w******t
发帖数: 241 | |
X*****r
发帖数: 2521 | 2 no
【在 w******t 的大作中提到】
: 是不是跟手机一样上下行链路的频带分开了？
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z*****n
发帖数: 7639 | 3 No, the same frequency.
802.11 uses CSMA scheme to schedule the transmissions.
【在 w******t 的大作中提到】
: 是不是跟手机一样上下行链路的频带分开了？
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w******t
发帖数: 241 | 4 802.11 和 802.15.4频谱部分是重叠的。有什么办法避免两者的竞争吗？
【在 z*****n 的大作中提到】
: No, the same frequency.
: 802.11 uses CSMA scheme to schedule the transmissions.
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z*****n
发帖数: 7639 | 5 If you can manually select the channels, this is
a trivial problem.
【在 w******t 的大作中提到】
: 802.11 和 802.15.4频谱部分是重叠的。有什么办法避免两者的竞争吗？
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i*****f
发帖数: 578 | 6 Then in infrastructure mode. The AP needs to forward all the traffic in the
WLAN, using the same contention scheme? Isn't it unfair for the AP?
【在 z*****n 的大作中提到】
: No, the same frequency.
: 802.11 uses CSMA scheme to schedule the transmissions.
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X*****r
发帖数: 2521 | 7 that is why it is called AP
others just nodes
enjoy a decent and high title and pays off
the
【在 i*****f 的大作中提到】
: Then in infrastructure mode. The AP needs to forward all the traffic in the
: WLAN, using the same contention scheme? Isn't it unfair for the AP?
|
i*****f
发帖数: 578 | 8 But what it pays off is not its own data. AP is forwarding other nodes data
in the WLAN.
So i think AP's accessing to the channel should be garanteed, but it SEEMS
AP doesn't get any priority to its subscribers in the WLAN.
Is this the trueth or I misunderstand something in the standard???
【在 X*****r 的大作中提到】
: that is why it is called AP
: others just nodes
: enjoy a decent and high title and pays off
:
: the
|
X*****r
发帖数: 2521 | 9 true
data
【在 i*****f 的大作中提到】
: But what it pays off is not its own data. AP is forwarding other nodes data
: in the WLAN.
: So i think AP's accessing to the channel should be garanteed, but it SEEMS
: AP doesn't get any priority to its subscribers in the WLAN.
: Is this the trueth or I misunderstand something in the standard???
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c****n
发帖数: 21367 | 10 in most of the time, AP doesn't have its "own" data...
the most commonly seen AP is a wireless router... how much traffic
itself will generate?
data
【在 i*****f 的大作中提到】
: But what it pays off is not its own data. AP is forwarding other nodes data
: in the WLAN.
: So i think AP's accessing to the channel should be garanteed, but it SEEMS
: AP doesn't get any priority to its subscribers in the WLAN.
: Is this the trueth or I misunderstand something in the standard???
|
|
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i*****f
发帖数: 578 | 11 I didn't mean that it's not fair for AP ITSELF.
See, suppose the WLAN is very heavy-loaded. And all the traffic's
destination is in the WLAN (i.e., other nodes in the WLAN).
If the AP's chance to access the channel is the same as a normal node. It
seems that AP will never be able to forward all this traffic.
【在 c****n 的大作中提到】
: in most of the time, AP doesn't have its "own" data...
: the most commonly seen AP is a wireless router... how much traffic
: itself will generate?
:
: data
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c****n
发帖数: 21367 | 12 what's the unfairness then? everyone needs the AP forwarding
both the data and ACK
【在 i*****f 的大作中提到】
: I didn't mean that it's not fair for AP ITSELF.
: See, suppose the WLAN is very heavy-loaded. And all the traffic's
: destination is in the WLAN (i.e., other nodes in the WLAN).
: If the AP's chance to access the channel is the same as a normal node. It
: seems that AP will never be able to forward all this traffic.
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X*****r
发帖数: 2521 | 13 he/she means the unfairness between AP and clients
【在 c****n 的大作中提到】
: what's the unfairness then? everyone needs the AP forwarding
: both the data and ACK
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X*****r
发帖数: 2521 | 14 as I told you, it is the DESTINY of the AP
like pigs, most of them got food since they will be your food someday
unfair, isn't it?
APs are like pigs, their lives are predetermined, i.e., serving people, when
they are created/breeded
it is unfair, i agree...
