802.11g vs 802.11n

The high speed wifi is more useful between local devices rather than interfacing with the internet. For instance, you might want to set up a media server, sending the video from your PC to TV.

example. These devices were G, but N are appearing on the market. I could see wireless network attached storage being draft N.

I think all the wifi routers that have gigabit on the lan are draft N. That was the driving force behind me going N over G. I do stream music, but that is find using G. I will eventually get around to streaming video, so the N will come in useful.

Even 802.11b at 10 Mbps would be adequate for a 7 Mbps internet connection.

802.11g is rated at 54 Mbps and would be useful for faster file exchanges within your own network. While it uses ODFM modulation, it is more robust (more reliable at longer ranges and less with than optimum signal levels), that advantage is lost as it requires more than twice the signal level for the higher speed. Locking down 802.11g to 10 Mbps would give you a very reliable wireless network. 802.11n could be considered an upgrade to 802.11g in terms of robustness and range.

If your 802.11b networks works fine the way it is, there's no advantage in spending the money to move up to 802.11n.

DTC hath wroth:

Required reading on MIMO:

This is very much up to date.

802.11n is all about speed. Great for video and massive local file transfers. Doesn't add much in the way of range. The rule-of-thumb is that 4 times the speed, will give you 1/2 the range. By the time you get to speeds greater than 54Mbits/sec, you're talking about 5 to 10 meter ranges.

However, that's for multiple streams (Airgo). To make sure that it's a total muddle, 802.11n Draft 2 includes beam forming and steering (Atheros and Ruckus Wireless), which for some amazing reason is classified as MIMO. It offers no speed enhancements, but does offer substantial indoor reflection and interference reduction. One thing that all the various MIMO mutations have in common is that you cannot easily add an aftermarket antenna (or antennas). If you can't get the range with what is supplied by the manufacturer, too bad.

Ummm... nope. Thruput is roughly half the connection speed. An

11mbit/sec connection would yield about 5Mbits/sec thruput, which is much less than the 7Mbit/sec internet speed. The message header for the OP shows that he's on Cox.net, which has "PowerBoost" speeds to about 10Mbits/sec for preferred and premier service levels. To utilize 10Mbits/sec thruput, he needs at least a 24Mbit/sec connection speed.

Locking it down at 24Mbits/sec would be required to prevent bandwidth constipation at 10Mbits/sec thruput. However, that doesn't work too well. I've been recommending that locking down the speed to the slower OFDM speeds offers a reliability improvement in that the access point isn't constantly trying to go as fast as possible. That works well at the slower speeds (I use 12Mbits/sec OFDM). That will a bit slow for a 7Mbit/sec cable internet, but will not work if the OP has burstable service. However, my experiments with locking the speed at much faster rates (I was testing at 36Mbits/sec) has not been so wonderful. Packet loss starts to creep up. Susceptibility to noise interference increases. Signal loss and disconnects are more abrupt and of course, at a shorter range. It will probably work just fine for a closed room environment (coffee shop, conference room, bedroom, etc), but isn't too good when going through walls, floors, or in the presence of substantial interference.

I haven't tried the same tests with any of the MIMO devices, so I can tell if MIMO adds anything. I doubt it because outside of fairly short ranges, the typical Airgo MIMO access point reverts to

802.11b/g.

Incidentally, many low end routers can barely move data at cable internet speeds, or handle many connections:

Ummm... I hope you're not referring to the 2x, 4x, now up to 12x stickers that are appearing on the retail packages? When I see the manufactories run a BER/PER test, at various ranges and speeds, I might believe that manure. Meanwhile, some MIMO articles:

are quite revealing.

Sure there is. There's great benefits to all the 802.11n Draft 2 confusion. It's bad enough that most of what I buy is obsolete in a few years. With 802.11n Draft 2, I can buy products that are obsolete on arrival and with no guarantee of a later upgrade to the final standard. There's also no incentive to produce such an upgrade path, because that will cut into future replacement sales.

Bah Humbug; E. Scrooge and Associates.

~ jrb wrote: ~ > I am trying to figure out if going to 802.11n from an 802.11g is ~ > really worth it. My internet service is listed as being upto 7MB. Any ~ > thoughts on the switch?

~ Even 802.11b at 10 Mbps would be adequate for a 7 Mbps internet connection.

No it would not. The maximum nominal signaling rate of 802.11b is 11Mbps. However, the 802.11 MAC layer has a lot of overhead, so even with a perfect

11Mbps 802.11b physical/MAC layer, this will translate (at the IP layer) to a best case throughput rate of 5.5 - 6Mbps.

