A Technical Comparison of Standards IEEE 802.11n and 802.11ac

Table of Contents

Abstract

A Technical Comparison of Standards IEEE 802.11n and 802.11ac

References

Abstract

Wi-fi is a commonly used wireless networking technology synonymous with the IEEE 802.11x standard group. The objective of this assignment is to evaluate two IEEE 802.11 technologies – 802.11n and 802.11ac – utilizing a variety of deployment factors. Furthermore, the impact of both 802.11n and 802.11ac in regard to wireless mesh networking deployment will be discussed. Although the IEEE 802.11 has continued to evolve with versions surpassing both 802.11n and 802.11ac, this paper solely focuses on these two with a brief mention of earlier, obsolete forms. With the release of 802.11ac following that of 802.11n, it is determined that 802.11ac offers overall better performance than that of its predecessor, albeit 802.11n is still in reduced existence due to its lower price point. The performance was measured through assessment of elements including throughput, data rate, frequency, and range, amongst others. A similar conclusion was drawn in that 802.11ac is better suited for deployment in wireless mesh networks, namely due to the advantages that it provides over the older 802.11n version.

 A Technical Comparison of Standards IEEE 802.11n and 802.11ac

Over the past decade, there has been an increasing shift towards workplace mobility or moving from the operation on a traditional wired network to the incorporation of a wireless network in some, or all, facets of a business. With the presence of WLANs (wireless local area networks) becoming progressively common, a set of standards was required to ensure that various wireless technologies could communicate with one another. As a result, the IEEE 802.11 standard, colloquially referred to as Wi-Fi, was created. IEEE 802.11 is the physical layer protocol that manages the transmission of information over air, typically between a wireless access point and wi-fi enabled device. WLAN networks provide tremendous convenience, thus continue to grow in popularity with a large demand in both commercial and residential environments. Since its conception, the 802.11 protocol has evolved into at least six separate versions, most of which have since become obsolete (Fitzgerald, Dennis, & Durcikova, 2015). IEEE technologies 802.11n and 802.11ac are two of the more recent of these protocol iterations. Performance comparison of 802.11n and 802.11ac displays their likenesses and differences while also establishing each’s impact when deploying wireless mesh networks.

IEEE 802.11n, introduced in early 2007 (Kelly, 2014), was the wireless standard set to improve upon the previously existing standards 802.11a, 802.11b, and 802.11g. Version 802.11n sought to provide users increased Wi-Fi network speeds as the transfer of video data became more prevalent in wireless LANs. Although rendered obsolete by many, some organizations still utilize this Wi-Fi version due to its low cost (Fitzgerald, Dennis, & Durcikova, 2015). IEEE 802.11ac, finalized in 2013, is the current “latest and greatest” of common wireless LAN protocols. It is important to note, however, that as of recent, 802.11ax may soon claim this title (Kerravala, 2018). 802.11ac provides even higher data rates than that of 802.11n as well as a much better signal range. In many ways, 802.11ac is comparable to wired connections (Mitchell, 2019). Both standards 802.11n and 802.11ac offer advantages over their predecessors, but most professionals would deem 802.11ac superior between the two. Furthermore, 802.11ac is backward compatible with previous standards, although optimal performance is seen only between devices both using 802.11ac.

A major reason for forming new Wi-Fi standards is the desire to maximize network speed, or data rate. The data rate is the speed at which data is transmitted between devices in a network and is measured in either megabit per second (Mbps) of megabytes per second (MBps). Theoretically, standard 802.11n reports a data rate of 450 Mbps while 802.11ac has documented speeds capable of nearly three times that of 802.11n at 1300 Mbps (Kelly, 2014). It is important to specify that these theoretical numbers are those of speeds achieved under perfect conditions, not the typical data rate that users can expect in daily activities. In reality, standard 802.11n generally registers a maximum data rate closer to 240 Mbps, and 802.11ac records top speeds nearing 720 Mbps. Although the actual and theoretical data rates differ quite a bit, the ratio for the two is nearly identical in that users can expect networks speeds to be three times greater when choosing 802.11ac over 802.11n.