【在 i*****f 的大作中提到】
: I didn't mean that it's not fair for AP ITSELF.
: See, suppose the WLAN is very heavy-loaded. And all the traffic's
: destination is in the WLAN (i.e., other nodes in the WLAN).
: If the AP's chance to access the channel is the same as a normal node. It
: seems that AP will never be able to forward all this traffic.
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i*****f
发帖数: 578 | 15 ok, forget the 'fairness' issue. I used an impropriate word.
How to explain/solve the scenario I described (assumed) in the previous post?
or that's the actuall case.
P.S., i'm a he :)
【在 c****n 的大作中提到】
: what's the unfairness then? everyone needs the AP forwarding
: both the data and ACK
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X*****r
发帖数: 2521 | 16 that is the way it is
and that is the bottleneck of WLAN
post?
【在 i*****f 的大作中提到】
: ok, forget the 'fairness' issue. I used an impropriate word.
: How to explain/solve the scenario I described (assumed) in the previous post?
: or that's the actuall case.
: P.S., i'm a he :)
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i*****f
发帖数: 578 | 17 Yes, bottleneck, that's what i what to say, hehe
【在 X*****r 的大作中提到】
: that is the way it is
: and that is the bottleneck of WLAN
:
: post?
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c****n
发帖数: 21367 | 18 it is simply true you can physically jam a WLAN using a laptop only
what's the problem?
post?
【在 i*****f 的大作中提到】
: ok, forget the 'fairness' issue. I used an impropriate word.
: How to explain/solve the scenario I described (assumed) in the previous post?
: or that's the actuall case.
: P.S., i'm a he :)
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X*****r
发帖数: 2521 | 19 how？
【在 c****n 的大作中提到】
: it is simply true you can physically jam a WLAN using a laptop only
: what's the problem?
:
: post?
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i*****f
发帖数: 578 | 20 no you can't jam a WLAN with a laptop if it uses PCF
【在 c****n 的大作中提到】
: it is simply true you can physically jam a WLAN using a laptop only
: what's the problem?
:
: post?
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|
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c****n
发帖数: 21367 | 21 keep sending signals
【在 X*****r 的大作中提到】
: how？
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c****n
发帖数: 21367 | 22 keep sending signals
【在 i*****f 的大作中提到】
: no you can't jam a WLAN with a laptop if it uses PCF
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i*****f
发帖数: 578 | 23 PCF
【在 c****n 的大作中提到】
: keep sending signals
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X*****r
发帖数: 2521 | 24 no
you can not capture the channel for ever
everyone with the same traffic load should have stochastically equal
opportunity
【在 c****n 的大作中提到】
: keep sending signals
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c****n
发帖数: 21367 | 25 who cares your rts/cts? keep sending
【在 i*****f 的大作中提到】
: PCF
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i*****f
发帖数: 578 | 26 ok i got you. 很好很强大 @@
【在 c****n 的大作中提到】
: who cares your rts/cts? keep sending
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c****n
发帖数: 21367 | 27 what if the laptop just ignore the rules?
【在 X*****r 的大作中提到】
: no
: you can not capture the channel for ever
: everyone with the same traffic load should have stochastically equal
: opportunity
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X*****r
发帖数: 2521 | 28 well
if the attacker does not follow 821.11
yes, you are right
but this is the problem of CSMA/CA
【在 c****n 的大作中提到】
: who cares your rts/cts? keep sending
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c****n
发帖数: 21367 | 29 :) if everyone's in csma/ca, no problem even if in dcf
because everyone's contention windows would grow up
and the maximum contention windows size corresponds to the
maximum number of nodes allowd to associate with one AP
【在 X*****r 的大作中提到】
: well
: if the attacker does not follow 821.11
: yes, you are right
: but this is the problem of CSMA/CA
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z*****n
发帖数: 7639 | 30 There are two versions for AP:
802.11 DCF and 802.11PCF
in the original mode AP acts exactly the same as other
nodes(mobile stations), in this case AP is potentially
a bottleneck of the system.
802.11PCF is aimed to solve this problem. In PCF, AP
usually waits a less interframe gap than other nodes,
thus giving AP an advantage to catch the channel.
the
【在 i*****f 的大作中提到】
: Then in infrastructure mode. The AP needs to forward all the traffic in the
: WLAN, using the same contention scheme? Isn't it unfair for the AP?
|
