Saturday, 29 November 2014

2.4 Ghz or 5 Ghz Wifi router

Their are generally 3 types of routers available in the market:

(1) Those that support 2.4 Ghz frequency band
(2) Those that support both 2.4 Ghz frequency band and 5 Ghz band but only one at a time
(3) Simultaneous dual band 2.4 Ghz and 5 Ghz router

And the price increases in that order. A common question is that which to buy ?

in my previous post, I had demonstrated that  the 2.4 Ghz network has better range (by signal strength) as seen by client but suffers from more interference which will lower throughput (considerably also). I do not have a number for this because it varies in each deployment environment. its possible in some setup the results would also reverse

If you live in a studio apartment (or single room dwelling) with clients that support only 2.4 Ghz band, and plan to retain both for while then you can go ahead and buy router type (1). It is a obsolete device and will come very cheap also. otherwise you need to decide between (2) and (3). 

I would suggest (3) as it is more extensible in nature and can be made to fall-back to (2) by switching off one of the band. Between these (2), if money is a constraint and you can live with operation in either of the two bands, then you may go for (2).


WiFi/WLAN or Wired LAN for Home Network

One of the most common confusion while deciding on Wifi Network setup is to underestimate the capacity. Typically Wireless routers are rated as 54 Mbps (802.11g ones), 150 Mbps, 1300 Mbps (both 802.11n), 1300 Mbps, 1900 Mbps, 2300 Mbps, 3200 Mbps (all 802.11 ac) and so on ...

So is a 150 Mbps WiFi network faster than 100 Mbps (ethernet network) or 1300 Mbps 802.11ac Wifi faster than a Gigabit Ethernet network ? 

The answer is practically a NO in most cases. And people assume it to be a yes, buy their routers based on this incorrect assumption, only to find later at times when they are transferring a lot of data in the LAN that their network is perhaps not as fast as wired Ethernet network. 

The first difference is that when you a buy an 8-port gigabit Ethernet switch it has a switch fabric inside and each Ethernet port can theoretically switch 1 Gbps. So a theoretical max of 8 Gbps is the overall switching capacity (each port can send/receive 1 Gbps simultaneously.  In contrast when you buy a 1300 Mbps switch, the maximum theoretical router capacity is 1300 mbps (i.e. sum of bandwidth of all clients put together). I guess the answer to the above question is clear right at this stage. This confusion for buyers is caused more by the marketing label.

The  second difference is caused by interference. Wired network suffer less from interference if the cables are properly shielded from other cables and power lines which means each circuit can practically work very close to 1 Gbps or 100 Gbps  limit of the switch (as long as both ends support similar speed and cable quality (rated speed) matches the network speed. This means a wired network will be more stabler and reliable in throughput. In contrast, the Wireless network suffers from interference from other devices like microwave and neighbouring networks (in an dense urban apartment or layout). It is also heavily effected by the attenuation offered by household items, brick walls, etc.

Here's how my current Home wifi environment (in an apartment complex) looks like:


 Above is the 2.4 Ghz band which looks extremely congested (the J602-XXX is my home Wifi network with the private and guest network). In contrast here is 5 Ghz band (my network is the only one  around on the 5 Ghz band):


Of course the 5 Ghz band suffers from weaker range and need for client to support 5 Ghz (a rarity in  older but still not entirely obsolete devices). More on this trade-off later.  And also notice the signal strength I am getting (-45 dbm) right to the router. In my room, for which the wireless signal has to cross ONE bedroom (2 solid but thin brick walls), this falls to -55 dbm (4 out of 5 bars or close to acceptable level).


Let the signal cross two rooms (or walls) the result is quite pathetic. 


The 2.4 Ghz network signal strength falls  below -70 dbm while the 5 Ghz  strength falls below -80dbm. If I had a bigger flat with one more additional room probably the 5Ghz signal would have been completely lost in the next room.


The above figures (all captured with WiFi Analyzer App on android) also show that 2.4 Ghz signal strength is consistently better than the 5 Ghz ones and therefore has more usable range.