Another important distinguishing factor between 802.11n and 802.11ac is the range that the wireless signals can travel. Before understanding range, however, it is important to note the role frequencies play in both standards. Standard 802.11n offers two frequency bands: 5 GHz and 2.4 GHz. For this reason, 802.11n is often referred to as being dual-band. On the contrary, standard 802.11ac only offers a frequency band of 5 GHz. This larger band is necessary to handle the increased speed that the 802.11ac standard offers. Additionally, the 2.4 GHz band is often crowded and prone to high interference levels (Estrada, 2013). Higher bands are not in all ways better, however. Operating at a higher frequency band means that even though network speeds are faster, the distance in which the data travels (or the range) is shorter and it can have difficulty maneuvering around physical obstructions such as walls. For this reason, the transmission ranges of both standards are comparable to about 100 meters under optimal conditions (Fitzgerald, Dennis, & Durcikova, 2015). Despite the similarity in range, what sets the 802.11ac standard apart is that it still transmits at much faster speeds than the 802.11n standard, thus, communication at the far end of the transmission range occurs quicker when using 802.11ac. Even though 802.11n offers a lower frequency band that enables a farther potential transmission range of maximum 300 meters, it still often suffers from overcrowding and high rates of interference, heavily impeding optimal performance and mitigating the advantages associated with a farther range.

The ability to operate at a higher frequency band enables both standards 802.11n and 802.11ac to have higher throughput values. This is because the 5 GHz band is less crowded and has less interference, thus more error-free information bits are received per second. The 802.11n standard further increases its throughput with the use of channel bonding or transmitting data simultaneously over two non-intersecting channels. This enables users to transmit multiple streams of data at one time (Sangolli & Jayavignesh, 2015). The maximum throughput for 802.11n running on the 2.4 GHz band or the 5 GHz is approximately 450 Mbps, although under non-ideal conditions is closer to 100 Mbps. If both bands are used simultaneously, the maximum throughput is increased to nearly 600 Mbps under ideal circumstances or 125 Mbps if not (Vaughan-Nichols, 2010). This requires particular dual-band 802.11n equipment. Standard 802.11ac offers faster data rate speeds than that of 802.11n, hence it also offers a higher throughput value. In an ideal situation, the maximum throughput for 802.11ac would be 1300 Mbps, or equivalent to the data rate. Since throughput takes into account outside factors such as retransmission and overhead bits, this value is not realistic. It is more likely that the maximum actual throughput will be measured at a maximum value of 50% of the data rate speed.

Another important differentiator between 802.11n and 802.11ac is their employment of antennas. Antennas are used for communication between devices. The more antennas a device has, the more separate data streams it can send and receive which increases both data rate and throughput. Both 802.11n and 802.11ac are considered to provision MIMO (multiple input/multiple output) configurations, or they support multiple antennas (Sangolli & Jayavignesh, 2015). Standard 802.11n supports up to four antennas, each supporting a maximum data rate of 100 Mbps. 802.11ac, however, has the ability to support up to eight antennas. This being said, the fastest routers still only support four antennas (Kelly, 2014). Antennas take up physical space on the devices with each sending and receiving separate data streams. On current routers, four antennas provide the maximum speed without having too little physical space on the router itself as well as ensuring the antenna locations are not so close together that their signals begin to interfere with one another.

For wireless protocols, it is best to place the core router in a central location, especially for routers utilizing 802.11n. This is because of signal propagation. Wireless signals allow for transmission within a certain radius of the router or access point. 802.11n offers a dual-band network and three separate channels (Fitzgerald, Dennis, & Durcikova, 2015), providing not only faster data rates but the ability to stretch the network out a bit farther. The three channels allow for access points to be spread where needed, so long as channels with the same frequency do not overlap. Furthermore, 802.11n uses multipath signals for signal propagation by way of multiple antennas. For example, a centralized router can have its different antennas positioned in separate directions to optimize signal reception in as many directions as possible. Regardless, it is still best to place a router in a central location for an optimized signal. The same signal propagation concepts apply for 802.11ac Wi-fi. An optimized signal can be achieved with a central router and the orientation of antennas in various directions. 802.11ac adds an additional aspect to signal propagation in the use of beamforming (Kelly, 2014). Beamforming is a “smart signal” aspect that detects the general area of connected and active devices and strengthens the signal in that direction. Wireless propagation for both wireless technologies is not faultless, however. Wireless propagation issues arise in many different forms. One issue is electromagnetic interference which is the result of devices transmitting on the same frequencies. Both 802.11n and 802.11ac attempt to mitigate this issue by using multiple channels and positioning the antennas in different directions. Another signal propagation issue is the presence of dead zones or locations where the signal path is obstructed by a physical object. Dead zones worsen at higher frequencies, presenting an issue primarily for 802.11ac as it only operates at the 5 GHz frequency band. Attenuation is another signal propagation issue that increases as the signal moves farther away from its originating source. Attenuation issues are also more prevalent at higher frequencies (Kassner, 2013). Both dead zones and attenuation issues can be lessened by strategic placement of access points or of the router itself. Both 802.11n and 802.11ac are not immune to signal propagation issues, but practical steps can be taken to alleviate these problems.

