“Increased Speed for Wireless Users Soon” read the headline of a recent news article. As I suspected, the article touted the IEEE 802.11ac amendment and its improvements over today’s wireless offerings. This caused me to step back and get some perspective.
As a wireless user, just hearing “increased speed” gets my attention. After all, that’s probably the one thing that end users really care about, and it sounds so simple and powerful. As a wireless engineer, I’m also acquainted with the incredible hardware, architecture, and configuration that all work behind the scenes to make the wireless magic happen. The more I learn about wireless technologies, the more my mouth hangs open in awe.
Wired networks can carry high bandwidth data streams over physical cables. Data transmissions are well-defined and well-contained inside those cables. As long as the cables are built according to a standard, there aren’t many variables that can affect the data delivery. In a way, such a predictable medium almost takes the fun out of engineering a network.
Wireless networks, on the other hand, use the air or free space as the delivery medium. There aren’t many constraints about free space that help a wireless signal move along. Instead, the wireless world is full of variables that must be overcome. Even free space itself is working against an RF signal – a signal transmitted out in the open will dampen out exponentially the further it travels. That is because the signal and its RF energy spread out in three dimensions along the way. Things tend to get worse when objects are placed in free space. RF signals can be attenuated as they pass through objects, reflected as they bounce off objects, diffracted as they bend around objects, and so on. The signal that is received is seldom identical to the signal that was transmitted.
Beyond that, transmitters can overlap and interfere with each other. Other devices can interfere with the wireless signals we try to receive. Two devices might not be able to hear each other if their transmit power levels are not identical. And I haven’t even mentioned the hurdles of sending increasing amounts of data over an RF signal reliably. Wireless networking is so full of variables that I’m often amazed that it even works! Maybe it is this amazement that makes me like it.
By its nature, wireless LAN technology is complex - very complex. The IEEE 802.11 standard is now over 2,500 pages long, and new amendments are being developed all the time. There are many different amendments tackling so many new and different problems. Wireless networking is ever-changing and evolving, giving us cool new things to learn and use as time goes by.
Wireless networks are also growing and scaling like never before. Cisco wireless LAN controllers can support over 1,000 APs each and can be configured for high availability. Wireless bandwidth has improved so much that it stays on par with that of wired connections. What began as 1 Mbps quickly grew to 11 Mbps on a single channel with 802.11b. Shortly after, devices using 802.11g and 802.11a could share up to 54 Mbps on a channel. The advent of 802.11n in 2009 brought about a rich toolkit of high throughput features that worked together to offer up to 600 Mbps.
Right now we sit on the edge of 802.11ac, which will allow devices to leverage superior modulation, multiple radios, and bonded channels to share a maximum of 6.9 Gbps! The 802.11ac amendment will hit the ground in two waves over time. Granted, most of these throughput figures are theoretical maximums, but wow!
Wireless networks involve a diverse set of technologies and skills. That makes being a wireless engineer more challenging and more future proof than other disciplines. You might start out by learning basic RF principles, but soon you could be involved with things like the following:
- 802.11 configuration
- Security mechanisms
- Wireless intrusion prevention systems
- Rogue device detection
- Assessing interference and “air” quality
- High availability
- IP multicast
- Workgroup bridges
- Point-to-point wireless bridges
- Indoor and outdoor wireless mesh networks
- Quality of service
- Voice over wireless LANs
The list of possibilities goes on and on. You can also learn how to conduct site surveys before and after APs are deployed, how to validate wireless client behavior, how to manage wireless networks, how to troubleshoot complex problems, and how to track down RF interference. And the day is coming when you could implement voice call handoff between 3G/4G cell and wireless LAN networks. All of these job functions require a creative mind and offer a growing career path.
Beyond the raw wireless technology, I’m equally intrigued with the wide variety of wireless client devices that have to coexist on a wireless LAN. Here are some examples of clients I have come across in just one medical enterprise:
- Mobile PCs with a secure portal to patient data
- Handheld devices that record data at the patient’s bedside
- Hospital beds that report information about the patients lying in them
- RFID tags used to track location of patients and objects in real time
- Tiny voice communicators that medical staff use as they move around the buildings
- Robots that carry lab specimens from building to building
- Mobile X-ray and ultrasound machines
- Wireless phones
- Guest devices
With so many devices roaming around, the AP layout and antenna selection can be unique challenges too. For example, an emergency department the size of a football field is crowded with medical staff making critical voice calls over the wireless LAN. Thirty elevators need seamless wireless coverage for voice calls. Several helipads on the roof need outdoor coverage for staff moving to and from helicopters. Large auditoriums and long study halls require special coverage patterns.
If you work with wireless networks, surely you have come across equally interesting and challenging scenarios. How are you preparing yourself to deal with all of the wireless technologies and applications you are faced with both today and tomorrow? If you are just beginning, where should you start? Cisco has recognized the need for wireless training - especially to implement and support Cisco Unified Wireless Networks. Each of the traditional CCNA, CCNP, and CCIE certification tracks now has a wireless specialization. You can find out more information at http://www.cisco.com/web/learning/certifications/index.html. You should also consider the Certified Wireless Network Professional (CWNP), a set of vendor-neutral wireless certifications which tend to focus on the 802.11 standard and an in-depth technical foundation. CWNP offers a full range of certs and training from basic fundamentals to a wireless network expert level.