Refer the table below to judge how serious the signal strength attenuation is:

Signal Strength  Qualitative Assessment Required for
-30 dBm Max achievable signal strength. The client can only be a few feet from the AP to achieve this. Not typical or desirable in the real world. N/A
-67 dBm Minimum signal strength for applications that require very reliable, timely packet delivery. VoIP/VoWiFi, streaming video
-70 dBm Minimum signal strength for reliable packet delivery. Email, web
-80 dBm Minimum signal strength for basic connectivity. Packet delivery may be unreliable. N/A
-90 dBm Approaching or drowning in the noise floor. Any functionality is highly unlikely. N/A

Data Courtesy: https://support.metageek.net/hc/en-us/articles/201955754-Acceptable-Wi-Fi-Signal-Strengths.

And BTW, my router is a 200USD+ Asus RT-AC68U with 3 antennas, beam-forming support, etc. Its no slouch and one of the best around.

So if your client is very far from router and signal has to cross many walls from  client to router, expect big trouble. Ofcourse you can reduce this to some extent by using a Wifi repeater at less than half the rated bandwidth of one client or trying to relocate the router at central position in house where all client see a better signal (if at all this is feasible).

And don't think you can get a better signal by increasing the Transmission Power (Tx) of Router. Wifi communication is bi-directional. You can make yourself heard in every corner of a non-empty large hall/lecture-room by increasing you are speaking volume (shouting, screaming, etc), but that's no guarantee that you can hear everyone. Every also has to increase their volume to make themselves heard to you. And Mobile devices usually transmit at lower power to conserve battery, making them unusable at slightly longer distance from router.


To summarize,

(A) Speed, throughput & range of wireless networks will drop even with small distance from router which is not the case with a Wired LAN switch
(B) Wireless LANs suffer from interference from neighbouring networks and other cordless or microwave devices typically encountered in homes which is not the case with wired LAN
(C) Wireless signals get attenuated strongly by brick and mortar walls which is not the case
(D) A Gigabit Ethernet router/switch has all ports that can work on 1 Gbps duplex, but a xxx Mbps router (access point) does not guarantee that each client can work at that speed (its just the sum of all speeds is theoretically limited by this number)
(E) The future of wireless is 5 Ghz which will suffer less from interference, but will offer even more decreased range than 2.4 Ghz wireless.


So that's it.  Today's (2014 end) wireless network can offer performance and throughput nowhere near the wired networks. This is a practical fact. You should try to put static immovable devices like desktop computer, NAS, IP camera, Television STB on wired networks for maximum performance, throughput & reliability while movable devices like tablets, smartphones and laptops etc can use your Wifi network. And for devices which do need to transfer much data (like network enabled consumer home appliances like refrigerator, Washing machine, etc) the choice does not matter (and probably Wifi is better because it frees the appliance from the problem of being near a Wired LAN port and messy cabling). 

Their are of course many normal users who do not have large number of Wifi Clients or high data transfer requirements within LAN, and comparatively slower broadband connection (<20 Mbps) and they should be fine with having a Wifi Network only. Then also their may be a limitation to the range of Wifi.

Thursday, 24 April 2014

Are we ready for 4K video

We are now getting into a bigger Video streaming problem. We are moving to 4K from 1080p.

1. In India, we can see 4K LED TVs in most electronic stores. 
2. Smartphones and Tablets are starting to incorporate 4K resolution displays (JDI is making them). 
3. Smartphone camera modules are getting the ability to shoot 4K videos which means a lot of user generated content.
4. Youtube supports 4K videos and Pirated Content on torrents are appearing in 4K.
5. We are seeing Routers that support 1300 Mbps 802.11ac and 600 Mbps 802.11n in the relatively uncongested 5 Ghz bands as well as smnartphones, dongles and PCIe Cards supporting 802.11ac

That means content generation, distribution, consumption & WLAN infrastructure infrastructure is ready for 4k. But the missing picture is the WAN network. 4K digital video files are typically two times bigger than 1080p.  Are the Broadband access networks  ready for 4K video streaming or even downloads ?

