Wireless Networks - Evolution to 5G !!!

A famous quote read, “Technology must be like Oxygen: Ubiquitous, necessary and invisible.” Which exactly describe today’s wireless networks.

Wireless networks are the oxygen necessary for today’s vast global communication infrastructure. They are the platform over which the entire Digital ecosystem is built. Wireless devices today are capable of doing pretty much everything from making a phone call to using the internet and running applications. Wireless networks today are the backbone of user as well as business communications.

Wireless networks use Radio Frequency technology commonly referred to as RF. The RF signal is an electromagnetic wave that today’s smartphones and computers can detect and connect too. 

There are 2 main components of wireless networks:

-          Access Network

-          Core Network

Access Network: An access network is the invisible user network that connects subscribers or users wirelessly to a particular service provider and, through the carrier/operator network, to other networks such as the Internet. Users connect to the access network via Access point. The access point can be your WiFi Access point or nearest Verizon telecommunications tower (base station).

Core Network: A core network, is the central part of a telecommunications network that provides various services to customers who are connected by the access network. Services such as ability to make a phone call, browse internet, using social media apps such as FB, Twitter etc.

The figure shows the evolution of Wireless Networks from 1980’s to present day i.e. from 1G (1^st Generation) to 4G/5G Era. It all started with basic voice service deployed on analog phones in 1980’s with maximum rate of 2Kbps. Analog communication meant taking human voice and translating it to electronic pulses. Over the years the communication industry has witnessed one of most historic & iconic transformations from analog to digital that enabled services like Video Conferencing and Gaming possible. Digital transformation involved breaking down signal into binary format of 1’s and 0’s.  At every stage the telecommunications infrastructure evolved with providers like Verizon at the forefront of research and development to further the cause of technology. Innovations in wireless space have facilitated creation of popular devices such as iPhone and Samsung Galaxy S7 and services such as Video calling and social media platforms to flourish. 

Wireless evolution has changed the way how business is carried out and has enabled development of several use cases which were unthinkable even a decade ago.

Different Approaches for Voice over LTE ?

There may be different approaches by different mobile operators (read Verizon and ATT) for voice over LTE solution. Primarily this has to do with their LTE deployment strategy. AT&T will go with a phased approach wherein they will deploy LTE in certain markets and cover the rest with HSPA+. This seems to be their strategy which makes sense since HSPA+ also can match ractical UL/DL speeds that LTE provide.

Tmo just announced their HSPA+ rollout in few cities which AT&T should like. So AT&T might adopt a Circuit switched over HSPA approach for 2-3 years before they decide to overlay LTE with nationwide footprint.

Verizon on the other hand is overlaying its current CDMA network with an LTE. So seem likely to adopt IMS core for their LTE implementing VCC.

I read an interesting article about a possible third approach for LTE voice .. and that Dual Radio with single SIM . Verizon surely seems to be using this with Thunderbolt, which is bound to save them some CAPEX (in near term) for not implementing IMS core. But going forward they will certainly upgrade to IMS core to incorporate burgeoning APP world.

For Sprint only time will tell how will they rollout LTE. But they certainly can take a leaf out of this Malaysian operator :)

Voice Over LTE

LTE being a packet based technology; there have been ongoing discussions about Voice implementation over LTE. This is going to be crucial as operators would want just one network to be maintained to reduce their CAPEX and OPEX. There have been quite a few solutions being pondered upon in the 3GPP community.

One way is the CS fallback mechanism to address this. By CS fallback they mean that for voice LTE will handover the call to 2G/3G networks. This is done by MME registering the device with the 2G/3G networks and acting as SGSN communicating with MSC for voice signaling. This will ensure that the voice quality is maintained as of today, but this would also mean that if an existing packet data call is in progress, then it might get suspended or handed over to 2G/3G networks. I am not sure is this will be good idea since earlier generation networks will not have the bandwidth and the capacity to support LTE multi-media applications.

I read a paper about CSoHS (Circuit Switched over HSPA+) . This explains about how HSPA+ radio bearers will be used to carry voice traffic but core used will be CS core.
This can be done via software upgrade on UE as well as RNC. This would add de-jitter and time warping mechanism to ensure smooth voice quality. I hope this can be further extended to LTE, which is approach pursued by VoLGA which stands for Voice over LTE via Generic Access (Thanks to Steve for clarifying this!!). The difference between 2 approaches is avoiding the fallback to legacy networks and also using high capacity radio bearers. Also user not be required to suspend/handoff his data call.

