Zyxel NBG5715

[rhodesengr]

Any plans to review this router here? I like the idea of external antennas because I ought to be able to improve the receiver sensitivity by upgrading the antennas. It would be very interesting to see a comparative test with the stock 2dBi antennas vs the available 5dBi antennas with respect to ultimate range. I don't need something that is super compact or looks stylish. I'll take function over form.

 

[stevech]

3dB more antenna gain is OK, but small in comparison to the path loss (many tens of dB)

 

[rhodesengr]

well I didn't want to get bogged down in a tech discussion as I was looking for review input about this router. But....

3dB is a factor of two in power. If the antennas are truly omni-directional, the power drops off with 1/r^3 (distance from the router cubed). With 3dB more antenna gain you would get the same signal at distance of 2^.333 (cubed root of 2)=1.26. So if you had a signal of -50 bdm at 50 feet with 2 dB antennas then you would get the same signal at 50*1.26=63 feet. This is a 26% percent improvement in range. As you have made the point in numerous other posts that the receiver side is equally important, the same factor of 1.26 would apply to the received signal from the client. A client at 63 feet would develop the same received signal power to the receiver with 5dB antennas as a client at 50 feet if the router had 2 dB antennas. The 1/r^3 fall-off is worst case and assumes a spherical point source. This router claims to have "smartRange" technology (phased array beaming?) If this or any other factor causes the fall off to be slower than for a shpereical point source, the 3 dB improvement would lead to an even bigger range increase.

Please keep this thread for input specific to the Zyxel router. I'll be happy to discuss/argue general radio engineering privately or in another thread.

 

[rhombus]

well I didn't want to get bogged down in a tech discussion as I was looking for review input about this router. But....

3dB is a factor of two in power. If the antennas are truly omni-directional, the power drops off with 1/r^3 (distance from the router cubed). With 3dB more antenna gain you would get the same signal at distance of 2^.333 (cubed root of 2)=1.26. So if you had a signal of -50 bdm at 50 feet with 2 dB antennas then you would get the same signal at 50*1.26=63 feet. This is a 26% percent improvement in range. As you have made the point in numerous other posts that the receiver side is equally important, the same factor of 1.26 would apply to the received signal from the client. A client at 63 feet would develop the same received signal power to the receiver with 5dB antennas as a client at 50 feet if the router had 2 dB antennas. The 1/r^3 fall-off is worst case and assumes a spherical point source. This router claims to have "smartRange" technology (phased array beaming?) If this or any other factor causes the fall off to be slower than for a shpereical point source, the 3 dB improvement would lead to an even bigger range increase.

Please keep this thread for input specific to the Zyxel router. I'll be happy to discuss/argue general radio engineering privately or in another thread.

Hmmmm. I think you might have benefited from some discussion.

 

[stevech]

reality: the 3dB benefit is almost insignificant in a link budget where the path loss from distance and a couple of walls, at 2.4GHz, is commonly 60dB or more. So give or take 3dB in this, it doesn't matter much. Esp. when you need 10+ dB of margin (excess). Of course in 802.11, the bit rate is signal strength dependent.

 

[rhombus]

Esp. when you need 10+ dB of margin (excess)

Over what, to achieve what?

3dB is 3dB is 3dB. This can indeed buy you both absolute range and effective range, the OP at least got that bit right.

The trouble is, all the rest. A little bit of knowledge, as they say! Perhaps some basics need to be revised by the OP: What's an isotropic antenna? What's an omnidirectional antenna? What's an omnidirectional antenna with gain? What's the basic calculation and law for far-field free space loss? How does real-world indoor propagation differ from this ideal? What does 3dB signal gain achieve? How does transmit beamforming actually work? How many spatial streams can it support with 3 antennas?

Then you can look at the Smallnetbuilder test locations, and have a best guess/prediction at the likely results...

 

[rhodesengr]

For the record, I bought and installed this router over the holiday. It was replacing a Linksys WRT54G. The upgrade to an N router has improved throughput everywhere downstairs. An Xbox, two rooms away, is connected on the 5GHz band. However, the signal upstairs is actually a little less than I had with the WRT54G. Internet connection was poor with the WRT54G but is nonexistent with the Zyxel. To be fair, I should add that the upstairs room was was built as an addition so there may be foil backed insulation around its walls and even the floor so I am resigned to putting an access point in that room wired back to the Zyxel.

I can't compare the Zyxel to other N routers but its worked well for over a week now. Zero reboots. I didn't do much setup other than set the SSID's and security key. Everything else is default. I did upgrade the firmware but for no particular reason. I'll just say I am very happy so far. If it had solved my upstairs problem, I would have been ecstatic.

 

[sfx2000]

For the record, I bought and installed this router over the holiday. It was replacing a Linksys WRT54G. The upgrade to an N router has improved throughput everywhere downstairs. An Xbox, two rooms away, is connected on the 5GHz band. However, the signal upstairs is actually a little less than I had with the WRT54G. Internet connection was poor with the WRT54G but is nonexistent with the Zyxel. To be fair, I should add that the upstairs room was was built as an addition so there may be foil backed insulation around its walls and even the floor so I am resigned to putting an access point in that room wired back to the Zyxel.

