Question about antennas and streams when upgrading a laptop card from N to AC

[autobulb]

Alright so I did as much research as I possibly can and I learned a great deal about these newer technologies from this website but I still can't find a clear explanation of "streams" and how they relate to the number of antenna connectors in a laptop.

Here is my understanding so far, just to see if I am thinking about this correctly:

For wireless-N, each stream has a theoretical max throughput of 150mbps. So, dual stream is 350mbps and triple stream is 450mbps. This is easy to understand when it comes to routers as the specifications are posted regarding the router. The problem I have is when it comes to laptop wireless cards. So, my card, the Intel Wireless-N 135 is a single stream card capable of 150mbps. It has two antenna connectors. When I look at Intel's dual stream capable cards, they also have two antenna connectors. So, my first question is if I get a dual stream card, will I actually be able to use dual stream and get the (theoretical) 300mbps speed using those same two connectors? Triple stream cards have three connectors, but I don't have that third connector so I am going to consider myself limited to one or two streams for now.

The next question is if I wanted to upgrade to an AC network. Again, talking about streams, each one for AC is 433mbps. So we have theoretical max speeds of 433, 866, and 1300 for single, dual, and triple respectively. My question is if these same connector types for wireless-N are compatible with this new AC standard? Can I basically just change my N card to an AC card, plug in the antennas and be good to go? How many streams will I be capable of, with 2 antenna connectors?

Thanks in advance for explanations and help.

 

[thiggins]

I understand your confusion. The problem is that some cards have radios with more receive chains than transmit. They do this to increase receive gain. But the number of transmit chains determines the maximum link rate.

So, even though your single-stream N150 card has two antennas, it will be limited to a maximum link rate of 150 Mbps. Remember this is with a 40 MHz wide channel.

Yes, you can substitute an AC card for your N card and use the same antennas.

What you don't want to do is put a card with three antenna connectors into a notebook that has only two antennas (or a two-connector card into a one-antenna notebook).

This will cause bad performance because the card will report that it supports higher link rates to the AP it associates with. But since it doesn't have the antennas to support the link rate, performance will suffer as the client and AP keep switching link rates to try to find one that works.

 

[autobulb]

Thanks so much for your response. I have been racking my brains with this for days now.

So, for my laptop with 2 antennas, the best possible solution for maximum bandwidth would be to get a dual stream AC card, which would give me a link rate of 867, and compatible router, yes?

I am pretty comfortable with dismantling laptops, would it be worth the time investment in purchasing and routing/installing that third antenna? Right now, according to my Speedtest result, I have a maximum bandwidth of 100mbps downlink and a little less uplink when connected directly to my modem with a 1gbps link rate. So, really if I could achieve those actual speeds, I would be pretty happy. Is that more realistic with 867 or 1300 link rate?

 

[thiggins]

You get top speeds only in 5 GHz and they drop pretty quickly with distance. Here's a comparison of the top-ranked AC1750 and AC1200 routers.

 

[stevech]

Thanks so much for your response. I have been racking my brains with this for days now.

So, for my laptop with 2 antennas, the best possible solution for maximum bandwidth would be to get a dual stream AC card, which would give me a link rate of 867, and compatible router, yes?

I am pretty comfortable with dismantling laptops, would it be worth the time investment in purchasing and routing/installing that third antenna? Right now, according to my Speedtest result, I have a maximum bandwidth of 100mbps downlink and a little less uplink when connected directly to my modem with a 1gbps link rate. So, really if I could achieve those actual speeds, I would be pretty happy. Is that more realistic with 867 or 1300 link rate?

Is you goal to get these high speeds because you'd do lots of huge file size transfers within your LAN and via WiFi? Of course, your ISP speed to the Internet is probably far less than even 11n speeds. Transferring batches of ordinary-sized files won't tax 11n speeds. And within the LAN, streaming Netflix and such is well below 11g speeds.

 

[autobulb]

Is you goal to get these high speeds because you'd do lots of huge file size transfers within your LAN and via WiFi? Of course, your ISP speed to the Internet is probably far less than even 11n speeds. Transferring batches of ordinary-sized files won't tax 11n speeds. And within the LAN, streaming Netflix and such is well below 11g speeds.