Though these above approaches sound good for now, they would still require different networks to be maintained. Going further, IMS will have an important role to play as it can support end-to-end voice over IP services with call signaling and switching functionality required for voice. It also supports Voice Call Continuity (VCC) that can enable gradual deployment of VoIP.

RevB Knocking on Carrier's Doors

Lately there has been a lot of buzz about LTE. Last week at Mobile World Congress 2009 in Barcelona, major wireless carriers like Verizon, Vodafone, AT&T, T-mobile announced plans to go with LTE as their next generation 4G technology. Verizon went even a step further to detail their vendors, commercial trials and deployment plan. So LTE looks all set to hit the trials by late 2009/early 2010.

Having said that I feel LTE is alteast 3 years away from commercial readiness. And here's why. If we take a deeper look into Verizon earnings call their CAPEX spending for 2008 was almost the same as their previous year. LTE deployment would require billions of dollars in CAPEX. Considering the current market economy, it is hard to imagine Verizon going with an aggressive rollout. So as per Verizon CTO Dick Lynch, we should see LTE rollout in 2011. But I believe it will be more of phased approach with all markets covered by 2013. We should see other carriers also follow the same approach.

LTE boasts of download speeds of about 34Mbps (I would assume it will be 10-15Mbps theoretically). LTE will be a platform for all data centric applications requiring higher speeds in the order of 8-10 Mbps. VoIP should also take off. But the phased approach in LTE deployment would require current 3G networks to support higher speeds. EVDO RevA can only support upto 3Mbps, though theoretically its must less than that (700Kbps-1Mbps).

Here is where EVDO RevB steps in for the 3GPP2 camp. For carriers like Verizon, it should only be a software upgrade not requiring much additional spending. 3 carrier RevB can support downlink speeds of upto 9Mbps and uplink speeds of upto 5Mbps. Qualcomm also announced availability of MSM8960 chipset supporting both LTE and EVDO RevB at MWC 2009. So if carriers decide to roll out RevB along with phased out LTE approach, they should see availability of dual mode handsets supporting LTE/RevB handovers with seemless mobility. This would enable applications designed for LTE getting traction soon resulting in rich user experience. Nobody wants their video conferencing session being closed just because they moved from LTE to EVDO network.

Now RevB makes even more sense to Sprint. The beleaguered carrier just lost 1.4M subs in Q4. WiMax even though being a good technology with time to market advantage, its facing the same destiny as EVDV. So even if WiMax is prevalent, I see it more of a backhaul solution than 802.16e. Moreover its now Clearwire's headache. So now Sprint is left with its EVDO RevA network. Their rival Verizon is moving to LTE. So they need a network that can compete with Verizon in terms of speed, supporing data hogging applications. And year on year there has been consistent increase in data usage. Cisco even predicts data usage going up with video services accounting for 64% of mobile traffic by 2013. Surely if the carriers are to support around 5GB demand for data per month they ought to have network that can meet the demand. With EVDO RevA I do not see that happening. Also the incremental cost of deploying RevB will be much less.

I think both Verizon and Sprint should go for RevB in order to get maximum out of their current 3G networks before we see 4G taking over. 3GPP camp will also do the same with Tmobile, AT&T upgrading their networks to HSPA + coupled with phased LTE rollout.

My Coolest Possession So Far:

As most of you must have guessed it already, its the one and only .... iPHONE 3G!! After waiting for like close to 4 hours in line on saturday, the next day after the iPhone release on July 11th, outside apple store, there I was holding it and beaming with joy !! I tell you even waiting in the line was soo much fun. Everyone was upbeat and we all were discussing its GUI, the apple store with plenty of applications already out etc etc. Seemed like everyone thought this was the coolest thing ever (including me..and I still think that way :) ).

After that, I have been playing with the device ever since. Have hardly used my laptop for web surfing, emailing, watching videos and the all the stuff I used to do at home. After testing the device for what its built for, I thought I should make a note of the plusses and minuses.

Thumbs Up:

GUI : Obviously its got the best GUI i have seen on any phone till now. Its so cool and user friendly. Touch screen is very responsive thereby making the navigation fast. I think only Cupertino (read Apple) can built something like this.

Web Surfing: Apple has done a great job here. The web layout on the iphone is great with all the content displayed as if it were on any home PC. So browsing on iphone is fun and more importanly without stress on eyes. The layout changes as you tilt the iphone making it even more adaptive.