So, 802.11b would be a bottleneck for a 7Mbps Internet connection.

(Terminology note: when I say Mbps, by that I mean MegaBITS per second, where "Mega" denotes one million [1,000,000].)

~ 802.11g is rated at 54 Mbps and would be useful for faster file ~ exchanges within your own network. While it uses ODFM modulation, it is ~ more robust (more reliable at longer ranges and less with than optimum ~ signal levels), that advantage is lost as it requires more than twice ~ the signal level for the higher speed.

802.11g OFDM is more robust, and with a perfect 54Mbps nominal signaling rate will yield an IP layer throughput of up to 27Mbps or so.

~ Locking down 802.11g to 10 Mbps ~ would give you a very reliable wireless network.

10Mbps is not an 802.11g rate. You could cap 802.11g at the 24Mbps signaling rate which would give you a maximum throughput of about 12Mbps, which should be sufficient to prevent the wireless link from being a bottleneck for your Internet traffic.

However, if there are 802.11b-only clients present in your cell, then the 802.11g protection mechanisms may reduce your maximum throughput, such that your nominal 24Mbps signaling rate may no longer be sufficient to yield 7Mbps of throughput.

Therefore, I would probably stick with the maximum 802.11g rate of

54Mbps, unless you have reason to be that the clients and/or APs are doing a suboptimal job of rate selection and would therefore benefit from a rate cap.

~ 802.11n could be considered an upgrade to 802.11g in terms of robustness ~ and range. ~ ~ If your 802.11b networks works fine the way it is, there's no advantage ~ in spending the money to move up to 802.11n.

Roger that.

References:

Capacity Coverage & Deployment Considerations for IEEE 802.11g Cisco whitepaper

When Is 54 Not Equal to 54? A Look at 802.11a, b, and g Throughput Article by Michael Gast Aaron

Let me jump in here a minute. My interest in 'n' is, by far, more for the increased range. Are you, and others, saying the range is not that much greater? I need to reach wirelessly about 80-100 feet through 3 walls and one floor. My 'g' can't reach that far.

I've heard of that with consumer gear. We lock the speed down for our tier two (three to six mile distance) radios to minimize complaints of widely varying speeds. At six miles, we can certainly throw a faster signal, but with only a 10 dB fade margin.

Good grief no! Besides, I don't use the consumer crap.

Those photos prompted me to open my dead Netgear WNR854T. It uses a Marvel board. The interesting thing is they used ferrite chokes on the antenna coax.

I just happen to dribble by Office Max. On some 802.11n products being sold, the box declared: 4x the range. 12x the speed Sounds great? Well, they lie. (Everybody lies, but that's ok because nobody can understand the numbers anyway).

First, you're NOT going to get both 4x the range and 12x the speed at the same time. If you believe the hype, it's one or the other.

2nd, 4 time the range of what? Compared to what device and under what conditions? I'm a bit busy right now (leaky office roof) so I'm going to suggest that you do the necessary Googling and see if any of the vendors that use this 4x and 12x manure bother to specify test conditions on their web piles. They probably do, but see if it actually resembles something you can use for comparison. Look for at what range they did the test, with what error rate, and using what client device for testing.

Neither can an 802.11n Draft 2 router go through 3 assorted walls of unspecified material and one floor of more of the same. If it's concrete, stucco, chicken wire, or aluminum foil backed insulation, you're lucky if it can go through one wall. The only way I know of going through 3 walls and a floor is with an electric drill and CAT5 cable. If desperate, think about power line (HomePlug) or phone line (HomePNA) networking.

Incidentally, my rule of thumb is where the 4x and 12x crap came from. The way Airgo style MIMO (spatial mux) works is to transmit multiple streams of data at the same time. So, if you're getting perhaps 100ft of reliable range at 25 Mbits/sec, then with Airgo style MIMO, you'll get two streams or twice the thruput. However, you can always trade speed for range. A 2nd stream will give you SQRT(2) times the range, if you drop the TOTAL speed of the two streams back down to the previous 25Mbits/sec. If you have 4 streams, and slow things down to

25Mbits/sec, you'll go 2x as far. To go 4x the range, you need 16 streams, which I don't think any of the current incantations are able to deliver. Similarly, if you're expecting 12x times the speed, you'll need 12 streams, which is also stretching things a bit. Of course the spatial mux is far from perfect and tends to create some self interference. Your mileage may vary.

Increased range? sure...in an open environment.

Bubble pack FRS radios can go 12 miles...from a mountain top down into a valley.

