2011 - Telecommunications Blog

A blog for mobile communications systems GSM , UMTS and LTE

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Monday, December 26, 2011

INTRODUCTION TO RF PLANNING 1

12/26/2011 10:19:00 AM 1
INTRODUCTION TO RF  PLANNING 1
• Designing a cellular system - particularly one that incorporates both  Macrocellular  and Microcellular  networks  is  a delicate  balancing  exercise.

• The goal  is  to  achieve  optimum  use  of  resources and maximum revenue potential whilst maintaining a high level of system quality.

• Full consideration must also be given to cost and spectrum allocation limitations.

• A properly  planned system  should allow  capacity  to  be added economically when traffic demand increases.

• As every urban environment is different, so is every macrocell and microcell network. Hence informed and accurate planning is essential in order to ensure that the system will provide both the increased capacity and  the  improvement  in network  quality where  required,
especially when deploying Microcellular systems.


• RF planning plays a critical role in the Cellular design process.

• By doing a proper RF Planning by keeping the future growth plan in mind we can reduce a lot of problems that we may encounter in the future and also reduce substantially the cost of optimization.

• On the other hand a poorly planned network not only leads to many Network problems , it also increases the optimization costs and still may not ensure the desired quality.

Tuesday, September 13, 2011

Introduction to Antenna

9/13/2011 06:34:00 PM 0
Introduction to Antenna
  • An antenna is an electrical conductor or system of conductors
             * Transmission - radiates electromagnetic energy into space
             * Reception - collects electromagnetic energy from space
  • In two-way communication, the same antenna can be used for transmission and reception


Antenna Definition

   An  antenna  is  a  circuit  element that  provides  a  transition  form  a guided wave on a transmission line to  a  free  space  wave  and  it provides  for  the  collection  of electromagnetic energy.

  In  transmit  systems  the  RF  signal  is generated,  amplified,  modulated  and applied to the antenna.

   In receive systems the antenna collects electromagnetic  waves  that  are “cutting”  through the  antenna  and induce  alternating  currents  that  are used by the receiver.

Polarization


   Polarization  is  the  direction  of  the  electric field and is the same as the physical attitude of the antenna.
 
          - A  vertical  antenna  will  transmit  a  vertically polarized wave.

  The  receive  and  transmit  antennas  need  to possess the same polarization.

Monday, July 18, 2011

WCDMA Network Planning 3

7/18/2011 05:22:00 PM 0
WCDMA Network Planning 3
Conditions for planning


** Conditions :

• capacity not constant.
• separate analysis for UL/DL.
• joint coverage/capacity analysis.
• HO areas and levels affect directly system capacity.
• basic shared resource is power.

** Objective parameters :


• coverage.
• capacity (blocking).
• good link quality (BER, FER).
• throughput delay, for packet services Methods.
• preplanned during network planning process.
• real time radio resource management.
• real time power control.





Network planning



Resource reservation for handling expected traffic without congestion.
           – load per cell/sector, handover areas.

Sets allowable “power budget” available for services.
           – load higher than expected.
           – load “badly” distributed.
           – implements statistical multiplexing.

Estimates average power/load, variations of it are taken care in run time by RRM.
           – maximal allowed load versus average load.

Thursday, July 7, 2011

WCDMA Network Planning 2

7/07/2011 02:19:00 AM 0
WCDMA Network Planning 2
Planning methods

•  Preparation phase.
           – Defining coverage and capacity objectives.
           – Selection of network planning strategies.
           – Initial design and operation parameters.

Initial dimensioning.
           – First and most rapid evaluation of the network elements count and capacity of these elements.
           – Offered traffic estimation.
           – Joint capacity coverage estimation.

Detailed planning.
           – Detailed coverage capacity estimation.
           – Iterative coverage analysis.
           – Planning for codes and powers.

Optimisation.
           – Setting the parameters.

Soft handover.

Power control.

Verification of the static simulator with the dynamic simulator.
           – Test of the static simulator with simulator where the users actual movements are modelled.

Sunday, June 19, 2011

3G Security Principles 1

6/19/2011 11:32:00 AM 0
3G Security Principles 1
  It was agreed that any new security architecture must be based on an evolution of GSM and must adopt four basic principles:
  •   It will take into account the additional features needed for actual or predicted change in the operating environment
  •   It will maintain compatibility with GSM wherever possible
  •   It will retain those features of GSM that have proved to be robust and useful to the user and network operator
  •   It will add or enhance features to overcome actual or perceived weaknesses in 2G system
1-  Additional features :

  One of the main reasons for the development of the 3G system to make higher value services available to as many users as possible world wide, using a universal design of the handset. However, this increases the number of relationships, as the number of Users, Service Providers, and Network Operators in the market expands.

  This increased level of service interaction increases the number of potential attackers and the opportunities open to them. This was not too much of a problem in the initial roll out of GSM, as there were a relatively small number of operators and the risk of compromise was low.

  For 3G, the networks are getting smaller and more numerous, so opportunities for hackers and other abusers of networks will increase. Even if deliberate abuse is not considered likely, unintentional mishaps may occur as a result of the complexity and the rate of new service introduction.

Saturday, May 21, 2011

WCDMA Network Planning 1

5/21/2011 12:47:00 AM 2
WCDMA Network Planning 1
Planning

     • Planning should meet current standards and demands and also comply with future requirements.
     • Uncertainty of future traffic growth and service needs.
     • High bit rate services require knowledge of coverage and capacity enhancements methods.
     • Real constraints
               – Coexistence and co-operation of 2G and 3G for old operators.
               – Environmental constraints for new operators.
     • Network planning depends not only on the coverage but also on load.