Well, like I wrote in the last post, I get about 100mbps download from Speedtest, so I don't want my Wifi to bottleneck that. Even though N goes up to 450mbps, I will only be able to do 300mbps since I only have two antennas. But because of overhead/less than perfect signal the actual throughput will be much lower, so I want to make sure I can cover an actual 100mbps of bandwidth. And then, since I will need to upgrade my router and wireless card (both are only single stream N, 2.4ghz) I figure it's worth it just spending a little more money to go to AC for more bandwidth, especially since I do a lot of transferring of large media files through the LAN. Your thoughts?

 

[RMerlin]

Considering how inexpensive even an Intel Centrino 6235 is these days, upgrading your 150 Mbps card to at least a 300 Mbps card is well worth the time and money. If you want to spend a bit more and go all the way to an Intel 7260 (make SURE it's a 802.11ac-capable SKU - Intel's model numbering is VERY confusing!), it's definitely worth considering it since the price difference isn't very big. Myself, I replaced the crappy 2.4 GHz 150 Mbps card with a dual band 300 Mbps card last year, and it was well worth the 25$. It also gave me Bluetooth along the way.

One important caveeat however: some laptop manufacturers use whitelists hardcoded in the BIOS that will only allow specific cards. HP and Lenovo are two manufacturers which does it - others might also do it. I strongly recommend researching on the web first to see if anyone has upgraded your laptop model first. My Asus K53E had no trouble taking the Intel Centrino 6230 I installed.

Now, I'm considering getting a 7260 card, but I'm not in any hurry as Intel's driver seems to be really buggy at this point.

 

[autobulb]

I have a whitebrand version of the MSI GE60, which is available as built to order from many different vendors offering many different wireless cards, so I'm guessing it's not locked down.

Right now, figuring out which router to get is the hardest decision for me because where I am, the only company that offers a decent range of models is Buffalo, which I don't exactly trust. The model I wanted has DDWRT listed as "work in progress." I will feel better if there is a build for it at some point.

 

[stevech]

I get about 100mbps download from Speedtest, so I don't want my Wifi to bottleneck that.

Wow. From ISPs here, I'd have to take a second mortgage on my home to get that speed. Do you mind saying how much this costs? My ISP has a near monopoly and says $45/mo for 15/1mbps is all we deserve!

As to the speed you mention for WiFi... don't forget that the WiFi indicated bit rates are the raw burst rate for frames in a half-duplex medium. The actual IP throughput, sans interference and weak signals, is about 60% of the WiFi indicated burst rate.

 

[autobulb]

Wow. From ISPs here, I'd have to take a second mortgage on my home to get that speed. Do you mind saying how much this costs? My ISP has a near monopoly and says $45/mo for 15/1mbps is all we deserve!

As to the speed you mention for WiFi... don't forget that the WiFi indicated bit rates are the raw burst rate for frames in a half-duplex medium. The actual IP throughput, sans interference and weak signals, is about 60% of the WiFi indicated burst rate.

I don't live in the U.S. In quite a few cities of Japan, fiber is pretty prevalent. A lot of the cabling is above ground so it's easy to pull a cable off the street and install it into basically any home. In my area, the average price for those speeds are about 40 dollars a month. They also give you a bonus for signing up, I got about $200 in gift certificates usable in all types of major stores.

Regarding wifi, yeah, the reason I am looking to AC is because I want to get as much bandwidth as possible since there is a lot of drop off.

 

[stevech]

Ah.
In the US, all we have for fiber to the home is Verizon FIOS and that is very territorial due to idiocy in the post-deregulation era.

AT&T promotes their U-Verse as fiber based, to the naive, but in truth, it's 40 year old copper wires to the home trying to pass 30MHz on which they try to get a 3 or so video streams + IP. Fiber is to their VRAD box at a curb typically 500-1000 ft. away.

That's about all we have in the near future - perhaps due to our high population density in suburban rather than urban where it's cheaper per subscriber to do fiber to the home.