I can't compare the Zyxel to other N routers but its worked well for over a week now. Zero reboots. I didn't do much setup other than set the SSID's and security key. Everything else is default. I did upgrade the firmware but for no particular reason. I'll just say I am very happy so far. If it had solved my upstairs problem, I would have been ecstatic.

Sounds like things worked out well!

As far as the upstairs room, you're probably above the antenna beam pattern (as noted by the xbox having good signal two rooms away at 5GHz). Zyxel is decent gear - they spend less on marketing than the tier 1 OEM's, but their engineering group is pretty sharp.

 

[rhodesengr]

The antennas are external so I played around with the antenna directions but that didn't seem to make much difference. I really think the problem is just the added distance (it is the furthest diagonal from the router) or as I said above, there may be foil backed insulation in the both the walls and floor below. The garage is below the single upstairs room. If this is true, it would form a five sided Faraday cage and block the signal. I have a multimode Zyxel AP/repeater on order. If placing it midway between the router and the upstairs room in repeater mode does not help, I'll have to run a cable and use the repeater in true AP mode. This would really be the best solution but involves someone (not me) getting under the house to run the cable, a most unsavory prospect.

 

[sfx2000]

Is Homeplug an option? If so, then drop the WRT54G on the other end of that link as an AP...

 

[rhombus]

I have a multimode Zyxel AP/repeater on order. If placing it midway between the router and the upstairs room in repeater mode does not help

Well, put it this way: compared to an extra 3dB antenna gain, the likely 20-30dB increase in Tx and Rx gain from a repeater sure stands a much better chance...

 

[sfx2000]

Well, put it this way: compared to an extra 3dB antenna gain, the likely 20-30dB increase in Tx and Rx gain from a repeater sure stands a much better chance...

You're a meanie

At least then he'll have 10 dB of excess

 

[rhodesengr]

Homeplug is an option instead of running a cable so thanks for the suggestion but either way, I think I'll retire the WRT54G. I have a Zyxel WAP3205 on the way. I am impressed by the speeds I am getting with N and want that in the upstairs room. The main reason I want good throughput upstairs is that I have a TV up there and want to stream movies to it from a NAS I have already online. I have been streaming movies to the downstairs TV with my Xbox for over a year. I bought a WD TV Live to connect to the upstairs TV after I get the network sorted out up there. If the WAP3205 in repeater mode does work well enough I'll look at the Homeplug option instead of running cable.

 

[rhombus]

I am impressed by the speeds I am getting with N and want that in the upstairs room.

My advice: look up half duplex, then book someone to run that cable.

 

[rhombus]

You're a meanie

At least then he'll have 10 dB of excess

sounds like a party i once went to.

 

[rhodesengr]

ok. I see the Homeplug runs half-duplex to that's a disadvantage. I ordered a pair of 500 Mbs devices. If they don't give me enough throughput, I still can go the cable route. Really, I am interested to see how the Homeplug works. Its all about cost and tradeoffs like any engineering endeavor. $100 bucks for a pair of Homeplugs probably costs about the same as a long Cat6 cable and the labor to install it. Obviously the cable approach would be cheaper if I ran the cable myself. Like I said before, no way am I getting down in that crawl space.

 

[rhombus]

Actually, I meant half duplex for the repeater. The maximum throughput in your target room will be half whatever it is at the repeater position. So even if its 50Mbps at the repeater and there is no loss to the room - this only gives you 25Mbps, ie 802.11g TCP throughput - which you say you do not want.

If the initial cost of Homeplug and cable is the same, why would you opt for Homeplug? There are good reasons to go Powerline, but I don't see them here. You'll probably get anywhere from 15-85Mbps and a lot of variation, compared to up to 1000Mbps with a cable. You forgot to factor in running costs ($15 a year) and repair/replacement costs ($??) for the Homeplugs too...

However, it is great to see experimentation and action and initiative. I look forward to the writeup/results of different methods of extending range into the room.

 

[rhodesengr]

I am confused about half-duplex on the repeater. If I use Homeplug to get the signal into the upstairs room, I would use the WAP3205 as an access point, not a repeater, cabled to the home plug. Does an AP only run half-duplex? I was going to try setting the WAP3205 up as a repeater instead of Homeplug or cabling into the room but probably won't do that now.

 

[RogerSC]

If you connect an AP via a wire or powerline network connnection, you get full speed at the AP. If you use repeater functionality instead (no wire or powerline network connection, the repeater needs to listen then re-transmit), this cuts your speed in half at the repeater.

 

[rhombus]

I was going to try setting the WAP3205 up as a repeater instead of Homeplug or cabling into the room

Yes, you said this was your first step. That's what I was referring to - by repeater I did mean the device actually being used as a repeater.

Wireless is half-duplex, whether AP or repeater. But in contrast to repeater mode, if you use Homeplug or Ethernet, the router is on the wired side, not the wireless side. This is one of the reasons why a cable to an access point is preferable to using a wireless repeater.