Objectives of Radio network planning

     • Capacity:
               – To support the subscriber traffic with sufficiently low blocking and delay.
     • Coverage:
               – To obtain the ability of the network ensure the availability of the service in the entire service area.
     • Quality:
               – Linking the capacity and the coverage and still provide the required QoS.
     • Costs:
               – To enable an economical network implementation when the service is established and a controlled network expansion during the life cycle of the network.

Thursday, May 5, 2011

MAC Layer in WiMAX IEEE 802.16

5/05/2011 04:11:00 PM 0
MAC Layer in WiMAX IEEE 802.16
  The MAC layer of IEEE 802.16 is designed to serve sparsely distributed stations with high data rates, where the SSs are not required to listen to the other stations like the MAC in IEEE 802.11. 

  The BS schedules the transmissions of the corresponding SSs in advance. The MAC of WiMAX is reservation-based and contention-free. The SSs need to contend only when they access the channel for the first time at the connection admission control stage. 

  The reservation-based resource allocation allows the WiMAX BS to serve a large number of SSs as well as the guarantee of QoS in the connection level for both uplink and downlink traffic. 

  Compared with 802.16, Wireless Local Area Networks (WLAN) based on IEEE 802.11 terminals usually have intermittent  traffic that contends every time before transmitting, where the efficiency is significantly impaired when more stations enter the network.


  The main purpose of the MAC protocol is the sharing of radio channel resources among
multiple accesses of different users. The MAC also contains a separate security sublayer handling authentication, secure key exchange, and encryption.

Tuesday, May 3, 2011

WiMAX IEEE 802.16 family

5/03/2011 08:08:00 PM 0
WiMAX IEEE 802.16 family
WiMAX IEEE 802.16 family :.
  •  IEEE 802.16a: The standard specifies the operation from 2GHz to 11GHz, both licensed and license exempts. Because the signals at lower frequency can penetrate barriers and thus a line-of-sight connection between the transceiver and receiver is not required, most commercial interests have focused mainly on the lower frequency ranges. Under this premise, IEEE 802.16a standard was thus completed in January 2001. It enables the WiMAX implementations with better flexibility while maintaining the data rate and transmission range. IEEE 802.16a also supports mesh deployment, which can extend the network coverage and increase the overall throughput.

  •  IEEE 802.16b:  This extension increases the spectrum to the 5 and  6 GHz frequency bands, which provides QoS guarantee to ensure priority transmission for real-time applications and to differentiate service classes for different traffic types.

  •  IEEE 802.16c: As the Work Group’s initial interest, IEEE 802.16c defines a 10 to 66 GHz system profile that standardizes more details of the technology. These high frequency bands have more available bandwidth, but the signals cannot diffract the obstacles and require line of sight deployment. 

  •  IEEE 802.16d:  Approved in June 2004, IEEE 802.16d upgrades the 802.16a
standard. This extension aims to improve performance for 802.16 especially in the
uplink traffic.

  •  IEEE 802.16e:  This technology standardizes networking between fixed base stations (BSs) and mobile base stations (MSs), rather than just between base stations and fixed recipients. IEEE 802.16e enables the high-speed signal handoffs necessary for communications with users moving in vehicles. It promises to support mobility up to speeds of 70-80mi/h. The subscriber stations (SSs) could be personal communication devices such  as mobile phones and laptops.

We will continue the family next posts .

Wireless Ad hoc Networks

5/03/2011 10:59:00 AM 1
Wireless Ad hoc Networks
  Wireless ad hoc networks have special characteristics related to node mobility, node self-configuration and the lack of centralized access points (APs). However, wireless ad hoc technologies have several disadvantages when compared to traditional wireless
networks, including their limited resources, such as:

       ** Lower processing capacity
       ** Limited memory
       ** Battery dependency

  Because operations are not centralized in a single access point, information is openly distributed among the network nodes. As a result, wireless ad hoc networks are not as secure as typical wireless networks.

  Wireless ad hoc networks are usually associated with wireless mesh networks; however, these two concepts can be dealt separately.

  The essential idea of wireless ad hoc networks is that they are mobile and dynamic. This
concept is not at all new.
Source : IEEE

Monday, April 25, 2011

LTE vs WiMAX : 4G Comparison

4/25/2011 03:54:00 AM 0
LTE vs WiMAX : 4G Comparison
  Both are 4G technologies designed to move data rather than voice. Both are IP networks based on OFDM (Orthogonal Frequency Division Multiplexing) technology.

   WiMax is based on a IEEE standard (802.16),Depending on the spectrum alloted for WiMax deployments and how the network is configured, this can mean a WiMax network is cheaper to build.

     WiMAX offers peak wireless data speeds of up to 60 Mbps on the downstream and 25 Mbps for sending data upstream.

    Long Term Evolution (LTE), can ferry data to you at download speeds of 100 Mbps and support upload speeds of 50 Mbps.

    That means you can download about two 5-minute MP3 files every second. Think about that. Sure, it would only take WiMAX about seven minutes to download a single 5-minute MP3 file, which is still fast, but it’s nowhere near the theoretical scale of LTE.


LTE World summit 2011, 17-18 May 2011 at Amsterdam RAI

4/25/2011 01:11:00 AM 0
LTE World summit 2011, 17-18 May 2011 at Amsterdam RAI
7th LTE World summit is schedule on 17-18 May 2011 at Amsterdam RAI.