Atleast in India, the broadband infrastructure, tariff and plans are not geared to handle 4K at all. Especially when the content is OTT for which no one seems to be ready to pay (neither the service provider, nor the subscriber).  

What use then is downloading 4K content or buying 4K screens of any form factor ?

Thursday, 17 April 2014

How to select a Fixed Broadband connection in India ?

The time of unlimited broadbad is over. Initially when the broadband connections where launched their was a speed (128 Kbps/256 Kbps/512 kbps)  but no FUP limits. While these speed were defintely not broadband, content was also no HD and so it was acceptable. Today most content is 1080P HD or even 3D (2K/4K in future). Access speed have gone up to 8-25 Mbps in many cases. But the dreaded FUP limits have come up based on how much you pay and after this limit is reached the speed falls to 512 Kbps usually which isn't broadband in today's times by any stretch of imagination. This is how most ISPs operate. In my opinion, these are the deciding factors for selecting an unlimited plan

(1) Speed - The higher pre FUP limit and the higher after FUP limit, the better. This has to be measured on site not on what the manual promises as sometimes the operator promises high *upto* speeds, but with increasing subscribers and less infrastructure, he can't honor his promise.
(2) FUP limit - The higher the better
(3) Reliability - Extremely important. If a network is not available most of the time, then you can't use your high FUP limit or fast speed. The equipment used should be good and the network mangement better so that downtime is minimized. Airtel fares the best in the reliability factor in my home location. But I am willing to trade in a little bit of downtime in favour of extra FUP and speed at a given cost. But only a little ...
(4) Cost - It should fit your budget or you should be willing to pay what operators ask for what you desire. if all other factors are similar or acceptable, cost should be the deciding factor.
(5) Coverage - Fixed broadband has severe coverge limitations based on where the operator is able to spread his network. All the above is no good, if it can't reach you at you location. This is a constraint but keeps changing every 3-6 months as networks and players expand.

To decide on (1) and (2), you need to consider what is your use case. For small bandwidth hog applications like web-browsing, Mails, Social Networking, VoIP, Instant Messaging, PC/Laptop/tablet/Mobile app updates or downloads, the speed does not matter so much beyond a threshold limit. Maybe 512 Kbps (or post FUP limit) is acceptable. But cases like streaming video (Youtube, Netflix, BigFlix, Eros, etc for SD content), you may need 1 Mbps speed. You may needs 2 Mbps miniumum for 720 p streaming and 4-8 Mbps for 1080p HD. For downloading movies (big files) their is no mimimum speed. The higher the better as you download is likely to complete faster (you do not want to wait for an eternity for it to complete and then watch it. rather you could just rent a DVD or Blueray which will be delivered to you in a day). FUP will limit how much of this SD/HD video content you can watch but may have no perceivable impact on on the small bandwidth hog applications.

And I feel day by day their is no incentive in customer loyalty. The ISP who gives the most acceptable package of (1)-(4) is the one who should get my business. I have been a loyal customer of airtel broadband for 10 years, but right now I feel they are gettiing expensive for what they offer and I am tempted to look at other providers who could give me a better speed and higher FUP with little downtime [Airtel is 0 downtime, but I think I can barter the first two factors with a little downtime. I am an Internet leech ;-))].

No FUP anyone ???


Sunday, 13 April 2014

Hooking Network storage on to ACRyan PlayOn! Mini 2

One of the very major decision that I made for my home network was to centralize the data tier in a NAS, the objective that it can provide me reliable stoarge accessible on any device, anytime and possibly from within anywhere inside and outside the home network. It could be expanded based on need without having to upgrade the access devices. The data centralized can include:

(1) Data rlevent to computers (Windows, Linux or Mac)
(2) Music
(3) Movies, Documentaries, DVDs, CDs, etc
(4) Our Photographs and Videos shot through digital cameras/camcoders/smartphones
(5) Books, Important papers, documents etc.
(6) Anything else 

For video, one key access device is the STB streamer serving the Television. In my case I already have invested in an AC Ryan PlayOn! Mini 2 (without HD) for my little daughterto watch her bursery rhymes, animations films and TV series. It also has done a perfect job with any .MKV, .Avi, .ts that we have thrown at it. I find this cheaper than an HTPC.