Maps along with GPS: This is where the 3G iphone betters 2G one. With the inbuilt GPS, it easy to find the current location. Even if there is no in-building coverage, it uses WiFi to locate you correctly. Also the satellite and the hybrid modes along with the real time traffic conditions makes it overall a cool and usable feature. Also with AT&T navigator, you can subscribe to unlimited turn by turn voice directions for $10/month.

Calculator: For geeks, there is scientific calculator build in. When you open the app, its a normal layout, but parallel to the ground, it turns into a geeky layout with all the sines and cosines :). But i think its a very useful tool for engineers like us.

Call quality: The speaker voice quality is good. Also iphone picks up the signal decently, I wouldnt say its the best in this as other 3G phones have better signal reception.

Battery Life: Apple has done a very good job with this one. With the normal claims of about 6.30 hrs on 3G (voice + data), which I couldnt try as network near my area is 2G :(:( , even on WiFi its lasts about 3-4 hrs, which I think is very good considering 802.11 hogs the battery.

iPhone Applications: I am amazed to see soo many applications already out on the apple store, with not even a week since it released last friday. Some of the applications like Jots, AOL radio are good. Also Monkey ball by Sega is very good if you want to test the 3D graphics and motion sensors. I am sure there are going to be many more of such applications in the future. The GOOGLE TALK app is also very good and works just fine on this little genius.

(Email)PUSH/POP/IMAP/CALENDER:Its a much needed and very good upgrade. The Push/Pop and IMAP app works absolutely fine and there is not much hassle synching your outlook and contacts with the iphone. Also you can sync as my accounts you want on your iphone. Also its very easy to sync your outlook calender with your iphone. The changes you make on your iphone are also easily reflected on your PC.

MS Office Documents: Viewing attachments, be it a word doc or a PPT, is really easy so I am sure many enterprise users will be happy with this.

Thumbs Down:

AT&T Network: Though AT&T has rolled out 3G in most of the metropolitan cities, there are many coverage holes still. I am really disappointed with the AT&T coverage. They also charge $10 more just claiming that its 3G. Just hoping that they will upgrade their entire network to 3G (HSPA preferably...or am I asking too much on this one :) ). One suggestion Mr Ralph de la Vega, roll out 3G FEMTOS fast !!!!


VoFi App: There is not a single Voice over Wifi app out there on the store. Actually thts not true, there is Truephone but its paid. I would like something like skype for iPhone. Fring is a good app, but just that its in pre-beta and I do not want to possibly risk damaging my new iphone by installing it yet. But if Apple can get Fring on their store, it would be the best possible thing. But I hear the rumors that AT&T wont allow such a thing as it will harm their revenue stream.

Video Recording: I soo wish Apple provides an upgrade for video recording capability. I will not blame them as they always mentioned they will not provide this functionality in near future.

No Camera Zoom: This is one thing that 2.0MP camera lacks. Though the picture quality is good normally, you cannot zoom and take the picture. There is an application that one can download in order to zoom while wanting to take a snap (not sure if its official on the apple store) but still I thought this should have been already integrated. Little disappointed in this :(

Edit Documents: One cannot edit the MS office documents still, but I hope there are apps that allow you to do so. This mebbe a hassle for enterprise users.

Bugs: There are some bugs in the software when it come to Qwerty keyboard and searching through contact lists. Apple should provide and fix these bugs in their next upgrade.

Overall I think this little Boy Genius is a masterpiece from Apple and now I understand the importance and the hype about Steve Jobs keynote every year.

Femto Cells : Challenges that lie ahead ...

In my previous post , I had explained about the value add that a Femto Cell will bring to an operator as well as the subscriber. Though the Femto Box will be similar to a WiFi router, the complexities involved in making the micro and macro cellular ecosystems to jell-well together, will have to be overcome for the product to become the next big thing in the wireless world (or so it is touted to be).

Listed below are some of the problems I could think of that Femtos face as of today. Vendors in conjunction with the operators will need to an elegant solution that will not only solve the above problems but also lay foundation for next generation Femtos.

Frequency/PN Allocation: Frequency allocation and reuse factor (this is related to 3GPP world, for 3GPP2 world, the same thing will translate to PN allocation ) is something that operators will need to ponder over if the target is for every apartment to have a femto but with no interference issues either between femtos or between femto and the macro world.

Ensuring QoS: Since the femto traffic will be carried over existing broadband, operators will need to ensure that QoS is met. If the ISP's observe net neutrality, then it should not be a problem, but it should not happen that with people downloading a video content through ISP, the Femto voice call is blocked or a delay in the voice call is observed. That will defeat the whole purpose.