Features of this event will be :

Now in its 7th Year! This is THE LTE event of the year!
  • 2500+ Attendees from 100+ countries
  • 150+ High-level speakers
  • 120+ Exhibitors, meeting rooms & hospitality suites
  • 100+ Operator Case Studies
  • 50%+ Director-level and above attendance - meet the decision makers here!

Thursday, April 21, 2011

4G LTE: MIMO and MRC

4/21/2011 04:44:00 AM 0
4G LTE: MIMO and MRC
MIMO and MRC:-

    o LTE system uses MIMO (multiple input multiple output) as advanced multiple antenna technique in order to achieve the ambitious requirements for throughput and spectral efficiency.
    o maximal ratio combining (MRC) : is used to enhance link reliability in challenging propagating conditions when signal strength is  low and multipath conditions are challenging. 
 

 Downlink MIMO:-

    o a 2x2 configuration for MIMO i.e. 2 transmit antennas at the base station and 2 receive antennas at the terminal side. 

Sunday, April 17, 2011

Intel Is Said to Design Phone for ZTE in China Market for Sale

4/17/2011 08:38:00 PM 0
Intel Is Said to Design Phone for ZTE in China Market  for Sale
   Intel may be attempting to secure a spot for their mobile chips by first infiltrating the Chinese phone market. Their sources claim that Intel has submitted designs of a handset based on a version of Intel’s Atom microprocessor. The phone will be manufactured by ZTE Corp and may go on sale in China. 

   
     Intel is trying to offer its processors for the smartphone manufacture but till now we haven’t seen any gadget with Intel processor. It is fact that Intel processors are very commonly available

Saturday, April 16, 2011

SC-FDMA (Single Carrier Freq Domain Multiple Access)

4/16/2011 04:47:00 AM 2
SC-FDMA (Single Carrier Freq Domain Multiple Access)
SC-FDMA (Single Carrier Freq Domain Multiple Access) used in Up-Link in LTE.

    o The system uses SC-FDMA as uplink multiple access method instead OFDMA to decrease the PAPR and power requirements.

    o It offers the same degree of multipath mitigation but because the transmission is
on single carrier PAPR is lower.


     o The basic idea is to add cyclic prefix to the mapped symbols and in the receiver
multipath distortion can be handled by the same method as OFDM (carrier based equalization).

Thursday, April 14, 2011

JAJAH Facebook Calls for iPhone Beta released !

4/14/2011 11:18:00 PM 0
JAJAH Facebook Calls for iPhone Beta released !
   Following Tuesday’s release of the JAJAH App for Android, JAJAH Facebook Calls for iPhone beta released for iPhone Free Calls From iPhones to Any Facebook Friend. It's available in the US and Canada now.

To make a Facebook Call:

  • Download the JAJAH App for iPhone from iTunes
  • Connect to Facebook
  • Select a friend from the “online friends” list
  • They will receive a message within Facebook chat advising of the call. Once they accept,

TELUS to launch 4G LTE in Canada in 1st H 2012

4/14/2011 06:58:00 PM 1
TELUS to launch 4G LTE in Canada in 1st H 2012
   LTE technology supports manufacturer’s rated peak download speeds of up to 150 megabits per second (Mbps) and upload speeds of up to 70 Mbps.

   Canadian operator TELUS has announced the plan to launch of LTE network 1st H 2012. Following field testing in 2011 and the completion of an RFP process currently underway, construction on TELUS' LTE network will begin in the latter half of 2011 in major urban markets across Canada. 

   Telus – the country’s third-largest operator – said that construction of the new network will begin in the latter half of 2011 in “major urban markets” across Canada. It will initially operate on

Wednesday, April 13, 2011

Alcatel-Lucent and nTelos Wireless complete LTE field trial

4/13/2011 03:52:00 PM 0
Alcatel-Lucent and nTelos Wireless complete LTE field trial
   Virginia-based nTelos Wireless and Alcatel-Lucent have accomplished an end-to-end Long Term Evolution (LTE) field trial in Waynesboro, Va.

   “This trial enables us to make informed decisions on how to smoothly evolve our network and incorporate 4G LTE into the existing infrastructure, particularly in terms of end-user performance, throughput, latency and Quality of Experience,” said Bobby McAvoy, Senior Vice President, Wireless Engineering & Operations for nTelos Wireless.

   For this trial, Alcatel-Lucent provided an end-to-end integrated solution including 4G LTE base

Infrax Systems (IFXY) Announces the Availability of New 1.4-1.6 GHz Upgradeable WiMAX / LTE Base Station for Rural Broadband Networks

4/13/2011 03:37:00 PM 0
Infrax Systems (IFXY) Announces the Availability of New 1.4-1.6 GHz Upgradeable WiMAX / LTE Base Station for Rural Broadband Networks
    Infrax Systems, Inc. (OTCBB: IFXY), a global provider of unified Smart Grid-related products and services for the Energy and Utility industries, today announced the availability of a new upgradeable WiMAX/LTE base station. This new base station option allows network operators and service providers to utilize the desirable 1.4-1.6 GHz frequencies. The addition of these new base stations will provide operators of rural broadband networks better range than the typical 2.5 or 3.5 GHz WiMAX. These new base stations also have the capability of being upgraded from WiMAX (802.16e) to Long Term Evolution (LTE) via firmware. These modular 4G base stations can even provide the ability to change to a different frequency by changing radio modules to provide more longevity of the platform and protect network operator's investments.

