information through mobile devices. GSM supports both voice and data communication through a circuit switched technique. In essence, GSM uses a circuit switching to establish the network of communication before embarking on the transmission process. In addition to this, GSM also divides the overall channel of communication into smaller convenient sizes which facilitate the multiplexing process (Segan, 2017). In all, a 200 kHz bandwidth is divided among 8 different channels which result into communications slots of 25 kHz.

Attributes

• Similar to the other two, its operations support both data and voice transmission.
• It also has a wider frequency band.
• Finally, its characterized as a circuit switched technology(Rouse, 2017).

References

Chaplin, C. (2005). 802.11i Overview. Retrieved 02 October, 2017, from: https://ieee802.org/16/liaison/docs/80211-05_0123r1.pdf.

Electronicdesign. (2017). Fundamentals of Communications Access Technologies: FDMA, TDMA, CDMA, OFDMA, AND SDMA. Communications, Retrieved 02 October, 2017, from: https://www.electronicdesign.com/communications/fundamentals-communications-access-technologies-fdma-tdma-cdma-ofdma-and-sdma.

Fendelman, A. (2017). Cellphone Glossary: What Is GSM vs. EDGE vs. CDMA vs. TDMA? Life wire, Retrieved 02 October, 2017, from: https://www.lifewire.com/gsm-edge-cdma-tdma-578682.

MPR. (n.d.). Virtual Private Networks. VPN2, Retrieved 02 October, 2017, from: https://web.fe.up.pt/~mricardo/05_06/redesip/acetatos/vpnv2.pdf.

Pearson. (2017). IEEE 802.11 Physical Layers. Pearson, Retrieved 02 October, 2017, from: https://www.informit.com/articles/article.aspx?p=19825&seqNum=3.

Primer. (2013). Wi-Fi: Overview of the 802.11 Physical Layer and Transmitter Measurements. Retrieved 02 October, 2017, from: https://www.nortelcoelectronics.se/document-file5116?lcid=1053&pid=Native-ContentFile-File.

Rouse, M. (2017). GSM (Global System for Mobile communication). Retrieved 02 October, 2017, from: https://searchmobilecomputing.techtarget.com/definition/GSM.

Segan, S. (2017). CDMA vs. GSM: What’s the Difference? PC reviews , Retrieved 02 October, 2017, from: https://www.pcmag.com/article2/0,2817,2407896,00.asp.

world, R. w. (2017). Overview of 802.11a physical layer. Home of RF and Wireless Vendors and Resources, Retrieved 02 October, 2017, from: https://www.rfwireless-world.com/Articles/Overview_of_11a_PHY_layer.html.