Orientation of Airport Express

Apple's Airport Express has the mains plug as part of the case, and in
the usual application - plugging it into a wall a/c outlet - the
Airport Express hangs vertically.

I have it hanging from an a/c extension cord, and it tends to hang
horizontally.

So far, it seems to work fine in that orientation, but a lot of people
are using the same city-sponsored wifi access point, and performance has
degraded to the point that I don't get much use of it except for the
hours of 2:00am - 10:00am.

I am wondering if a better orientation of the Airport Express (it has an
internal antenna) would help me "compete" for performance.

What is the transmit/receive pattern for its built-in antenna?

It formerly got about 60-80 KB/S, with occasional bursts in excess of
90-100 KB/S. So the Airport Express is capable of that speed using
that access point.

So... would a stronger transmit/receive signal help me get better
speed? Right now, the speed will often degrade to less than one KB/S,
except for those 2:00am - 10:00am hours.

Thanks.

--- Joe

In article <none-FC071C.21444316112011@earthlink.us.supernews.com>,
Joe <none@given.now> wrote:

> Apple's Airport Express has the mains plug as part of the case, and
> in the usual application - plugging it into a wall a/c outlet - the
> Airport Express hangs vertically.
>
> I have it hanging from an a/c extension cord, and it tends to hang
> horizontally.
>
> So far, it seems to work fine in that orientation, but a lot of
> people are using the same city-sponsored wifi access point, and
> performance has degraded to the point that I don't get much use of it
> except for the hours of 2:00am - 10:00am.
>
> I am wondering if a better orientation of the Airport Express (it has
> an internal antenna) would help me "compete" for performance.
>
> What is the transmit/receive pattern for its built-in antenna?
>
> It formerly got about 60-80 KB/S, with occasional bursts in excess of
> 90-100 KB/S. So the Airport Express is capable of that speed using
> that access point.
>
> So... would a stronger transmit/receive signal help me get better
> speed? Right now, the speed will often degrade to less than one
> KB/S, except for those 2:00am - 10:00am hours.

I don't fully understand your situation. Are you also using the city
Wi-Fi service via your AE, or is your AE connected to the internet via
your own ISP and a DSL or cable modem?

If the latter, I would get a copy of iStumbler and look to see which of
the 11 wifi channels have the least load and set the AE to that channel.
This might reduce your interference. Also, some wireless phones may be
a source of interference. Does proximity of your computer (or iPad,
iPhone, etc.) to the AE make a difference?

Quite frankly, if I was in your situation and I had my own internet
connection with a DSL or cable modem, I might use Ethernet instead of
Wi-Fi. If you too are using the city Wi-Fi system, there's not going to
be much you can do. It's simply overloaded. In a place as densely
populated as New York City you might have 500 people trying to use that
node...

--
Your time is limited. Don't waste it living someone else's life.

Steve Jobs 1955-2011

In article <timmcn-C5C2D7.23582216112011@news.iphouse.com>,
Tim McNamara <timmcn@bitstream.net> wrote:

> In article <none-FC071C.21444316112011@earthlink.us.supernews.com>,
> Joe <none@given.now> wrote:
>
> > Apple's Airport Express has the mains plug as part of the case, and
> > in the usual application - plugging it into a wall a/c outlet - the
> > Airport Express hangs vertically.
> >
> > I have it hanging from an a/c extension cord, and it tends to hang
> > horizontally.
> >
> > So far, it seems to work fine in that orientation, but a lot of
> > people are using the same city-sponsored wifi access point, and
> > performance has degraded to the point that I don't get much use of it
> > except for the hours of 2:00am - 10:00am.
> >
> > I am wondering if a better orientation of the Airport Express (it has
> > an internal antenna) would help me "compete" for performance.
> >
> > What is the transmit/receive pattern for its built-in antenna?
> >
> > It formerly got about 60-80 KB/S, with occasional bursts in excess of
> > 90-100 KB/S. So the Airport Express is capable of that speed using
> > that access point.
> >
> > So... would a stronger transmit/receive signal help me get better
> > speed? Right now, the speed will often degrade to less than one
> > KB/S, except for those 2:00am - 10:00am hours.
>
> I don't fully understand your situation. Are you also using the city
> Wi-Fi service via your AE, or is your AE connected to the internet via
> your own ISP and a DSL or cable modem?
>

I'm using the Airport Express in "Join an existing network" mode, which
means it is the only means of communicating with the internet when it is
accessing that city-sponsored access point.