   The American Reinvestment and Recovery Act appropriated $7.2 billion for the Department of Agriculture’s Rural Utilities Service (RUS) and the Department of Commerce’s National

Ericsson to support China Mobile's TD-LTE Trial Network in the City of Shenzhen

4/13/2011 03:23:00 PM 0
Ericsson to support China Mobile's TD-LTE Trial Network in the City of Shenzhen
   China Mobile has selected Ericsson to participate in the world’s largest TD-LTE trial network deployment to date. With the approval of the Chinese Ministry of Industry and Information Technology (MIIT), Ericsson will build trial network in the city of Shenzhen.

   The approval by MIIT follows the successful completion of interoperability tests of Ericsson's TD-LTE network equipment with multiple chipset manufacturers. As part of its efforts to further develop the global ecosystem, Ericsson is proactively conducting interoperability tests with leading international players such as ST-Ericsson and Qualcomm.

  "China Mobile has always been a formidable force in driving the evolution of telecommunications technologies. As a longtime strategic partner to China Mobile, Ericsson will fully support our customer in its tremendous endeavor to make TD-LTE a reality in the

Epitiro tests TeliaSonera's LTE network performance

4/13/2011 03:07:00 PM 0
Epitiro tests TeliaSonera's LTE network performance
   Epitiro has completed the independent speed, latency and voice quality-of-experience analysis on a commercially available LTE network. Tests recorded peak broadband download speeds of 48Mbps (36.1Mbps mean) where as Mean latency was just 23ms.

  Epitiro, at the same time, tested TeliaSonera's legacy 3G network; LTE delivered mean download speeds nine times faster, and its latency was five times faster. Analysis of IP calls to the UK, made using voice over LTE (VoLTE), found the quality to be ‘excellent’ on average with only 1 call in 298 being of inferior quality.

  “Based on our observations, this LTE rollout is directly comparable to high-speed fixed

Monday, April 11, 2011

4G LTE structure

4/11/2011 03:18:00 PM 0
4G LTE structure
LTE PHY layer block diagram:-

We can implement LTE Physical layer Block diagram in Matlab .



Frame structure: it is FDD frame which is 10ms divided into 10 subframes each
of 1ms & each subframe is divided into 2 slots of 0.5 ms which carry 6 or 7 OFDM
symbol.

Sunday, April 10, 2011

4G LTE Key Features ( EPS to EPC)

4/10/2011 03:09:00 PM 0
4G LTE Key Features ( EPS to EPC)
EPS to EPC

   A key feature of the EPS is the separation of the network entity that performs control-plane functionality (MME) from the network entity that performs bearer-plane functionality (SGW) with a well defined open interface between them (S11).


LTE S11: -

    An IP interface between MME and SGW! GTPv2 is the protocols used at the application

4G LTE Physical layer overview

4/10/2011 02:22:00 PM 0
4G LTE Physical layer overview
What is LTE?

    3GPP LTE (Long Term Evolution) is the name given to a project that aims to improve the
UMTS mobile phone and it is not a standard but it will result in the release 8 of UMTS
and it can be considered the real 3.9G & invited to join the 4G family.

Technical specifications:-


LTE PHY layer block diagram:-

Thursday, April 7, 2011

Call Number Identification in GSM

4/07/2011 12:40:00 PM 1
Call Number Identification in GSM
    If an adversary knows certain information (IMSI, IMEI, MSISDN) about the subscriber or a mobile phone, he can then identify individual phone calls, although this does require extensive technical effort.

    With the aid of IMEI it is possible to selectively filter calls out from the datastream on the mobile network radio relay links. Calls can also be identified in the public telephone landline network, for which knowledge of the subscriber call number is necessary. With the appropriate interception equipment, the IMSI and IMEI can be ascertained directly on the radio link between mobile phone and base station.

Authentication in GSM

4/07/2011 12:35:00 PM 0
Authentication in GSM
     The SIM card can be protected against unauthorised access with a four- to eight-digit Personal Identification Number ( PIN). After switching on the mobile phone, the subscriber identifies himself to the card by entering this PIN. If an unauthorised person gains possession of a SIM card, he cannot use it without also knowing the PIN. To prevent improper use of the SIM card, the PIN should therefore be kept in safe place.

      The subscriber identifies himself to the network provider on registering by means of the SIM card and the cryptographic algorithms held on it. Authentication is effected with the aid of an authentication key which is known only to the network provider in the AUC and the subscriber on the SIM card.

     Normally the data is only transmitted encrypted on the radio link between the mobile phone and the base station. Encryption is not used on any of the other transmission paths, either in the

Tuesday, April 5, 2011

Samsung Galaxy Tab 10.1 3G info.

4/05/2011 07:37:00 PM 0
Samsung Galaxy Tab 10.1 3G info.
   Samsung Galaxy Tab 10.1 3G tablet with no GSM voice communication capabilities.
   It supports GSM 850 / 900 / 1800 / 1900 & HSDPA 850 / 900 / 1900 / 2100 and Wi-Fi 802.11 a/b/g/n, Wi-Fi hotspot .It has been Announced in March 2011 .

   It will be release in June 2011.Its dimensions are 256.6 x 172.9 x 8.6 mm .Its weight is 595 g
The display type is TFT capacitive touchscreen, 16M colors and support :

Verizon iPhone 4 equally satisified

4/05/2011 05:02:00 PM 0
Verizon iPhone 4 equally satisified
     AT&T and Verizon iPhone 4 owners are more than twice as likely to report dropped calls than Verizon customers, says survey .

