Simple and Effective Messaging and more:Whatsapp

Few months ago , I downloaded this application to my Android OS phone. Actualy it is very user friendly and I realy satisfied with this application.

 

Whatsapp is very popular real time messaging software for smart phones. We can say that It is simply sort of SMS+MMS+ File Sharing and uses GSM and/or Wi-Fi.

 





Whatsapp Chat Window



It is very easy to attach some file(s) during chatting. You can specify group and chat with your friends all together. Plus, you can add emotions.

 

Deleting message history and even changing background of chat screen is nice things. Also it has "last seen". it is very noteful to control your friends they were online or not :)

Another good thing is you do not annoy with boring adds during chating.

 

Application uses your phone contacts. So you do not need to add by putting  him/her email  etc account to app.

 

In my opinion, simplicity is just coming for that reason.

Total download number is between 100milion -500 milion. So it is fantastic huge number.

On the other hand, please be aware this application is not free. Ok. it seems it is free for first dowloading from Google Play Store but you need to check account settings. It is just trial version. You have to pay and there is 3 payment options for 1 -3 or 5 years.

Anyway, I put following picture which explains how to check your paying settings. Please just follow settings --> Account --> Paying Info --> Validity

Checking validity date of application

Overall, this is very cute application. Unfortunately, I heard some security vulnerabilities if you put your SIM to another phone. http://www.neowin.net/ explains this case in more detail.

 

Read More

Are Base Transceiver Station and Mobile Healthy?

This is very common issue for many people and actualy. So we decided to explain this topic in scientific way.
RF is non -ionizing radiation category like Microwaves, Infrared etc. On the other hand,  ultraviolet, X-Rays, Gamma Rays are in ionizing radiotion category.

GSM Standards are defined by ETSI (European Telecommunication Standardization Institute) in Europe and FCC (Federal Communication Commission) in USA. Since RF is non-ionising radiation;
ICNIRP (International Commission on Non-Ionizing Radiation Protection ) rules are means a lot to us. WHO (World Health Organization) and ILO (International Labor Organization) recognizes the ICNIRP studies. Europe Countries take ICNIRP radiation limits about human health. In USA, FCC takes care the IEEE (Institute ofElectrical and Electronics Engineers) And ANSI (American National Standarts Institute) studies.

So , for GSM users like us, following values are important for us;

What is the meaning of above values?
Above things are just hazard limits  of RF and it is based on 0.1 celcius increasing human body heath.
On the other hand, In Turkey, above limits are more safety than Europe Countries.

As a result,

Output power of mobile phones dynamically changes according to distance between antenna tower etc. Average power is  1W, maximum 2W (it is up to GSM frequency too) and  Output power of BTS antenna is maximum 60W.  These values are not enought to heat water actually. This is good for us.
Also There is no clear evidence between cancer and GSM equipments. But it does not indicate that everything is green. Authorities are still searching the relationship between  Radio Frequncy and Human Health.
And please do not forget, somethings which seems innocent for people generally but it is more dangerous than GSM Freq. like High Voltage Lines.

We can just do following for better protection:

1. Do not make a call in your call without using any special kit. As, only one proof about hazard of GSM is, talking with mobile phone while driving, increases traffic accident risk :)
2. Do not make long calls or use headset etc
3. Try to keep distance your body and mobile
4. Distance between antenna and human might be at least ~9 meters.

By the way, We strongly reccomend following links for further information:


http://www.who.int/peh-emf/publications/en/mcmcradiationmobilephonebk.pdf

http://www.samsung.com/sar/sarMain?site_cd=&prd_mdl_name=GT-N7100&selNatCd=US&languageCode=EN

http://www.fcc.gov/encyclopedia/specific-absorption-rate-sar-cellular-telephones
Turkish Web Site:
http://www.biltek.tubitak.gov.tr/sandik/gsm.pdf
And very good  unit conversion site:
http://www.compeng.com.au/emc_conversion_tables_rf_calculator.aspx

Read More

LTE Voice Codec AAC-ELD

We are using mp3 file format generally in our computers and mobile phones to be able to listen music.  In reality, we are not listening original sound there.  Original sound is sort of raw data and we are just hearing compressed version of original sound.

