wifi multiplexing

[ilyas001]

hello guys , well i know that to have multiplexing in wifi we will need to have different channels at the same time , so my question here , do we need a different antenna for each channel  ?

[Mira Yurizaki]

Yes.

[ilyas001]

4 minutes ago, M.Yurizaki said:

Yes.

thanks . well now im gonna ask another question but it's gonna be a mess to try to understand me so you can correct me ( i say what i have in mind so that you can understand and then correct me ) pls

what does 802.11 means in the first place , because let's take for exemple i'm using 802.11 a and i have 54 mo/bits max speed it says that without multi channels i can't use the full band because it's only half duplex so 54 is just Theodoric because i will have a debit of 27 mb/s only right ? so if i m right i will use another antenna using another channel so i sue one for transmission and another for acknowledgment right ? so now i can use fully 54 mb/s so if i have for example 4 antenna's , will i have a bandwidth of 108 mb/bits then ?  so each channel is on itself another 802.11a connection just configured differently right ? i

[Mira Yurizaki]

10 minutes ago, ilyas001 said:

thanks . well now im gonna ask another question but it's gonna be a mess to try to understand me so you can correct me ( i say what i have in mind so that you can understand and then correct me ) pls

what does 802.11 means in the first place , because let's take for exemple i'm using 802.11 a and i have 54 mo/bits max speed it says that without multi channels i can't use the full band because it's only half duplex so 54 is just Theodoric because i will have a debit of 27 mb/s only right ? so if i m right i will use another antenna using another channel so i sue one for transmission and another for acknowledgment right ? so now i can use fully 54 mb/s so if i have for example 4 antenna's , will i have a bandwidth of 108 mb/bits then ?  so each channel is on itself another 802.11a connection just configured differently right ? i

Wi-Fi uses what is called the IEEE 802.11 standards, which tell someone how to create a standardized Wi-Fi network so it's compatible with any other Wi-Fi network. The letters after that refers to a "version" or "revision" of that standard.

 

Radio signals are always half-duplex, meaning they cannot transmit and receive at the same time. The reason being is that if it tries to transmit while the receiver is active, the receiver will just pick up the transmitter's signal. And since the transmitter is almost always more powerful than whatever else the receiver is trying to pick up, you'll just get feedback. However, this does not mean 54Mbps is split into 27Mbps read/write. It can do 54Mbps read exclusively or write at most.

 

As far as the antenna count goes, both sides need to have multiple antennas for multiplexing to work.

 

However note that if your router supports different 802.11 versions, each version creates its own network, and most Wi-Fi adapters will only connect to one network, regardless of how many antennas it actually has. So you cannot, for instance, combine an 802.11a network with an 802.11g network.

[ilyas001]

2 minutes ago, M.Yurizaki said:

Wi-Fi uses what is called the IEEE 802.11 standards. The letters after that refers to a "version" or "revision" of that standard.

 

Radio signals are always half-duplex, meaning they cannot transmit and receive at the same time. The reason being is that if it tries to transmit while the receiver is active, the receiver will just pick up the transmitter's signal. And since the transmitter is almost always more powerful than whatever else the receiver is trying to pick up, you'll just get feedback. However, this does not mean 54Mbps is split into 27Mbps read/write. It can do 54Mbps read exclusively or write at most.

 

As far as the antenna count goes, both sides need to have multiple antennas for multiplexing to work.

 

However note that if your router supports different 802.11 versions, each version creates its own network, and most Wi-Fi adapters will only connect to one network, regardless of how many antennas it actually has. So you cannot, for instance, combine an 802.11a network with an 802.11g network.

but if i use csma/ca for each packet i send i will need to send back a ack right ? . so the band is at max gonna be 27 purely , i mean i m using 54 but i can only download with max 27 cause half of the passing band is used for reliability i think . also i understand that backward compatibility is the use of the same channels then the other versions but what i don't get is the max speed ?  what does it says that 802.11a have a max speed of 54 ? does it means that each channel on 802.11 a will have a max speed of 54 or the hole technologies can only use 54 mb/s max no matter how much antenna's you have , i know what 802.11 means i want more specification what does it means , 

[Mira Yurizaki]

The maximum per channel is what the maximum speed is referring to. For example, 802.11n can support up to 600Mbps, but it comes from four antennas. Also I looked at the MIMO operation, if you multiplex, they all transmit on the same channel regardless.

 

And I don't think anything before 802.11n supports MIMO.

[Guest]

1 hour ago, M.Yurizaki said:

And I don't think anything before 802.11n supports MIMO.

Correct - currently most N and AC devices will support SU-MIMO however moving forward you'll start seeing MU-MIMO (multi user)

[ilyas001]

18 hours ago, Windspeed36 said:

Correct - currently most N and AC devices will support SU-MIMO however moving forward you'll start seeing MU-MIMO (multi user)

 

ok thanks . now i have more questions , i know that each channels have there own frequency , then how will it be backward compatible if it will only work with one frequency , also i have only 14 channels with knowledge that 5ghz frequency is faster and have 23 channels how can they work together ?

thanks