    Taken from a group of 4,068 people, the survey's results show 82 percent of Verizon subscribers being "very satisfied" versus 80 percent for AT&T. Those results are similar to an industry-wide, non-iPhone-specific poll conducted separately by ChangeWave. In that poll, 4.6 percent of AT&T subscribers reported dropped calls, compared with 1.4 percent of Verizon customers.
    The figures stand in contrast with quality of service however, specifically in terms of dropped calls.

Sony CEO leak plans for 8MP iPhone 5 camera

4/05/2011 04:46:00 PM 0
Sony CEO leak plans for 8MP iPhone 5 camera
   Sony chief Sir Howard Stringer may have unintentionally given away plans for an eight-megapixel camera in the iPhone 5. During an interview with the WSJ's Walt Mossberg, he claimed that the company's camera sensor plant in Sendai had seen hit by the Japanese earthquake and that shipments of sensors to Apple would be delayed. Apple has so far only sourced cameras from OmniVision, suggesting that Sony was shipping for a future model.


    Apple might have been eying Sony's new Exmor R camera sensors, as found in the Sony Ericsson Xperia arc , and the recently announced Xperia neo. The 8MP camera sensor there is backlit, which helps it cope with low light situations, similar to what the current 5MP OmniVision

Sunday, April 3, 2011

SS7 Basics

4/03/2011 04:15:00 PM 0
SS7 Basics
SS7 Protocol :


     The primary signaling protocol in use today is signaling systems 7(SS7), which interconnects networks such as SSP, SCP .

     The SS7 Protocol stak consist in several individual protocols, including Message Transfer Part (MTP) level1,2 and 3, Integrated services Digital Network User Part, Signaling Connection Control Part (SCCP), and the Transmission Capabilities Application Part (TCAP) working together, these protocols define the format for all SS7 messages, as well as the procedures by which messages are generated and processed.
    

IEEE approve next generation 802.16m WiMAX standard

4/03/2011 12:46:00 PM 0
IEEE approve next generation 802.16m WiMAX standard
    The IEEE Standards Association has given its seal of approval to the next generation WiMAX standard, dubbed 802.16m. The new standard supports a “wide range of data rates in multiple user environments” and has a theoretical maximum throughput of around 300Mbps.



     ” The standards group notes that 802.16m will provide the speed and performance necessary to support future advanced services and applications for next generation broadband mobile communications.”  said Dr. Roger Marks, Chairman of the 802.16 Working Group.

Wednesday, March 30, 2011

BlackBerry Touch (Monaco / Monza) hands-on -- New !

3/30/2011 12:25:00 PM 0
BlackBerry Touch (Monaco / Monza) hands-on -- New !
    Boy Genius Report revealed a few leaked photos of the company’s latest evolution of a full touchscreen device, the BlackBerry Monaco / Monza.



     The handset boasts BlackBerry OS 6.1 and users reportedly need a BlackBerry ID to login, which might be tied to other cloud services.

    The new device, most likely not a member of the Storm family is a thinner, faster and sexier BlackBerry handset.
   

Tuesday, March 29, 2011

Sony Ericsson Xperia Play

3/29/2011 12:14:00 PM 0
Sony Ericsson Xperia Play
Sony Ericsson announced via its blog today that the Xperia Play has gone on sale in 11 markets around the world.


  • The world’s first PlayStation® Certified smartphone now launching to first markets
  • More than 60 games available within the first week, including top franchises Assassins Creed, Need for Speed and The Sims
  • Original PlayStation® titles available for download exclusively on Xperia™ PLAY
  • Partnerships with over 20 publishers as well as middleware companies Unity and Havok to ensure a steady flow of new innovative games

Tuesday, March 22, 2011

Useful CEH v7 Info

3/22/2011 10:33:00 AM 0
Useful CEH v7 Info





CEH v7 Exam (312-50)

Credit towards Certification Certified Ethical Hacker 7

Exam Details


Number of Questions: 150

Passing Score: 70%

Test Duration: 4 hours

Test Format: Multiple choice

Test Delivery: Prometric and VUE

Saturday, January 22, 2011

PE license and exams

1/22/2011 05:50:00 AM 0
PE  license and exams
The PE exam tests your ability to practice competently in a particular engineering discipline. It is designed for engineers who have gained at least four years’ post-college work experience in their chosen engineering discipline. The PE exam is typically the last step in the process of becoming a licensed P.E.

PE exam specifications and design standards

Agricultural
Architectural
Chemical (updated for April 2011 exam)
Civil: Construction
Civil: Geotechnical
Civil: Structural
Civil: Transportation
Civil: Water Resources and Environmental
Control Systems (updated for October 2011 exam)
Electrical and Computer: Computer Engineering

Fundamental WiMAX Concepts

1/22/2011 02:16:00 AM 1
Fundamental WiMAX Concepts
  WiMAX has four fundamental architectural components:


Base Station (BS) : 

      The BS is the node that logically connects wireless subscriber devices to operator networks. The BS maintains communications with subscriber devices and governs access to the operator networks. A BS consists of the infrastructure elements necessary to enable wireless communications, i.e., antennas, transceivers, and other electromagnetic wave transmitting equipment.

      BSs are typically fixed nodes, but they may also be used as part of mobile solutions , for example, a BS may be affixed to a vehicle to provide communications for nearby WiMAX devices. A BS also serves as a Master Relay-Base Station in the multi-hop relay topology .