 Raw Voice
Raw voice for example 16 bit 44 kHz wave format (.wav) 3 minutes will be approximately 30 megabytes. This is very huge size. If it is compressed into 128Kbps mp3 then it is around 3 megabytes. Simply, we can see that file size significantly decreases if we use codec.

 

 

What is Codec?

Codec is a short name for coder-decoder the software that takes a raw data file and turns it into a compressed file. An audio codec is a device or computer program capable of coding or decoding a digital data stream of audio.  Because of original sound size is big, we need to use codec for many perspectives like network stability etc.

GSM Codecs.

In GSM history, many codec types  have been developed.  These are;

Half Rate (HF)

Full Rate (FR)

Enhanced Full Rate (EFR)

 EFR introduced in 1997

Adaptive Multi Rate – Narrow Band (AMR or AMR-NB)

This is using in GSM and UMTS, introduced in end of 1990s.

Adaptive Multi Rate – Wide Band (AMR-WB)

Improved version of AMR due to a wider speech bandwidth compared to AMR Narrowband. It is commercially released in 2008. Also this is introduction with HD-Voice quality.

Advanced Audio Coding – Enhanced Low Delay

This is final developed codec for GSM World and using in LTE networks. This codec is designed for  Full-HD Voice. To be able to reach full HD voice quality,  codec  has to support  ~20khz frequency.  To compare differency; previously explained  HD-Voice branded codec  AMR-WB   supports only 7kHz.By the way, very important point is, both network and handsets have to support this feature.
 

<iframe width="560" height="315" src="http://www.youtube.com/embed/sdpGRpIwO9k" frameborder="0" allowfullscreen></iframe>

 

Read More

Decibel and dBm in our GSM world

If you are familiar with gain issues, link budget, antenna installation and even signal-to-noise ratio calculations etc., sometimes abbreviations regarding decibel might cause little troubles and we might be confused to understand differences between these. That’s why I decided to prepare quick tips to help people.

Decibel of voice demostration

 

First, what is decibel? It is just simple logarithmic unit of input and output power ratio. A decibel is one-tenth of a Bel - named after Alexander Graham Bell, the inventor of telephone. As a simple demonstration;

Decibel = 10 log (P / Pref)
*P= signal power and Pref = reference power

Ok, why it is logarithmic? What is the benefit of it?

One of the answers is it is magic of logarithm so that we do not lost in quantity. Ratio is more meaningful and easy to make calculations in real world. Otherwise you might need to use very big amount of numbers.

dB is not just dB? It has some friends like dBm, dbi?

Let’s talk about dBm then. dBm is power in dB relative to 1 mW.

Thanks to Wikipedia, following formula is very useful to help you:

 

0 dBm equals 1 milliwatt. A 3 dB increase represents roughly doubling the power, which means that 3 dBm equals roughly 2 mW. For a 3 dB decrease, the power is reduced by about one half, making −3 dBm equal to about 0.5 milliwatt or 500 microwatts.

Note: dB(isotropic) – the forward gain of an antenna compared with the hypothetical isotropic antenna, which uniformly distributes energy in all directions. Linear polarization of the EM field is assumed unless noted otherwise.

Ok, lets imagine, you are talking with a friend via mobile phone. There should be value range of signal strength level in order to keep your call. Our GSM authorities say that; we can hear our friend’s voice if this level stays between from -110 dBm to -48 dBm.

Decibel Imagination :)

But do not forget, -110dBm is final edge for your call. If you get close to this value you would feel the decreasing voice quality.

As practically;

-110 to -100 = Call Drop and/or Bad Quality
-99   to -90   = Getting bad/signal may break up
-89   to -80   = it is ok  but maybe
-79 to -65 = Good
Over -65 = Excellent

Why these values are negative?

Since our reference is 1milliwatt, this (-) value indicates that signal power is less than 1mw.
As an example from Wikipedia again:

-80 dBm = 10pW  

Typical range (−70 to −90 dBm) of wireless received signal power over a network (802.11 variants)

80 dBm = 100kW 

Typical transmission power of FM radio station with 50-kilometre (31 mi) range

I hope this short quick tip type blog is useful in your life.

 Pictures:

createheart.com 
http://onlyhdwallpapers.com/
www.msefayilmaz.com/

  

Read More

What is changed after introducing with microSIM?