--- Joe

In article <none-B73C42.22191916112011@earthlink.us.supernews.com>,
Joe <none@given.now> wrote:

> In article <timmcn-C5C2D7.23582216112011@news.iphouse.com>,
> Tim McNamara <timmcn@bitstream.net> wrote:
>
> > In article <none-FC071C.21444316112011@earthlink.us.supernews.com>,
> > Joe <none@given.now> wrote:
> >
> > > Apple's Airport Express has the mains plug as part of the case,
> > > and in the usual application - plugging it into a wall a/c outlet
> > > - the Airport Express hangs vertically.
> > >
> > > I have it hanging from an a/c extension cord, and it tends to
> > > hang horizontally.
> > >
> > > So far, it seems to work fine in that orientation, but a lot of
> > > people are using the same city-sponsored wifi access point, and
> > > performance has degraded to the point that I don't get much use
> > > of it except for the hours of 2:00am - 10:00am.
> > >
> > > I am wondering if a better orientation of the Airport Express (it
> > > has an internal antenna) would help me "compete" for performance.
> > >
> > > What is the transmit/receive pattern for its built-in antenna?
> > >
> > > It formerly got about 60-80 KB/S, with occasional bursts in
> > > excess of 90-100 KB/S. So the Airport Express is capable of
> > > that speed using that access point.
> > >
> > > So... would a stronger transmit/receive signal help me get
> > > better speed? Right now, the speed will often degrade to less
> > > than one KB/S, except for those 2:00am - 10:00am hours.
> >
> > I don't fully understand your situation. Are you also using the
> > city Wi-Fi service via your AE, or is your AE connected to the
> > internet via your own ISP and a DSL or cable modem?
> >
>
> I'm using the Airport Express in "Join an existing network" mode,
> which means it is the only means of communicating with the internet
> when it is accessing that city-sponsored access point.

OK, so you are basically using your AE as a repeater for the city Wi-Fi
network. Two further questions:

1. Do you have your AE password protected so that you are the only
person who can use it (or people to whom you give the password)? If not
you should do this, using the AirPort Utility in the Utilities folder on
your Mac. Use WPA2 if possible. Otherwise you might have dozens of
people using your AE as their access, harming its performance.

2. If you use your Wi-Fi card on your computer to directly access the
city Wi-Fi hot spot, how does the performance compare to using your AE
to access it?

--
Your time is limited. Don't waste it living someone else's life.

Steve Jobs 1955-2011

Also, you might post this question to comp.sys.mac.comm since that's the
Mac networking newsgroup. comp.sys.mac.sys is nominally to discuss
issues with the operating system (although it ends up being a general
purpose newsgroup much of the time).

--
Your time is limited. Don't waste it living someone else's life.

Steve Jobs 1955-2011

On Wed, 16 Nov 2011 21:44:44 -0800, Joe <none@given.now> wrote:

[comp.sys.mac.system deleted from distribution]

>Apple's Airport Express has the mains plug as part of the case, and in
>the usual application - plugging it into a wall a/c outlet - the
>Airport Express hangs vertically.
>
>I have it hanging from an a/c extension cord, and it tends to hang
>horizontally.
>
>So far, it seems to work fine in that orientation, but a lot of people
>are using the same city-sponsored wifi access point, and performance has
>degraded to the point that I don't get much use of it except for the
>hours of 2:00am - 10:00am.

The surest sign of success is pollution. Your unspecified city
sponsored public wi-fi seems to be quite successful.

>I am wondering if a better orientation of the Airport Express (it has an
>internal antenna) would help me "compete" for performance.

No. Having a stronger signal will not eliminate mutual interference
with other users. In an extreme case, it will create additional
collisions, which will cause the other users to generate
retransmissions and retries, thus reducing the overall thruput. The
ideal situation is where everyone delivers the exact same signal
strength to the central access point, but that's not going to happen.
However, having a better than minimal signal to the access point will
help reduce YOUR retransmissions and retries, so it's worth the
effort.

>What is the transmit/receive pattern for its built-in antenna?