Wednesday, January 19, 2011

Turbo Code Applications 2

1/19/2011 01:16:00 PM 0
Turbo Code Applications 2
Terrestrial telephony: 
 
    Turbo codes are suited for down-to-earth applications such as terrestrial telephony. Satellite technology provides global coverage and service. UMTS is being standardized to ensure an efficient and effective interaction between satellite and terrestrial networks. 

    An important third generation cellular standard is cdma2000, which is standardized by the third generation partnership project (3GPP). As in UMTS (Universal Mobile Telephone Service), cdma2000 systems use turbo codes for forward error correction (FEC). While the turbo codes used by these two systems are very similar, the differences lie in the interleaving algorithm, the range of allowable input size and the rate of constituent RSC encoders. 

Turbo Code Applications 1

1/19/2011 01:14:00 PM 0
Turbo Code Applications 1

Mobile radio: 
 
     Few environments require more immunity to fading than those found in mobile communications. For applications where delay vs performance is crucial, turbo codes Offer a wide trade-off space at decoder complexities equal to or better than conventional concatenated code performance. The major benefit is that such systems can work with smaller constraint-length convolutional encoders. The major drawback is decoder latency. Turbo codes with short delay are being heavily researched. Turbo codes generally outperform convolutional and block codes when interleavers exceed 200 bits in length. 

Digital video: 
 

Motorola i886

1/19/2011 12:11:00 PM 0
Motorola i886
    The Motorola i886 is a very solid candybar phone coated in soft touch paint for a quality feel. It has a 2.2” QVGA display with 262K colors with an ambient light sensor. The display is good enough; smaller text sometimes looks a bit choppy but is readable and the screen can be used in most lighting conditions with little issue. Below it is a traditional 12 key dialpad with navigation cluster. The 5-way directional pad has three buttons to either side. To the left is menu, send and notifications while to the right you’ll find home, end and back. Like most of the phone the keys are painted with soft touch and they have a good feel to them. They are prominently raised and offer good feedback and travel.


 

Samsung C3530

1/19/2011 12:07:00 PM 0
Samsung C3530
     Smartphones and big screen sizes are all the rage nowadays and even though they offer great functionality, there is still the casual user, who does not need the big screen and just wants to make a call or send a text. But hey, this does not mean that looks don't matter at all.

     The box of the Samsung C3530 contains a micro USB wall charger, standard 3.5 mm ear buds and the user manual. Nothing surprising save for the lack of a USB cable, which is rather annoying.




Nokia C3 Touch

1/19/2011 12:02:00 PM 0
Nokia C3 Touch
    This is a global GSM phone. It can be used with T-Mobile USA and AT&T.


    The design of the Nokia C3 Touch and Type borrows heavily from the higher-end C-series devices as has already been mentioned, especially the Nokia C6-01. Unlike the C6-01 however, the C3 Touch and Type feels extremely well-weighted, solid and reassuringly sturdy in the hand. With a stainless steel finish across the whole unit, it also looks much higher-end than the X3 T&T alternative. The keys are large and visually complement the rest of the phone's aesthetic which is great.


Tuesday, January 18, 2011

Introduction to 802.11 Standard

1/18/2011 02:56:00 PM 0
Introduction to 802.11 Standard
     IEEE 802.11 standard specifies a 2.4 GHz operating frequency with data rates of 1 and 2 Mbps using either Direct Sequence Spread Spectrum (DSSS) or Frequency Hopping Spread Spectrum (FHSS). The IEEE 802.11a standard specifies an OFDM physical layer (PHY) that splits an information signal across 52 separate subcarriers to provide transmission of data at a rate of 6, 9,12, 18, 24, 36, 48, or 54 Mbps. In the 802.11a IEEE standard the 6, 12, and 24 Mbps data rates are mandatory. Four of the subcarriers are pilot subcarriers that the system uses as a reference to disregard frequency or phase shifts of the signal during transmission.
 

Sunday, January 16, 2011

Basic commands and syntax in MATLAB

1/16/2011 12:46:00 PM 0
Basic commands and syntax in MATLAB
    We will speak about Basic commands and syntax in MATLAB to show how we can write code in it .

    If you type in a valid expression and press Enter, MATLAB will immediately execute it and return the result.

>> 2+2
ans =
           4

>> 4ˆ2

ans =
           16

>> sin(pi/2)

ans =
           1

>> 1/0


Intro to MATLAB

1/16/2011 12:30:00 PM 1
Intro to MATLAB
     MATLAB is a software package for computation in engineering, science, and applied mathematics. It offers a powerful programming language, excellent graphics, and a wide range of expertknowledge. MATLAB is published by and a trademark of The MathWorks, Inc.






     The focus in MATLAB is on computation, not mathematics. Hence symbolic expressions and manipulations are not possible (except through a clever interface to Maple). All results are not only numerical but inexact, thanks to the rounding errors inherent in computer arithmetic. The limitation to numerical computation can be seen as a drawback, but it is a source of strength too: MATLAB generally runs circles around Maple, Mathematica, and the like when it comes to numerics.

Thursday, January 13, 2011

Intro to UMTS

1/13/2011 09:56:00 AM 0
Intro to UMTS
     UMTS (Universal Mobile Telecommunications Service) is a third-generation (3G) broadband, packet-based transmission of text, digitized voice, video, and multimedia at data rates up to 2 megabits per second (Mbps). UMTS offers a consistent set of services to mobile computer and phone users, no matter where they are located in the world. 