 Hello everybody, after a half month, finally our new blog pops up. Because of a lot of stuff to handle, I could not be here. Anyway, I decided to write something about SIM cards. Like I said from prior blogs our goal is share information with people with simply and useful practically so we will not go into detail and get your feedback with questions, suggestions.  So that, we can enhance our knowledge.

What is SIM?

SIM means Subscriber Identity Module. SIM card is smart card, it holds subscriber information like IMSI, MSISDN ,SMS server information and memory for contact info , sms . SIM card also keeps authentication parameters like Sres, Op/Opc, Ki etc .

The European Telecommunications Standards Institute (ETSI), which sets the standards for SIM cards, tells us that except for the size of the plastic around the chip, micro SIM cards are identical to the SIM cards we normally find in phones.

There are two type SIM cards;
The first basic families are SIM/USIM (for 2G and some 3G networks), the RUIMs (for CDMA networks) and UICCs (for 3G and LTE networks).

USIM:Universal SIM   RUIM: Removable User Identity Module  UICC: Universal Integrated Circuit Card

Why do I need to use SIM card?

SIM card is our ID in mobile phone network. To be able to get into this network we need authentication. So this very small smart card holds all authentication parameters. Regarding GSM technology it uses different type Authentication algorithms like Milenage in UMTS and Snow-3G in LTE.

SIM Card capacity:

Each product family is then defined by the size of the memory made available to the telecom operator. They are usually 64KB, 128KB, 256KB, 500KB, 700KB, etc.  But i did not see any SIM card in real World with capacity 700kb for gsm.

 Which phones are using microSim?

Lates phones are Samsung Galaxy S4, BlackBerry Q10, LG Optimus G LTE 4G, HTC One 4G, Sony Xperia Z, Motorola RAZR i and Nokia Lumia 520.

Why microsim?
I could not find a good answer for it because of vendor requests. Physical Size of chip in both SIM and MicroSim are same.  Maybe it is for preventing unlocking but it is cutting to new microSIM shape with some special tools. So this theory is not valid at least in Turkey. If someone knows the actual reason please enlighten me J

How can I program SIM card

First you have to find SIM card reader. Some of them are Orga and Gemalto. But do not forget you cannot find any tool that can reach the files where authentication parameters are storing.

 Does SIM have special applications on it?

We call it VAS; it stands for Value Added Services. A value-added service (VAS) is a telecommunications industry term for non-core services or, in short, all services beyond standard voice calls. It was SMS, MMS and such kind of basic things in the past. After changing customer expectations it is changed to more advanced applications like Push-To-Talk, Call conferencing, SMS auto reply, Weather information, voicemail and so on. Since VAS is not simple thing, I am planning to explain VAS in future.

 

Sources:

http://www.eservglobal.com/solutions/value-added-services

http://cellplan4u.com/store/product_info.php?products_id=41

http://apcmag.com/card-tricks-why-apple-put-a-microsim-into-the-ipad.htm

http://asia.cnet.com/whats-the-big-deal-about-the-microsim-62200148.htm

 

 

Read More

User Speed Rates of GSM Technologies

Tremendous achievements of wireless world is providing more enjoyable lifestyle to us. Especially,  watching HD movies via stream is edge corner now for end users like me.

Mobile trend is growing rapidly. Following figure shows the interesting statical result from JohnHughes blog.

 Think about it, you are living with your search tool just in your pocket. You do not need to use any cable,device connection etc and you can reach internet very easly with sufficient speed generally. 

Because of the importance of smart phones, we are facing with enhancing wireless mobile telecommunication technologies day by day.

We are planning to explain actual speed rates of each technologies by starting with GPRS technologies briefly.
 

 2G technologies could not reach the Mbps speed rates unfortunately except EGPRS-2. EDGE has 237 kpbs DL speed theoretically. it varies between 120Kbps to 384Kbps practically for per user. Other name of EDGE is 2.75G.

With the introducing WCDMA, we have met superior speed rates. above picture demonstrates the performances of 3G and 4G techs.

Thi biggest issue for high speed wireless networks is the lack of bandwidth. We can say it also as range of usable frequencies. So we put following pictures from speedtest.net to compare pratical and theoretical results for user speed rates.