An alternative to traditional wireless infrastructures is the concept of wireless mesh networks (Roos, 2019). Wireless mesh networks have the ability to easily and effectively connect large areas with the use of wireless mesh nodes that all share the network connections. What primarily differentiates wireless mesh networks from traditional mesh networks is that they require only one node – typically a Wi-Fi access point – to be physically wired to the originating network. This physical node then connects to other non-wired nodes throughout the deployment area (Froehlich, 2017). These nodes utilize dynamic routing to transmit data across the quickest path. There are several advantages of wireless mesh networks aside from the decreased capital involved wiring, including ease of installation, convenience, and lack of need for a line of sight for functionality (Roos, 2019).  A common example of a wireless mesh network is the internet (Fleishman, 2017). Furthermore, wireless mesh networks rely on the same standards as traditional wireless networks, namely 802.11n and 802.11ac. Wireless mesh networks are effective in distributing connectivity between devices because the more nodes added to a network, the faster the network becomes, and the farther data can be transmitted. This is beneficial as both 802.11n and 802.11ac in traditional wireless environments have limited range and difficulties transmitting around physical obstructions. Wireless mesh networks operate at both the 2.4 GHz and 5 GHz frequency bands, thus devices that support the older 802.11n standard can connect to the network through the 2.4 GHz band, while both the 802.11n and 802.11ac standards can connect to the network through the faster, 5 GHz band. Although the 2.4 GHz band is prone to higher rates of interference due to increased traffic, it is better able to transmit data in the presence of physical obstacles such as buildings, walls, trees, etc. In wireless mesh networks, 802.11n is an adequate standard to use due to its dual-band capabilities; however, with each hop between devices, data rate and throughput are decreased. This presents problems for those that desire to use 802.11n for an entire mesh network system as this standard already operates at lower data rate and throughput values than those of 802.11ac.

Wireless mesh networks are not a new concept. Although they have been around for a while, these networks were not commonly used due to initial sizeable disadvantages (Roos, 2019). The largest disadvantage is that hops between devices in a wireless mesh environment lose upwards to half of the initial speed since wireless mesh networks employ a half-duplex communication architecture (Fleishman, 2017). This is especially impactful for devices operating with the 802.11n standard. With a maximum realistic speed of 240 Mbps, within one hop, this is reduced to nearly 120 Mbps and continually halved with every hop. Both data rate and throughput greatly suffer because of this. While this may be sufficient for light usage, this low bandwidth is not practical for daily operational network traffic. However, the 802.11ac standard alleviates this problem as it offers a realistic maximum speed of approximately 720 Mbps. As long as the number of hops is kept relatively small (say, three or four maximum), 802.11ac on wireless mesh still offers satisfactory bandwidth to be a viable alternative to traditional wireless networks. Furthermore, 802.11ac offers beamforming, a form of device targeting that would allow wireless mesh nodes to detect nearby, highly active devices and project stronger temporary signals in those directions (Fleishman, 2017). For these reasons, deployment of wireless mesh networks should be prepared using standard 802.11ac over 802.11n.

Both the 802.11n and 802.11ac IEEE standards were assessed in terms of a variety of factors as well as their deployment presence in wireless mesh networks. In general, standard 802.11ac is superior to 802.11n, though the latter comes at a lesser cost. With the continual advancement of technologies in the WLAN space, it is possible that these 802.11 standards will eventually be phased out as have been done with several legacy versions. Regardless, both 802.11n and 802.11ac offer many advantages over their predecessors and are currently employed in numerous assorted wireless environments.

References

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• FitzGerald, J., Dennis, A., & Durcikova, A. (2015). Business data communications and networking(12th ed.).
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• Kerravala, Z. (2018, October 09). Why 802.11ax (Wi-Fi 6) is the next big thing in Wi-Fi. Retrieved from https://www.networkworld.com/article/3215907/why-80211ax-is-the-next-big-thing-in-wi-fi.html
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• Vaughan-Nichols, S. J. (2010, March 15). Getting the most from 802.11n. Retrieved from https://www.itworld.com/article/2756011/getting-the-most-from-802-11n.html