One key issue i faced with the streamer is whther to connect it to the router using WiFi or Wired Connection. In my present temporary residence, I do not have a wired network in place and hence I am forced to use WiFi. I faced many issues:

(1) First the number of dongles supported is very few (Realtek based 802.11n draft version only). ACRyan does not maintain a HCL for dongles and offically support only their dongles (ACR-WN10001 and ACR-WN10002). To be one the safe side, I decided to buy the official ACRyan dongle (ACR-WN10002). It would be a logical decision for most

(2) The problem with ACRyan dongles is that they support only 802.11n and the 2.4GHz frequency band. The 2.4 Ghz band suffers from interference from other networks in the aprtment effecting the throughput. Even though rated at 300Mbps downlink and 150 Mbps downlink, I am able to connect at a speed of only around 20 Mbps MAX with any 802.11n or 802.11ac router. I have no g or AC clients on the network. My other 5 ghz 802.11n clients like PCs connect at a solid 450 Mbps to these routers, but the ACRyan dongle is stuck at only 20 Mbps. ACRyan does not seem to make a 802.11n dongle that supports the 5 GHz band. This poses two problems:

(a) Some high bit rate 1080p movies won't play properly at times and their is frame choppinness. 
(b) When i forward or rewind, the progress is very slow even though i am forwarding at 16X/32X. The feature is practically unusable.

It could be the draft-n driver in the streamer or the interference (likely) on 2.4 ghz bands. I generally observed that the access bandwidth of 5 ghz clients are twice or higher than 2.4 ghz clients on PC. And all these devices are in the living room within a 5m radius from the router.

However, to my surprise, these two problems are solved if I connect the streamer STB to the router using a LAN cable or play from a USB connected disk. I am forced to think that if I had 450 Mbps 3-antenna 802.11n client working on 5 GHZ band, then atleast my access speed would have been much higher and I could have avoided these two issues. Right now I have no solution on WiFi for the Mini 2.  This is a direct feedback to the folks at AC Ryan for their next series or future firmware/dongle-device upgrades for the Mini 2 streamer. Better build the fastest WLAN connectivity into the device or supported dongle and perhaps reserve space to upgrade to future technology driver.

A warning to other People buying streamers without disks or intending to stream content from a file server need to care about the bandwidth between the data source and streamer. An excellent streamer  (ACRyan PlayOn! mini 2) somewhat let down by sub-standard wifi connectivity ...

UPDATE: One possible solution for such problems due to poor network connectivity could be the use of a small memory (say 32 GB or so plugged on the USB port) as a frame buffer cache. Some CPU cycles could be used to copy part (even 100%) of the data  to the disk at the beginning, while the player starts playing from disk, part of the CPU cycles are used to continue the copying to that temporary storage. the amount of the data to be copied could be based on the gap between the required streaming bandwidth for the file and the actual (10% anyways to account for Wifi connectivity issues). This might overcome the frame choppiness in most cases.


Friday, 15 November 2013

why I am no longer interested in 802.11n Home WLAN networks

Recently i installed a file server (NAS) at my home. This was FreeNAS 9.1.1 based. And immediately I ran into a performance issue with a test network. The test network is 802.11n Wifi spun by a Linksys WRT 320N router. Its not MIMO and runs at around 150 Mbps (theoretically max.)

To my shock the data transfer speeds to my FreeNAS server (which is amply powered in CPU and RAM) was just 6 MB/s write. I checked up that the client desktop was hardly loaded while doing transfer and the server was hardly using 1% CPU. The suspicion went to the network and I checked that my WiFI link on client machine (the file server was wired with a 100 Mbps cable to the router) is just 104 Mbps. The throughput of WiFI link was just 6X8 = 48 MBPs.