Essentially hemispherical. It's roughly the same in all directions.
The tiny antennas used in most such radios don't have much
directivity. If you want gain in one particular dirction, play with
reflectors or external antennas. The Aiport Express has not provision
for an external antenna, so you're stuck with a reflector:
<http://www.freeantennas.com>

>It formerly got about 60-80 KB/S, with occasional bursts in excess of
>90-100 KB/S. So the Airport Express is capable of that speed using
>that access point.

That's quite good performance from a public wi-fi system. I would not
expect that to continue as more and more users (and abusers) begin to
use it. I suggest you install a suitable sniffer on you Mac Something
and try to determine the number of other users and how much traffic
they're generating, to see if you have a chance. A typical access
point can handle about 100 users doing light web surfing and email,
about 5 users doing Netflix, and 1 user doing BitTorrent.

>So... would a stronger transmit/receive signal help me get better
>speed? Right now, the speed will often degrade to less than one KB/S,
>except for those 2:00am - 10:00am hours.

Consider yourself fortunate that you're getting 1 KByte/sec.
Oversubscription often creates disconnects.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 2011-11-17 00:44 , Joe wrote:
> Apple's Airport Express has the mains plug as part of the case, and in
> the usual application - plugging it into a wall a/c outlet - the
> Airport Express hangs vertically.
>
> I have it hanging from an a/c extension cord, and it tends to hang
> horizontally.
>
> So far, it seems to work fine in that orientation, but a lot of people
> are using the same city-sponsored wifi access point, and performance has
> degraded to the point that I don't get much use of it except for the
> hours of 2:00am - 10:00am.

Since it is hanging in such a flexible mode it should be easy to
experiment. The antenna does likely have a low gain orientation to it.

For example the the little "stick" antennas have the least gain along
their axis - so don't point it at what you want to talk to but put it
parallel to the straight line to the other system.

If it has a little 'patch' antenna then it's likely a "balloon" shape
above the patch.

There's a widget called "Airlock" at
http://www.pimley.net/projects/#airlock that may be a help at orienting
it or selecting least used channels.

--
gmail originated posts filtered due to spam.

Please forgive the top posting, it's the quickest way that I can get to
the points here.

In what follows below, Jeff, did you mean spherical, and NOT
hemispherical? If indeed hemispherical, how is that hemisphere oriented
wrt that Airport Express's case?

Also, in the below, Jeff stated
"
A typical access
> point can handle about 100 users doing light web surfing and email,
> about 5 users doing Netflix, and 1 user doing BitTorrent.
"

What kind of method/algorithm does the wifi use to distribute
transmit/receive bandwidth to the various individuals? Your reference
to Netflix and BitTorrent makes me think that somehow heavy users get
all/most of the bandwidth and other users are almost shut out. Isn't
there some sort of time-allocation slicing to divvy up the bandwidth so
that one user cannot hog all the bandwidth?

Thanks.

--- Joe


In article <gdgac7pps14lr7k9b6ucrg8mpdiitoefvp@4ax.com>,
Jeff Liebermann <jeffl@cruzio.com> wrote:

> On Wed, 16 Nov 2011 21:44:44 -0800, Joe <none@given.now> wrote:
>
> [comp.sys.mac.system deleted from distribution]
>
> >Apple's Airport Express has the mains plug as part of the case, and in
> >the usual application - plugging it into a wall a/c outlet - the
> >Airport Express hangs vertically.
> >
> >I have it hanging from an a/c extension cord, and it tends to hang
> >horizontally.
> >
> >So far, it seems to work fine in that orientation, but a lot of people
> >are using the same city-sponsored wifi access point, and performance has
> >degraded to the point that I don't get much use of it except for the
> >hours of 2:00am - 10:00am.
>
> The surest sign of success is pollution. Your unspecified city
> sponsored public wi-fi seems to be quite successful.
>
> >I am wondering if a better orientation of the Airport Express (it has an
> >internal antenna) would help me "compete" for performance.
>
> No. Having a stronger signal will not eliminate mutual interference
> with other users. In an extreme case, it will create additional
> collisions, which will cause the other users to generate
> retransmissions and retries, thus reducing the overall thruput. The
> ideal situation is where everyone delivers the exact same signal
> strength to the central access point, but that's not going to happen.
> However, having a better than minimal signal to the access point will
> help reduce YOUR retransmissions and retries, so it's worth the
> effort.
>
> >What is the transmit/receive pattern for its built-in antenna?
>
> Essentially hemispherical. It's roughly the same in all directions.
> The tiny antennas used in most such radios don't have much
> directivity. If you want gain in one particular dirction, play with
> reflectors or external antennas. The Aiport Express has not provision
> for an external antenna, so you're stuck with a reflector:
> <http://www.freeantennas.com>
>
> >It formerly got about 60-80 KB/S, with occasional bursts in excess of
> >90-100 KB/S. So the Airport Express is capable of that speed using
> >that access point.
>
> That's quite good performance from a public wi-fi system. I would not
> expect that to continue as more and more users (and abusers) begin to
> use it. I suggest you install a suitable sniffer on you Mac Something
> and try to determine the number of other users and how much traffic
> they're generating, to see if you have a chance. A typical access
> point can handle about 100 users doing light web surfing and email,
> about 5 users doing Netflix, and 1 user doing BitTorrent.
>
> >So... would a stronger transmit/receive signal help me get better
> >speed? Right now, the speed will often degrade to less than one KB/S,
> >except for those 2:00am - 10:00am hours.
>
> Consider yourself fortunate that you're getting 1 KByte/sec.
> Oversubscription often creates disconnects.