Well, my walls/floors are typical residential wood/drywall. HomePlug has worked tolerably well but, since I tend to move around a room, I'd rather not be tethered to a wire. Is there a way to send a signal to a remote network device (wireless or wired) and have the remote device send a wireless signal so I'm not forced to connect my laptop to a wire/cable?

jay lunis hath wroth:

Got time to make a quick measurement? Fire up Netstumbler or anything that gives a signal strength graph in dBm. Lock the speed on your wireless access point to some fixed OFDM value.

Walk around your house starting with going through 1 wall. Get an average signal strength value and record the straight line distance between the access point and the laptop. Try it again for 2 and 3 walls. If possible, also try it in an open area, with no walls.

What you should see is that doubling the distance, should cause a -6dB drop in signal level. Any loss in exess of this value, is attenuation in the walls. That will give you a real number to work with for calculating wall attentuation. I can help with the calcs if you email to me the setup and numbers.

As for HomePlug and HomePNA, both have wireless bridges and repeaters that use the phone or power lines as a backhaul. For example:

Both use the power line for a backhaul. One acts as a wireless repeater at both ends. The other uses wireless only at one end. The other end gets a CAT5 cable plugged into your router.

Incidentally, with such an arrangement, you really don't need wireless. Your laptop is going to be plugged into the battery charger, which is plugged into the wall. You might as well run a CAT5 cable to a HomePlug ethernet bridge using the same wall plug. No need for wireless.

Not quite. I admit to being lazy. Don't want to unplug a bridge and take it to another outlet. Don't do that now with my battery charger. I sit/go wherever I want and use the laptop until I get a low battery alarm (which, in my case, is seldom). Often don't have a power cord attached to the laptop. But there is hope. I'll go to the link you provide and get the bridge/repeater. From your description, that should do what I want without moving to 'n' equipment. And it will save me from taking signal strength measurements.

jay lunis hath wroth:

I always wondered why people buy wireless devices. Now, I know.

Some more products:

Make sure you get at least the 85Mbits/sec HomePlug flavor. The

14Mbit/sec flavor is just too slow. I haven't tried 200Mbit/sec (HomePlug AV) yet.

Think plan B... I have a linksys wrt300n downstairs plugged into the cable modem, and the router output to both a homeplug (14.4) and a netgear (85) on a power strip, so at any outlet in the house (or outside, when nice, by my hammock) .. I have the other parts of the homeplug and netgear plugged into wrt54g's that I got at walmart for under $50.. gives me both wired and wireless wherever I plug it in... Just a few caveats, plug the powerline stuff into the router part, have em both on the same 3rd ip addy/segment so it will let you see the rest of the network, and use a different ssid/channel so you don't wirelessly connect to the wrong one. Benefit is, that way I have both wired and wireless at any plug in the house, and any place that is a dead spot, I just plug the thing in and can get full internet and/or access to my local network... You gotta plug the powerline stuff in, so why not a power strip ($2) that not only does that, but the wap/router, and has extra plugs? Real handy when you want to move it all, just plug it in wherever you want Sounds like you already have the major pieces you need......

Just to be clear, you could do it all wirelessly, but It was actually cheaper to get the wap/routers at walmart and have both wired and wireless by any plug....

I'm a little confused here. Plug the modem and router into an outlet away from the PC? I suppose this means the PC is plugged into a homeplug. And you have 2 networks ssid's? One for wired and one for wireless?

Nope, i have one wap/router downstairs connected direct to the cable modem, and that router output is connected directly to a netgear/85 (and several TB's of network storage).. At other places in the house, I have both a second wap/router and the second part of the ethernet bridge connected to the *router* parts of additional wap/routers (NOT the wan port), that I can plug in anywhere in the house, and essentially have another wifi ap (or plug cables into them if needed, like for my Tivo that wants wired - have 5 - 4 can do wireless/USB, but 1 only wired-ethernet).. purpose for a different ssid/channel is so that instead of seamlessly roamng (and possiblly connecting or staying connected to the weaker one, I just use a unique ssid/channel rather than trying to putz with seamless roaming... As for multiple wap/routers, yes I happen to have several (tivo only use wep, so i want internet but not access to my other puters), so in the starting ip i have x.x.1.x and x.x.2.x (one private one public) So I do the ssid's to differentiate ppinmd-private and ppinmd-public)... had the powerline stuff already, and just picked up the linksys wap/routers for under $50 each at walmart (at under $50 a pop was easier to get the same thing, in case one dies I have spares) Is that clear as mud? :)