4G VERIZON USA
  

4G AVUSTRALIA

 4G TMO  EURO

Note: I checked the users fro this test and one user speed rate was 980.92 Mb/s within 188 total tests . I subtracted that one and recalculated the speed test and it was ~10Mbps like in Verizon USA.
 
Speed of Wireless techs has a lot of obstacles like total user, location and velocity, many type of interferences, total users  etc. But we can say , humanity has got very good achievements  about it during this decade and we can easily say that 4G is really great even though it can not be able to reach to wireline speeds at least these years.
 

REFERENCES
http://www.gsma.com/ 
http://autoblog.johnhughes.com.au 
http://www.speedguide.net/faq_in_q.php?qid=366 
http://www.radio-electronics.com/ 
http://www.speedtest.net
http://www.wisegeek.com/what-is-evdo.htm 
http://www.zdnet.com 

Read More

LTE Security

Based mobile networks supporting a rapidly growing number of computationally powerful devices  such as  smartphones and tablets is changing the mobile security landscape and will fundamentally 
change the way we perceive and deal with mobile security. Mobile networks are becoming more

pervasive, more widely used, and more deeply connected to other network.

 

Devices and the core network are most heavily targeted parts of the mobile network.



Basicaly we can separate the security as for subscriber authentication and attacking to mobile to core devices.

Authentication procedures use very complex algorithms, personally it is not a big threat for mobile operators. By the way, we are starting with authentication very briefly

Authentication
   
Operators like Verizon in USA are using 3GPP  SNOW 3G Specification for Confidentiality and Integrity Algorithms UEA2 & UIA2, 128-EEA1 & 128-EIA1.
  
SIM means Subscriber Identity Module (SIM). All wireless mobile technologies have different type of SIM cards. For example,USIM is using in 3G Sim cards with Milenage Authentication. Before 3G, we were using A3 and A8 authentication algorithms. 

A3/A8 had some weakness, that enable attackers to break the encryption key in less than one second, breaching customer’s identity and allowing billing fraud and  putting telecom operators in a serious legal situation.

The older SIM cards are not compatible and may not be used in LTE.

Security the keys used are128 bits in LTE.

  
Important: Mobile Phone has to support SNOW 3G algorithm.

 Securing LTE Backhaul

 

Most attacks will be directed at the mobile core network, external sites, and subscriber data and devices, but they can also be more limited in scope and target a single eNB or a group of nearby eNBs (eNB identity spoofing and impersonation).Tampering, traffic hijacking, eavesdropping, DoS,compromised control data,unauthorized access,and loss of accountability of the control plane are the biggest threats to the core network.

To secure traffic,as an my personal opinions based on my researches an IPsec tunnel has to be established between the eNB,and the MME, SGW and O&M in the core network over the user,control and management plane, and terminated at a SEG (security gateways) that sits at the border of the trusted area.

REFERENCES
http://www.mcit.gov.sa/nr/rdonlyres/d762830c-fbe7-4b36-aafc-780cfbafc92c/0/paper36.pdf 
http://www.3gpp.org/ftp/Information/presentations/presentations_2011/2011_05_Bangalore/DZBangalore290511.pdf
http://support.verizonwireless.com/faqs/VZAccess/4g_sim_card.html
http://security.stackexchange.com/questions/21395/how-is-4g-lte-encrypted
http://www.etsi.org/index.php/services/security-algorithms/3gpp-algorithms
http://www.authentec.com/Products/EmbeddedSecurity/SemiconductorIP/3G4GLTECiphers.aspx
http://itmf.uga.edu/minutes/2011-03-03/verizon_presentation.pdf
http://www.embedded.com/electronics-products/electronic-product-reviews/ip-eda-products/4212398/Elliptic-launches-security-processing-engine-for-4G-wireless-markets
http://www.radio-electronics.com/info/cellulartelecomms/lte-long-term-evolution/lte-security-authentication.php
http://www.sciencedirect.com/science/article/pii/S0140366410003105
http://www.slideshare.net/aliirfan04/lte-security-overview
http://www.f5.com/pdf/white-papers/wireless-security-lte-networks-wp.pdf
http://internetandwebsecurity.blogspot.com/2010/10/radisys-introduces-carrier-grade-lte.html
http://www.tellabs.com/resources/papers/tlab_ipsec_wp.pdf

Read More