Wireless Networks

This post will cover various aspects of the Networking section of the CompTIA A+ Core 1 certification endeavor.

Table of contents

• Overview
• 802.11a
• 802.11b
• 802.11g
• 802.11n
• 802.11ac
• 802.11ax
• 802.11x - in summary
• Fixed wireless
• Radio frequency identification
• Near field communication
• Bluetooth

Overview

The standards for networking standards come from the IEEE 802 committee. These specifications apply to local area networks (LANs) and metropolitan area networks (MANs). Without these standards, it would be much more difficult to connect to systems not using the same set of networking equipment. Standardizing protocols helps ensure multiple types of devices can connect to multiple network types. It also helps make sure network management isn’t the challenge it could be if standards weren’t in place.

Better-known specifications include 802.3 Ethernet, 802.11 Wi-Fi and 802.15 Bluetooth/Zigbee. However, some of these standards have been labeled as disbanded or hibernating, and are either superseded by newer standards or being reworked. Using an open process, the LAN/MAN Standards Committee (LMSC) advocates for these standards globally.

This table displays the working groups of the 802 specifications:

IEEE 802 is divided into different parts that cover the physical and data link aspects of networking. The LMSC has made more than 70 standards for IEEE 802. Some commonly used standards include those for Ethernet, bridging and virtual bridged LANs, wireless LANs, wireless MANs, wireless personal area networks (PANs) and radio access networks, as well as media independent handover services.

802.11a

802.11a was one of the first Wi-Fi communication standards created in the IEEE 802.11 standards family. The original 802.11 did not gain widespread deployment due to its excessively slow speed.

802.11a operated in a frequency spectrum of around 5 GHz, supporting a maximum theoretical bandwidth of 54 Mbps. Although this doesn’t seem very fast now, back in 1999 when this was first released, that was a great deal of speed on a network that suddenly was able to operate wirelessly.

802.11b

About the same time that 802.11a was released, the IEEE also finalized the 802.11b standard. This is not an upgrade to the a. Instead this is a completely different standard that operates with different frequencies and different speeds. 802.11b supports a theoretical speed of up to 11 Mbps operating at a frequency spectrum of 2.4 GHz; much slower than the 54Mbps we were able to get with 802.11a.

While 802.11a operated at higher frequencies, the objects around would tend to absorb the signals, whereas with 802.11b they tend to bounce off of those devices. The higher frequency also means 802.11a signals had more difficulty penetrating walls and other obstructions. Thus making the range for 802.11b greater.

802.11g

In 2002 and 2003, WLAN products supporting a newer standard called 802.11g emerged. 802.11g attempts to combine the best of both 802.11a and 802.11b. 802.11g supports bandwidth up to 54 Mbps and uses the 2.4 GHz frequency for greater range. 802.11g is backward compatible with 802.11b, meaning that 802.11g access points will work with 802.11b wireless network adapters and vice versa.

• Pros of 802.11g: Supported by essentially all wireless devices and network equipment in use today; least expensive option
• Cons of 802.11g: Entire network slows to match any 802.11b devices on the network; slowest/oldest standard still in use

802.11n

802.11n (also sometimes known as Wireless 4) was designed to improve on 802.11g in the bandwidth it supports by using several wireless signals and antennas called MIMO technology or Multiple Input Multiple Output. Industry standards groups ratified 802.11n in 2009 with specifications providing up to 600 Mbps of network bandwidth. 802.11n also offers a somewhat better range over earlier Wi-Fi standards due to its increased signal intensity, and it is backward-compatible with 802.11a/b/g gear.

• Pros of 802.11n: Significant bandwidth improvement, up to 40MHz, from previous standards; wide support across devices and network gear (5GHz and 2.4GHz simultaneously)
• Cons of 802.11n: More expensive to implement than 802.11g; use of multiple signals may interfere with nearby 802.11b/g based networks

802.11ac

The generation of Wi-Fi that first signaled popular use, 802.11ac, uses dual-band wireless technology, supporting simultaneous connections on both 2.4 GHz and 5 GHz Wi-Fi devices. 802.11ac offers backward compatibility to 802.11a/b/g/n and bandwidth rated up to 1300 Mbps on the 5 GHz band plus up to 450 Mbps on 2.4 GHz. Most home wireless routers are compliant with this standard.

802.11ac is the most expensive to implement; performance improvements only noticeable in high-bandwidth applications. We can also use much more of that wireless spectrum simultaneously because 802.11ac will support up to 160 MHz of a channel bandwidth. It not only uses multiple input multiple output, but increases the capabilities of that MIMO by adding multi-user MIMO to allow multiple users to communicate over multiple input and multiple output simultaneously. This standard supports up to eight of those multi-user MIMO streams, which translates into a maximum total throughput of nearly 7GBs per second for 802.11ac.