Near/Far Interference problem (A Myth ?): From what I have read in articles or through discussions, people wonder whether in CDMA femtos, assuming that the femto and macro are on same frequency, would the near/far problem occur in light of the femto asking the handset to bump up the power resulting in the handset causing interference for the macro users. I personally think that the near/far problem won't exist as the reverse link threshold for a femto will be much less than that of the macro (in order of mWatts).

Soft Capacity: Typically Femtos will support 4-8 users (though the actual number touted by different vendors today is variable but generally in the range mentioned). Now in the event that there are 10-15 people in an apartment, there will be contention (no brain er here).  So it remains to be seen if like macro, the femto soft capacity  would allow that much scalability in the reverse link and if it doesn't then the remaining users shouldn't have issues latching onto the macro.

Supporting Users: How to make sure that only legitimate (by this I mean only those who reside) people latch on to the Femto ? The Femto power would be such that the signal (coverage) would be available outside the apartment too (upto few yards beyond).  In such a case is it possible that a by-stander would latch onto the Femto resulting in a resident's call being blocked ?  

Homogeneous and Independent coverage: It is very important that Femto provides a homogeneous coverage throughout the apartment irrespective of the location. It is possible that for a Femto lying in a basement, its signal would experience a penetration loss. So the forward link budget should be balanced taking all the signal strength losses, fading effects into 

account.

HandOffs: Femtos should be able to support Micro->Macro and Macro->Micro handoffs. This is very important from the subscriber point of view as everyone hates dropped calls (the other devil being blocking probability). I think that as the technologies evolve, Femtos should also support inter-technology handoff (UMTS->LTE, 1xRTT->EVDO->LTE) and Femto->Femto handoff. This all will enhance end user experience.

Business Model: I personally think that for Femtos to succeed, operators have to change their business model. For starters, Operators will have to subsidize the cost of Femto box as much as they can. Sprint started selling their Airrave Femto for $50 where as AT&T is rumored to be selling their Femto for $100 though the cost/Femto to these operators is about $250-$300. Other incentive would be free airtime minutes, flat fee/month etc. The more attractive scheme an operator offers, the more demand will be for their Femtos. Also I think that operators will have to collaborate with ISP's for their backhaul use as mentioned above. 

Albeit all of the above challenges (which I term as Birthing Pains for any new product), the Femto technology looks all set to become the Next Big thing in cellular world and a true platform for much touted and eagerly awaited FMC (Fixed Mobile Convergence).

Femto Cells

I am very fascinated by the latest buzzword in the Telecom Industry, that is "Femtos".

A Femto or a Femto Cell (referred as a Home base station) is a device intended to provide a good cellular coverage inside a home (typically full signal strength). Generally a drop in the network coverage is observed due to the in-building penetration loss. So essentially having a mini-cell tower per say inside the apartment itself will offset the above problem. 

A Femto will typically be an integration of RN, RNC, and PDSN functionality into one box. From operator's standpoint this will mean an additional network element in its network. Large scale deployment of Femtos will indeed lead to the network facing scalability problems.

But I personally think that the Femtos will bring a great value add to an operator, predominantly due to two main reasons:

1) Improved network coverage without the need to have an additional macro cell tower.

2) Improved network capacity as the traffic will be carried over existing broad band connection to the operator's core network, resulting in no additional backhaul costs. 

For subscribers, the value add will be in terms of unlimited usage of voice and data for an incremental cost without using up the valuable airtime minutes. Femtos will essentially turn their Cell Phone into a sole multi-purpose handheld device and also solve network connectivity problems.

WiFi is seen as a potential competitor to Femtos as UMA technology is quite developed and enjoys the first mover advantage but I think that Femtos edge out WiFi due to two main reasons:

1) To use WiFi, the phones need to be WiFi enabled which is not the case today as hybrid phones are costly.

2) The battery life is an issue. 

Recently there has been a lot of traction in the industry about the FemtoCells as seen in Mobile World Congress as well as in CTIA. Sprint has already rolled out its Femto service in Airrave, also AT&T apparently has signed $500m deal with ip access to roll out the FemtoCells in its network and Vodafone has also issued RFP's for Femtos. Femto vendor Airvana has also signed a global OEM deal with Motorola for its Femto solution. 

As Nothing is perfect, Femtos also face several problems which the operators and vendors will have to overcome to make this product a success in the market. I would reckon that 2009 is going to be the year of Femtos. 

For completeness, in my next post I will highlight the problems that Femtos face....