The folks that brought us the specifications we have grown to know and love concerning different types of cabling – you know the Cat5e and Cat6 types of twisted pair cabling. Those folks have now stepped up and entered the fray of Wireless LAN Design.
Some of what they are suggesting is fine. Things like ensuring Gigabit Ethernet is available to all access points. But some of the other ‘wacky’ bits of the spec leave a lot to be desired. In fact, they are so far out there, you could consider them to be humorous.
First of all – here is a link to a draft of the TIA’s TSB-162-A standard for your own review.
Like all standards, it is full of acronyms, and specific terminology. As well as very detailed descriptions and definitions. That is just the way of standards. They need to be highly specific.
First of all, I’ve just got to say it made it very hard for me to read up on any of the documents concerning this new standard… they keep referring to Access Points as WAP’s… arrrgh! (nuff said)
The TIA thinks it makes the process of cabling for WLAN’s easier by recommending a ‘grid’ pattern. TIA TSB-162-A suggests a square grid of coverage areas, each 18 meters wide. Each cable run to be of Category 6A cable. Each location to have a 13m drop-cable to allow movement from the center of each grid.
They are suggesting by using this grid pattern, Wi-Fi design is not needed, just place an AP at every grid point and you’ll be done. As a ‘side-note’ they suggest an RF survey to be completed to optimize AP placement within a given cell.
The choice of Category 6A cabling for future installs is a wise alternative, given the backhaul capabilities of an 802.11ac Wave 2 Access Point. Not to mention an updated IEEE 802.3at Power over Ethernet requirements.
They also suggest at least two runs of Category 6A cabling to each of these zones.
I can see the idea of ‘future proofing’ the cabling infrastructure. The grid pattern, with long service loops will allow for a wide variety of access point placement options.
But the idea of placing Access Points every 18 meters is just ludicrous.
Here is an example of just such a grid layout for cabling.
Note the use of multiple APs inside certain grids – their recommendation is this higher density of AP’s is for rooms like conference rooms or classrooms.
Here is the same floor plan using AirMagnet Planner to show coverage at -65dBm with only three access points. The entire floor is covered – and the majority has both primary and secondary coverage. (overlap).
Now, lets see what this same RF planner tool looks like when we put an AP in every planned grid.
Just this of the co-channel contention areas in 2.4GHz. Here is the coverage pattern for a single AP at -65dBm.
So following the TIA TSB-162-A standard would be a great way to plan for cabling in a new building. You would for sure have more than adequate cable drops for wherever you’d want to place your access points.
I would just strongly recommend we follow industry standards still in designing Wireless LANs.
- Define all your RF requirements
- Design to meet all the requirements
- Install the gear – using TSB-162-A might be helpful here
- Validate that all RF requirements are met
- Remediate any that are below required specifications
Remember – it isn’t merely delivery of RF Coverage – RSSI alone is not enough. We need to be sure we meet ALL requirements.
- Primary RSSI
- Secondary RSSI (overlap)
- Signal to Noise Ratio
- Co-Channel Contention – frequency reuse
- Channel Utilization
- Data Rates
- Jitter/Latency/Packet Loss
- Roaming Handoff Times
- Quality of Service
- Retry Error Rates
- CRC Error Rates