On Fri, 18 Nov 2011 18:06:23 -0800, Joe <none@given.now> wrote:

>Please forgive the top posting, it's the quickest way that I can get to
>the points here.

Top posting is evil. Please find a suitable self-inflicted punishment
and vow never to repeat this transgression.

>In what follows below, Jeff, did you mean spherical, and NOT
>hemispherical? If indeed hemispherical, how is that hemisphere oriented
>wrt that Airport Express's case?

Hemispherical. The antenna is located at the "front" of the Airport
Express, away from the power plug. It radiates equally well in all
directions, except into the wall where it's plugged in. If you dangle
it at the end of an extension cord, it will begin to more closely
resemble a spherical pattern. There are probably some holes in the
pattern in the direction of the electronics and in the up/down
direction, but for all intents and purposes, the pattern is roughly a
fat donut.

The antenna is a PIFA PCB antenna. See:
<http://www.vonwentzel.net/ABS/Dissection-Express/index.html>
The antenna is the horizontal traces on the PCB in the lower right
edge of the photo below:
<http://www.vonwentzel.net/ABS/Dissection-Express/DSCN8886-pp.jpg>
Another view, this time on the right edge:
<http://www.vonwentzel.net/ABS/Dissection-Express/DSCN8923-pp.jpg>

>Also, in the below, Jeff stated
>"
>A typical access
>> point can handle about 100 users doing light web surfing and email,
>> about 5 users doing Netflix, and 1 user doing BitTorrent.
>"
>What kind of method/algorithm does the wifi use to distribute
>transmit/receive bandwidth to the various individuals?

There are many systems running simultaneously. 802.11 prevents an
individual user from hogging all the air time by restricting the time
it can transmit data. That's partly why a 54Mbit/sec association
(connection) will only yield about 25Mbits/sec thruput. CSMA/CA also
provides for distributing the bandwidth. The "CA" stands for
collision avoidance, which does its best with backoff timers to again
prevent monopolizing the channel. Finally, the ethernet backhaul also
has a "fair share" algorithm to prevent the same problem on the wired
part of the network. If the wireless system uses QoS (Quality of
Service) to give priority to time critical packets (VoIP), that will
also redistribute the bandwidth. Most public Wi-Fi system also have
some sort of bandwidth manager which limits the bandwidth of a single
connection.


>Your reference
>to Netflix and BitTorrent makes me think that somehow heavy users get
>all/most of the bandwidth and other users are almost shut out.

Netflix is fairly good about not monopolizing bandwidth. Watching an
HD movie will try to grab about 600Kbits/sec. However, BitTorrent
will grab ALL the bandwidth it possibly can. Worse, on an
asymmetrical broadband connection, it will saturate the upstream
bandwidth acting as a server, and prevent all downloading even if
bandwidth is available by delaying ACK's. If misconfigured, it can
also kill the access point by opening too many IP sockets and threads,
running the access point out of buffer memory. It's much like traffic
on the freeway. When things get busy, EVERYONE slows down.

>Isn't
>there some sort of time-allocation slicing to divvy up the bandwidth so
>that one user cannot hog all the bandwidth?

Not with 802.11. However, there are other polling algorithms that
sequentially poll connected users for data. For a large number of
users, that's more efficient than the collision intensive method used
by 802.11.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS