Channel Reuse And Frequency Reuse In Wireless Communication; ZigBee Transmitter And IoT Wireless Devices

MITS5003-Discussion on the Wireless Networking Concepts

Channel reuse in WLAN

1.Channel reuse in WLAN

Channel reuse in WLAN helps in increasing the capacity as well as the performance of the channel. When two radio transmitters use same frequency, then co-channel interference takes place (Zhu & Wang, 2012). Sometimes some access points are able to hear other access points (APs) on the same medium or channel then co-channel interference occurs. Co-channel interference can reduce the usage of channels. The throughput of the channels gets affected in an adverse manner as the other clients and APs would have to wait for transmitting their data.

Channel reuse helps to avoid co-channel interference and maximize the throughput of the channel (Jamil, Cariou & Helard, 2014). Dynamic control over receive sensitivity can be enabled by channel reuse for improving the spatial reuse of channels (Matsumura et al., 2012). Channel reuse designs are based on multi-channel architecture. The features of channel reuse are configured for operating in one of the three modes: static, disable and dynamic mode. The modes of channel reuse can be configured via 802.11g or 802.11a radio profile (Bellalta, 2016). Depending on the transmission power-level that is configured on the access point, the CCA or Clear Channel Assessment can be adjusted in the static mode. In the static mode, with the increase in CCA threshold, the power of the AP transmits decreases and vice versa. In the dynamic mode, the CCA thresholds are completely dependent on the channel loads. The feature of the dynamic mode gets enabled in an automatic manner when the wireless channel or medium surrounding the access point is busy for more than half of the time. In this case, the CCA threshold gets adjusted for accommodating transmissions between the access point and the distant client. The CCA detect threshold does not get tuned in the disable mode of the channel reuse.

 

Fig 1: Channel Reuse in WLAN

(Source: Jamil, Cariou & Helard, 2014, p. 305 )

Frequency reuse in Mobile Phone networks

In mobile phone networks, frequencies are allocated to different services and reused by following a regular pattern of the areas known as cells (Novlan et al., 2012). All the cells are covered by a base station. These cells are hexagonal and arranged in such a manner so that adjacent cells do not have same frequencies (Ghosh et al., 2012). The frequencies of the cells can be reused in an effective manner if the same frequency cells are not adjacent to each other. A typical plan of frequency reuse utilizes seven different frequencies in the hexagonal cells. In wireless communication the area that is needed to be covered are divided into several cells having different frequencies for avoiding interference and facilitating reuse of the radio frequencies (Zhang et al., 2013). Frequency reuse facilitates effective communication within a single cell and enables the re-use of frequencies in the nearby cells. Frequency reuse enables the use of same frequencies for carrying out multiple conversations (Feng et al., 2014). Consider a situation where N number of cells use same number of frequencies and K is the total number of frequencies. Then the cell frequency of each cell is given by K/N. Suppose K=397, N= 7. Then each cell frequencies will be 395/7=56. Frequency reuse helps in utilizing radio frequencies that are same within an area and separated by a certain distance. It helps in the increase of capacity.

Frequency reuse in Mobile Phone networks

 

Fig 2: Frequency Reuse

(Source: Novlan et al., 2012, p. 2033)

2.WMAN or Wireless Metropolitan Area Network helps in establishing wireless connections between various locations in a metropolitan area. Its area coverage is more than that of WLAN but less than that of WWAN (Jia, Cao & Liang, 2015).  One of the best known WMAN technologies is WiMAX. It has several benefits that can be utilized for improving the WMAN. Security challenges of WiMAX are:

1) Authentication related threats: Masquerading attacks can take place where one system masquerades its identity by reprogramming its hardware address with another device’s hardware address (Sari & Rahnama, 2013). Attacks can also take place on PKM protocol where the attacker saves the messages received from a legal subscriber station and performs replay attacks against the base station (Dubey & Kumar, 2013). The process of authorization has several vulnerabilities as it does not have any mechanism for ensuring message integrity.

2) Jamming attacks: In this type of attack a strong source of noise is introduced for reducing the capacity of the channel (Dubey & Kumar, 2013). This can take place unintentionally as well as intentionally. Jamming attacks can be easily performed by an attacker. This security challenge takes place in the physical layer. 

3) Denial of Service attack: Several types of DoS attacks such as unencrypted management of communication and unprotected entry in the network can take place in WiMAX technologies (Dadhich, Narang & Yadav, 2012). When a subscriber station sends several false requests of authorization to a base station, then the base station uses all the resources by carrying out calculations for checking the validity of the certificate (Sari & Rahnama, 2013). This will lead to a DoS attack as the base stations will be unable to serve the subscriber stations any further. In DoS attack, an attacker forges the RNG-RSP or Ranging Request/Response message for minimizing the power of the subscriber stations or SS and does not allow the SS to transmit to the base stations. DoS attacks can also be based on FPC or Fast Power Control, Authorization-invalid and Reset Command or RES-CMD message.

WMAN can use Wi-Fi technology. Wi-Fi technology has several security challenges. Data interception can take place when the eavesdroppers capture data over the Wi-Fi network (Banerji & Chowdhury, 2013). DoS attacks are the most common type of attack where the resources of the base stations are overused and it is unable to serve to the subscriber stations (Dondyk, Rivera & Zou, 2013). Wireless intruders and misconfigured access points are some of the major security challenges of the Wi-Fi challenges. Man-in-the-middle is a type of wireless phishing attack that can harm the Wi-Fi network.   

Wireless Metropolitan Area Network

3.Paper 1: Design and Simulation of State-of-Art ZigBee Transmitter for IoT Wireless Devices

This research paper discusses about the designing and simulation of ZigBee transmitter for the wireless devices of Internet of Things. Over the past few years, wireless networks have developed by providing extreme speed and higher range of applications (Elarabi, Deep & Rai, 2015).  The demand for high speed has increased everyday and this demand has led to the technology of ZigBee. This particular technology is an important standard of WPAN or Wireless Personal Area Networks.

The main advantages of ZigBee technology include lower rate of data and cost effectiveness. Moreover, the battery life is much more than the rest of the wireless networks. It defines a significant set of protocols related to communication. The range of frequency bands within which ZigBee normally operates is 868 MegaHz, 915 MegaHz and 2.4 GigaHz. The highest rate of data for the ZigBee technology is 250KB per second (Elarabi, Deep & Rai, 2015). There are various blocks of architecture in one digital ZigBee transmitter. This technology was developed due to the advancement of VLSI technology. ZigBee transmitter is extremely efficient, rapid and accurate. It never gives inaccurate data. Furthermore, ZigBee transmitter is smaller in size, which reduces the bulkiness of a device. 

IoT or Internet of Things is the networking of various physical devices or any other item that is implanted with sensors, software and even connectivity of various networks. The Internet of Things allows each and every object to link and exchange information within each other (Elarabi, Deep & Rai, 2015). Every device or item that is connected or linked to the IoT can be identified uniquely with the help of the implanted system of computing. However, they have the ability to internally operate in the infrastructure of Internet that already exists. There is an immense connection between Internet of Things and ZigBee technology. This technology is an application of Internet of Things or IoT as it allows lower rate of data and lesser power. The ZigBee transmitter can be easily designed with the help of Verilog for the applications of Internet of Things (Elarabi, Deep & Rai, 2015). A typical ZigBee transmitter comprises of a modulator, blocks of bit to symbol and symbol to chip and CRC or cyclic redundancy check.

Paper 2: From Today’s Intranet of Things to a Future Internet of Things: A Wireless and Mobility Related View

ZigBee Transmitter for IoT Wireless Devices

This research paper discusses about the evolution of Intranet of Things to Internet of Things. Intranet of Things is a specific element of all the encompassing IoT or Internet of Things (Zorzi et al., 2010). It utilizes same technologies or systems, however restricts to the access of all the connected or linked things to any corporate network.

The concept of Intranet of Things mainly comprises of every corporate asset that are accessible in any particular organization. However, these things can be accessed directly on the public Internet. Intranet of Things is somewhat too similar to the Internet of Things (Zorzi et al., 2010). IoT mainly harnesses sensor data, incorporates technology of big data and even machine learning. The machine to machine or M2M communication technology is also harnessed with the help of Internet of Things. 

There are various technological challenges that are related to the wireless and mobility related view of the evolution. Moreover, there are various methods for solving the procedure of challenges, faced while the Internet of Things is developed.

The architectural framework of the evolution of Intranet of Things to Internet of Things completely makes it possible for overcoming the present fragmentation and even the restriction of all the solutions (Zorzi et al., 2010). These restrictions occur where several Intranets of Things are present, in the direction of a real Internet of Things, where each and every device would be a specific part of a universally integrated system. 

Internet of Things first came into account ten years ago. Prior to it, Intranet of Things was ruling the market of wireless networking (Zorzi et al., 2010). The development was done with the help of RFID or Radio Frequency Identification and sensor networks. The sensor networks, which are considered to be an important pillar of the Internet of Things, have experienced various developments in recent years. A number of researches have been done on this development in the past couple of years, not only within the main area of the networking protocols, involving the routing and MAC, but also within the area of technologies like nano and micro, as well as on the problems in higher layer, like the applications, middleware and security (Zorzi et al., 2010). In future, the integration of RFID and sensor networks is supposed to bring exclusive development in the evolution of Intranet of Things to Internet of Things 

References

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Dondyk, E., Rivera, L., & Zou, C. C. (2013). Wi–Fi access denial of service attack to smartphones. International Journal of Security and Networks, 8(3), 117-129.

Dubey, S., & Kumar, S. (2013). Security Issues in WiMAX: A Critical Review. International Journal of Information and Computation Technology, 3(3), 189-194.

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