802.11ax

Branded as Wi-Fi 6, the 802.11ax standard went live in 2019 and will replace 802.11ac as the de facto wireless standard. Wi-Fi 6 maxes out at 10 GBps, uses less power, is more reliable in congested environments, and supports better security. The standard also supports many different channel widths. So we can have bandwidth of 20, 40, 80, and 160 MHz for people communicating on that wireless network.

If we look at the standards for 802.11ax, we can get a total throughput per channel of about 1.2 GBps. This is a relatively small increase in throughput when you compare it to other improvements in the standards through the years. But there is a difference in how this particular version was designed. 802.11ax was designed to solve some of the problems we have with using these wireless networks in areas where there are large number of people.

So if you’re at a sporting event or a trade show, you may find it difficult sometimes to communicate over these wireless networks. With 802.11ax, we introduced a new form of communicating called orthogonal frequency division multiple access or OFDMA. This takes a type of communication that we’ve used for some time on our cellular networks and brings it into the world of 802.11. This allows us to put 802.11ax networks in places with large numbers of people and be able to communicate without a huge loss in efficiency over those wireless networks.

802.11x - in summary

802.11 has a long history from it’s first release in the late 90’s to as recently as 2019.

This table displays a quick summary of the 802.11 specifications:

Fixed wireless

Fixed wireless networking refers to the operation of wireless devices in fixed locations such as homes and offices. Fixed wireless devices usually derive their electrical power from utility mains, unlike mobile wireless devices, which tend to be battery powered.

Fixed wireless is the typical form of internet deployed in areas with no fiber internet infrastructure, mainly rural areas. It is broadcast from towers through airwaves to receivers that the service provider will have installed on the user’s property. For fixed wireless internet connections to work, the receiver needs to be within around 10 miles from the fixed wireless internet service provider’s tower.

Some of the most important benefits of fixed wireless are as follows:

• Subscribers can be added or moved to a certain extent without modifying the network infrastructure.
• Subscribers in remote areas can be brought into a network without the need for stringing new cables or optical fiber across the countryside.
• Broad bandwidth is possible because there are no wires or cables to introduce reactance into the connection. Reactance limits bandwidth by preventing signals higher than a certain frequency from efficiently propagating.
• As the number of subscribers increases, the connection cost per subscriber goes down making this a more cost-effective option.

Fixed wireless is one method to deliver internet connections to wireless routers, APs or modems used for Wi-Fi, but it is not a replacement for a Wi-Fi network altogether. Organizations, businesses or homes that run fixed wireless internet can’t automatically connect to the receiver antenna to give their devices internet access. Instead, that fixed wireless receiver has to connect to an internet modem or router, which powers the Wi-Fi network on which devices connect.

Radio frequency identification

Radio frequency identification (RFID) uses close to the same technology as NFC, but allows further communication.

There are three main components:

• Tag: container that digitizes and stores information. You have a reader that reads that information out of the tag.
  • Active RFID. An active RFID tag has its own power source, often a battery. They cover distances of 100 meters or 300 feet.
  • Passive RFID. A passive RFID tag receives its power from the reading antenna, whose electromagnetic wave induces a current in the RFID tag’s antenna. They cover distances close to near field communication or 10-20 feet max.
• Reader: reads information out of a tag.
• Antenna: associated with the wireless communication.

Near field communication

Near field communication (NFC) is a point-to-point contact technology that allows two devices, like a smartphone and a payments terminal, to talk to each other when they’re very close together (0- 2 cm). It runs over 13.56 MHz and can be used to transfer information.

We’ve extended the use of RFID into our mobile phones and our smartwatches through the use of NFC. It’s a way for our mobile devices to be able to have two way conversations with other devices that we might use. For example, we might be checking out at a store and we can use our phone or our smartwatch to pay for those goods because we’ve associated our credit card with the NFC technology that’s in our devices. You might also see NFC used if you need to pair two Bluetooth devices.

Bluetooth

Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks. In the most widely used mode, transmission power is limited to 2.4 GHz, giving it a very short range of up to 10 meters or 30 feet. We often refer to this as a personal area network (PAN).

In the early days, Bluetooth was really focused on internet of thing devices, and while trying to discover other devices the battery would drain pretty bad. Bluetooth 4.0 introduced Bluetooth LE (low energy), which consumed less power.