I got a couple of CAT6 ethernet cables and wired both the client and file server to the router. And sure enough my throughput jumped to more than 100 MB/s.  16+ times faster. Around 130 MB/s is my SATA disk to another SATA disk transfer speed in client machine. So I assume that if remote disks on my FreeNAS server are mounted and used for storage and data, then their would hardly be a performance penalty observed. Personal cloud may just work beautifully and reliably

I was planning to buy a 802.11n MIMO router which can give me 300-450 Mbps, but I don't think its going to suffice my needs with multiple TVs, smartphones and PCs accessing the common storage area. Definitely I want to offload all my fixed devices to GbE whereas mobile devices will be attached to WiFI (the best I can get). My conclusion is that WiFI is slow and unstable. The 2.4 GHz band also seems to be unstable in the sense that there are frequent changes in link speed which makes the WiFi links unstable for streaming video. i can occasionally observe choppiness of frames.  Heard that the 5 GHz band is less crowded and 802.11ac is using only the 5 GHZ band. 1080p has gone to 4K and I think I need all the speed I can get to reasonably future proof my network from content bloat. Though they would go cheap now, it may not be prudent to invest in 802.11n anymore. The new 802.11ac (5G Wifi) devices to be released in 2014 are expected to reach speeds of 1.3 Gbps and I think that's what I would want now.

And yah, FreeNAS seems to be damn cool for NAS applications. Glad I ditched embedded fixed bay nas vendors and chose freeNAS instead. Superior in every way once the initial pain of selcting hardware and installation is through.

Thursday, 25 April 2013

What I think my new home network should be like

I live in India. Homes are just getting smart, but only in the super premium housing sector. I haven't arrived as yet (and possibly won't in atleast the near future) and therefore i am stuck with an apartment where I have to be the DIY guy again ;-)). And I before i go ahead and buy gear, I need to decide what's best to buy.

The first part is that today all devices and appliances one keeps at home are getting WiFi (or in some cases Ethernet) enabled. The application is usually to exchange some information with other devices/appliances or services in the Home LAN (for eg, smartphone beaming to the HDTV, IP Camera streaming to a PC or file server, etc) or the Internet (Refrigerators ordering groceries in future, water purifier placing a service request for filer change once it detects its life is over, Pc browsing or downloading, set-top ox streaming videos from internet or downloading titles etc). And do that we need a very decent, high performing network to start out with.

So how do we do this ? We have gigabit Ethernet  today as well as 802.11 a/b/g/n/ac and which of these we use ? Ethernet is faster, more stable, but requires a lot of cabling at fixed points making it inflexible. WiFi is also fast these with MIMO technology but still throughput is expected to be less, is prone to interference and signal attenuation by walls and household objects. so how do we call the dice ?

I establish two  principles for my case:

(1) We use Gigabit Ethernet for devices and appliances that are fixed in location within the house (TV, PC, File Server, Consumer appliances, IP cameras, etc)
(2) We use WiFi for devices that need mobility within the house (like smartphones, tablets, Laptops, etc). And this would also cover appliances that may not support Gigabit Ethernet but only WiFi (A very likely scenario for consumer appliances of the future)

Clean. Since I have the flexibility of deciding my LAN ports, I can go for this type of setup. People who do not have this option may have to install WiFi Routers and repeaters (maybe more than one)

And to achieve some flexibility I decide that every room (living, dining, Bedrooms, Kitchen, utility, toilets and servant quarters will have atleast one LAN port, sometimes more based on what appliances I want to place. This also ensure that the highly bandwidth intensive streaming inside house i.e. file server to TV, and IP camera to file server PC stays on the Wired network and doesn't load the wifi. I hope this will make these applications jitter free. So for me Ethernet is not dead. Infact it is the preferred network and I stay fixed AFAP.

Equipment wise, I will go for

  1. An 802.11 n MIMO router (Asus RT-N66U)  or even an ac router (RT-AC66U). Basically whatever is the fastest on the market and one that matches my wifi Client. Additionally some range extenders if required (unlikely for my case)
  2. Possibly a 16/32 port LAN switch or router. Required to support so vast number of Ethernet  ports. I suspect their is none available for consumer market and this has to be a SOHO or Enterprise gear. Maybe this would be multiple 4/8 port ones (consumer oriented) based on what type of networks I want to isolate.
More on this later.