   

Wednesday, January 12, 2011

What's OFDM-MIMO ?

1/12/2011 11:11:00 AM 1
What's OFDM-MIMO ?
 Multiple Input Multiple Output (MIMO)

     One building block for next-generation wireless access, MIMO (multiple-input, multiple-output), is an advanced antenna technology that can carry 4 to 5 times more data traffic than today’s most advanced UMTS-HSDPA-ready (3G) networks. A network design incorporating MIMO technology provides the scalability needed to quickly deliver multimedia content to the mass market. With MIMO, for example, a ½ megabit picture can be downloaded in a half second or a 30-megabit video in half a minute. 

We know that there are 4 types : SISo , SIMO , MISO and MIMO  


SISo : Single i/p , Single O/p
SIMO : Single i/p , Multi o/p
MISO : Multi i/p , Single o/p

         

OFDM Advantages and Disadvantages

1/12/2011 11:01:00 AM 1
OFDM Advantages and Disadvantages
    The major advantage of OFDM is its robustness against multi path propagation. Thus, it is suitable to be implemented in wireless environments. The introduction of cyclic prefix made OFDM system resistance to time dispersion. OFDM symbol rate is low since a data stream is divided into several parallel streams before transmission. This make the fading is slow enough for the channel to be considered as constant during one OFDM symbol interval.



   

Orthogonal Frequency Division Multiplexing (OFDM)

1/12/2011 10:46:00 AM 1
Orthogonal Frequency Division Multiplexing (OFDM)
      Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier modulation technique. OFDM provides high bandwidth efficiency because the carriers are orthogonal to each other and multiple carriers share the data among themselves. The main advantage of this transmission technique is their robustness to channel fading in wireless communication environment.

     OFDM is an attractive modulation scheme used in broadband wireless systems that encounter large delay spreads. OFDM avoids temporal equalization altogether, using a cyclic prefix technique with a small penalty in channel capacity.
  
     

Using SC-FDMA in LTE

1/12/2011 02:51:00 AM 0
Using SC-FDMA in  LTE

     Single carrier frequency division multiple access (SC-FDMA) has been adopted by the third generation partnership project (3GPP) for uplink transmission in technology standardized for long term evolution (LTE) of cellular systems.SC-FDMA was chosen because it combines the low PAPR techniques of single-carrier transmission systems, such as GSM and CDMA, with the multi-path resistance and flexible frequency allocation of OFDMA. 
 
     Data symbols in the time domain are converted to the frequency domain using a discrete Fourier transform (DFT).Then in the frequency domain they are mapped to the desired location in the overall channel bandwidth before being converted back to the time domain using an inverse FFT (IFFT).

     

Sunday, January 9, 2011

Turbo-Decoder

1/09/2011 12:22:00 PM 0
Turbo-Decoder

      The turbo code decoder is an iterative Maximum A posteriori (MAP) algorithm. MAP algorithms use a Bayesian analysis of the channel transition probabilities and the state diagram of the encoder to estimate the most likely transmitted sequence of data bits based on the received sequence of data and code bits. The decoder sequentially decodes the results from each constituent encoder. 

      The results of each of these steps are fed to the next step as a-priori information called extrinsic data. After processing the results of all constituent codes, the algorithm goes back to the first constituent code and repeats the process see Figure below.

Turbo-Encoder

1/09/2011 12:16:00 PM 0
Turbo-Encoder

     Turbo code encoders are a concatenation of systematic encoders referred to as constituent codes. (Systematic encoders pass both uncoded data and code bits.) The data is grouped into blocks before coding. Many variations of concatenation have been used: e.g., parallel, serial, and product codes.The figure is an example of a two-constituent code, parallel concatenated turbo encoder.


     

What's the Turbo-code ?

1/09/2011 12:10:00 PM 0
What's the Turbo-code ?

       Turbo coding is a forward error correction (FEC) scheme. Iterative decoding is the key feature of turbo codes. Turbo codes consist of concatenation of two convolution codes. Turbo codes give better performance at low signal to noise ratio (SNR). 

       Interestingly, the name Turbo was given to this codes because of the cyclic feedback mechanism (as in Turbo machines) to the decoders in an iterative manner.The turbo encoder transmits the encoded bits which form inputs to the turbo decoder. The turbo decoder decodes the information iteratively. Turbo codes can be concatenated in series, parallel or in a hybrid manner. Concatenated codes can be classified as parallel concatenated convolutional codes (PCCC) or serial concatenated convolutional codes (SCCC). 

       In PCCC two encoders operate on the same information bits. In SCCC, one encoder encodes the output of another encoder. The hybrid concatenation scheme consists of the combination of both parallel and serial concatenated convolutional codes. The turbo decoder has two decoders that perform iterative decoding. 

we will speak about Encoder next post then Decoder

Monday, January 3, 2011

Frequency Concepts in GSM

1/03/2011 07:52:00 PM 0
Frequency Concepts in GSM
      An MS communicates with a BTS by transmitting or receiving radio waves, which consist of electromagnetic energy. The frequency of a radio wave is the number of times that the wave
oscillates per second. Frequency is measured in Hertz (Hz), where 1 Hz indicates one oscillation per second. Radio frequencies are used for many applications in the world today.
Some common uses include :
                           • Television  --------------> 300 MHz approx.
                           •  FM Radio  --------------> 100 MHz approx.
                           •  Police radios  ----------> Country dependent.
                           •  Mobile networks  ------> 300 - 2000 MHz approx

      The frequencies used by mobile networks varies according to the standard being used2. An operator applies for the available frequencies or, as in the United States, the operator bids for frequency bands at an auction.

Messages in CDMA

1/03/2011 11:13:00 AM 1
Messages in CDMA
 I want to speak about messages in CDMA , how it sent and what the call processing

**  In CDMA, most call processing events are driven by messages.
** Some CDMA channels exist for the sole purpose of carrying, they never carry user’s voice traffic.
          • Sync Channel (a forward channel).
          • Paging Channel (a forward channel).
          • Access Channel (a reverse channel).
          • On these channels, there are only messages, continuously all of the time.
** Some CDMA channels exist just to carry user traffic.
          • Forward Traffic Channel.
          • Reverse Traffic Channel.
          • On these channels, most of the time is filled with traffic and messages are sent only when there is something to do.
** All CDMA messages have very similar structure, regardless of the channel on which they are sent.


Sunday, January 2, 2011

Adv. & DisAdv. of GSM and IS-95

1/02/2011 05:11:00 PM 0
Adv. & DisAdv. of GSM and IS-95
Advantages of 2G GSM

  • GSM is mature; this maturity means a more stable network with robust features.
  • Less signal deterioration inside buildings.
  • Ability to use repeaters.
  • Talktime is generally higher in GSM phones due to the pulse nature of transmission.
  • The availability of Subscriber Identity Modules allows users to switch networks and handsets at will, aside from a subsidy lock.
  • GSM covers virtually all parts of the world so international roaming is not a problem.
  • The much bigger number of subscribers globally creates a better network effect for GSM handset makers, carriers and end users.
Disadvantages of 2G GSM

  • Pulse nature of TDMA transmission used in 2G interferes with some electronics, especially certain audio amplifiers. 3G uses W-CDMA now.
  • Intellectual property is concentrated among a few industry participants, creating barriers to entry for new entrants and limiting competition among phone manufacturers.[citation needed]
  • GSM has a fixed maximum cell site range of 35 km, which is imposed by technical limitations.[2]

An intro to WiMAX

1/02/2011 12:36:00 AM 0
An intro to WiMAX
WiMAX (Worldwide Interoperability for Microwave Access) ( 802.16 - 802.16e )



     It was defined by the WiMAX Forum is a telecommunication protocol that provided fixed and fully mobile broadband access (IEEE 802.16e ). WIMAX was developed to promote conformance and interoperability of the IEEE 802.16 standard (Wireless MAN). Meanwhile WIMAX Forum is the organization which dedicated to certifying the interoperability of broadband wireless access (BWA). WIMAX Forum will conduct the testing to ensure that different mobile broadband system from many manufactures work properly.

    

Saturday, January 1, 2011

Secret codes for Samsung

1/01/2011 05:30:00 PM 0
Secret codes for Samsung
*#1111#          ------->      S/W Version
*#1234#          ------->      Firmware Version
*#2222#         
------->      H/W Version
*#8999*8376263# 
---->   All Versions Together
*#8999*8378#  
------->    Test Menu
*#4777*8665#  
------->    GPSR Tool
*#8999*523#    
------->    LCD Brightness
*#8999*377#    
------->    Error Menu
*#8999*327#    
------->    EEP Menu
*#8999*3825523# 
---->   Don't Know.
*#8999*667#    
------->    Debug Mode
*#92782#         
------->    Phone Model (Wap)

GSM NETWORK COMPONENTS

1/01/2011 05:00:00 PM 1
GSM NETWORK COMPONENTS
   The GSM network is divided into two systems. Each of these systems are comprised of a number of functional units which are individual components of the mobile network. The two systems are:
              • Switching System (SS)
              • Base Station System (BSS)
    In addition, as with all telecommunications networks, GSM networks are operated, maintained and managed from computerized centers.

AUC     Authentication Center

GSM PHASES

1/01/2011 04:52:00 PM 2
GSM PHASES
    In the late 1980s, the groups involved in developing the GSM standard realized that within the given time-frame they could not complete the specifications for the entire range of GSM
services and features as originally planned. Because of this, it was decided that GSM would be released in phases with phase 1 consisting of a limited set of services and features. Each new
phase builds on the services offered by existing phases.

Phase 1

   Phase 1 contains the most common services including:
          • Voice telephony
          • International roaming
          • Basic fax/data services (up to 9.6 kbits/s)
          • Call forwarding
          • Call barring
          • Short Message Service (SMS)
 

Basics of Optical Fibers

1/01/2011 04:24:00 PM 2
Basics of Optical Fibers
    A fiber-optic system is similar to the copper wire system that fiber-optics is replacing. The difference is that fiber-optics use light pulses to transmit information down fiber lines instead of using electronic pulses to transmit information down copper lines. Looking at the components in a fiber-optic chain will give a better understanding of how the system works in conjunction with wire based systems.


    At one end of the system is a transmitter. This is the place of origin for information coming on to fiber-optic lines. The transmitter accepts coded electronic pulse information coming from copper wire. It then processes and translates that information into equivalently coded light pulses. A light-emitting diode (LED) or an injection-laser diode (ILD) can be used for generating the light pulses. Using a lens, the light pulses are funneled into the fiber-optic medium where they travel down the cable. The light (near infrared) is most often 850nm for shorter distances and 1,300nm for longer distances on Multi-mode fiber and 1300nm for single-mode fiber and 1,500nm is used for for longer distances.