Monthly Archives: July 2011

What is 3G?
The third generation of wireless telecommunication technology is known as 3G. (First generation of wireless telecommunication technology is known as analog cellular, Second generation of wireless telecommunication technology is known as Digital PCS). Third generation of wireless telecommunication technology is a combination of wireless communication and Internet. 3G has super imposed the lower generations of wireless telecommunication technology in terms of design (same design is used world wide), compatible service, use of small terminals which supports Internet , Multi Media Access and Roaming. 3G is mainly used in Mobile. Using 3G technologies network operators can provide wide range of advanced services to the user with higher speed. User can now surf the internet , upload or download the data , make video call , audio and video streaming , use GPS (Global Positioning System), video conferencing at the blink of eye using 3G technologies. 3G supports IPTV (TV through the Internet) too. Using 3G in Fixed Wireless Lans data can be transferred at the speed of 5-8 Mb per second, whereas for moving device the speed may decrease. A device supporting 3G can work as computer, Television, Newspaper, ipod, Dairy, credit card etc. Using 3G technology our mobile just works like a mini computer supporting multitasking (supports different services at the same time on a same device).

What is 3G Technology?
3G the third generation of wireless telecommunication technology has given a new dimension to telecommunication industry with data transmission at lighting fast speed, more digital clarity and various multimedia services. 3G technology has made our mobile work just like a mini computer with large number of mobile applications. User can now surf the internet , upload or download the data , make video call , audio and video streaming , use GPS (Global Positioning System) at the blink of eye using 3G technologies . The main aim of 3G services is to provide user with highest speed for Data and voice transfers, GPS and other applications in secure manner. In 3G services the transmitted data is in the encrypted format only the end users can decrypt the data hence providing security to the transmitted information. 3G technology is able to provide many services because it consists of large number of Radio Technologies. 3G mostly uses CDMA and TDMA methods; FDMA is only used in DECT. According to IMT-2000 standard the following technologies can be called as 3G Technology. Code Division Multiple Access 2000 (CDMA 2000) named as IMT Multicarrier (IMT-MC) in IMT-2000 standard,Time Division Synchronous Code Division Multiple Access (TD-SCDMA) named as IMT Time Code (IMT-TC) in IMT-2000 standard, Universal Mobile Telecommunications Services (UMTS) also known as Wideband Code Division Multiple Access (W-CDMA) named as IMT Direct Spread (IMT-DS), UWC-136 named as IMT Single Carrier (IMT-SC) and Digital enhanced cordless telecommunications (DECT) named as IMT Frequency Time (IMT-FT).

Code Division Multiple Access 2000(CDMA 2000) was used to move from 2G to 3G in an efficient manner in North America. As Code Division Multiple Access 2000(CDMA 2000) is backward compatible it was easier for the providers to deploy CDMA 2000 and IS-95 in the same frequency band at the same instance of time.CDMA2000 operates on synchronous network; using synchronous network results in greater efficiency which attracted the GSM Operators. These operators were interested in utilizing an efficient network so they used CDMA2000 instead of upgrading to any other technology. Code Division Multiple Access 2000 (CDMA 2000) is used to get highest speed for data transfers with more efficiency.

Universal Mobile Telephony System (UMTS) also known as Wideband Code Division Multiple Access (W-CDMA) uses a minimum bandwidth of 5 MHz; since 5 MHz is sufficient to transmit with data rates of 144 to 384 Kbps. WCDMA provides total control on uplink and downlink i.e. can vary the data rate .WCDMA can also transmit at a data rate up to 2Mbps.This was mostly used in Europe as some frequency bands can either be used for uplink or downlink (paired bands) or both using timesharing (unpaired bands). WCDMA consist of two modes Frequency Division Duplex for paired bands and time division duplex for unpaired bands. This technology was more expensive for network operators than others as it requires new infrastructure and WCDMA is very Complex.

Time Division Synchronous Code Division Multiple Access (TD-SCDMA) was proposed by china. Time Division Synchronous Code Division Multiple Access (TD-SCDMA is a narrow frequency carrier system. And this feature of Time Division Synchronous Code Division Multiple Access (TD-SCDMA) attracts the operators as it contributes to more frequencies available for the operator. This is most fruitful for the operators with small spectrum allocations. It also increases the system (network operator system) capacity to handle more users at the same time. As name indicates Time Division Synchronous Code Division Multiple Access (TD-SCDMA) uses time division duplex system. This system can easily handle asymmetric traffic with different data rates on uplink and downlink by adjusting the timeslots for uplink and downlink. Here the uplink signals are time synchronized at base station resulting in minimum interference among the users at the same timeslot differentiated by various codes and hence increasing the capacity of the network operator system. The only disadvantage is that this system has complex hardware in order to attain uplink synchronization.

UWC-136 system also known as IMT- SC is based on Time Division Multiple Access technology and is compatible with IS-136 standard. It uses carrier of 30 KHz, 200 KHz and 1.6 MHz. The carrier of 30 KHz is compatible with IS-136. The carrier of 200 KHz transmits data at the speed upto 384 Kbps and has similar parameters as that of EDGE and GSM. This was mainly used by traffic outdoors. The carrier of 1.6 MHz transmits data at the speed upto 2 Mbps and was used as indoor.

Digital enhanced cordless telecommunications (DECT) as name indicates is the digital radio access standard for cordless communication which was developed by ETSI. The main concentration of this system was on ISDN access and telephony. This system is mainly used in small business system, corporate offices, residential systems and public cordless access systems. It is reliable and can be used in any environment it can also be used in underground mines. It works on the 1880-1900 MHz band in Europe While in other countries it uses 1900-1930 band. The band used is divided to form ten carrier frequencies and each frequency is divided to form 23 slots (time slot). Any two time slots are selected and used for communication. DECT uses TDMA/FDMA\TDD techniques. DECT provides various services like voice service, fax service, data service and multimedia service with the help of various DECT profiles. It also provides text messaging, two way communication, alarms, place locator, third party interfacing etc. With large number of features, secure communication and better voice calls DECT has become very popular around the world. On this system we can use various products like answering machines, menu driven handsets with user interface or cordless adapters. This system selects and allocates the channel dynamically and use of Time division duplex radio access method results in use of cellular systems even if they are in busy environment. Because of using the above techniques DECT can be used in various systems.

References:

1) Introduction To 3G Mobile Communication     – By Juha Korhonen

2)Wireless Networks    – By P. Nicopolitidis

3) Voice & Data Communication Handbook – By Regis J. Bates, Donald W. Gregory

0.5G was the advance version of 0G (Zero Generation or Mobile Radio Telephone system). This 0.5G technology had introduced ARP (Autoradiopuhelin) as the first commercial public mobile phone network. This ARP network was launched in 1971 at Finland.  ARP was operated on 8 Channels with a frequency of 150 MHz (147.9 – 154.875 MHz band) and its transmission power was in a range of 1 to 5 watts.  ARP used half duplex system for transmission (voice signals can either be transmitted or received at a time) with manual switched system. This Network contains cells (Land area was divided into small sectors, each sector is known as cell, a cell is covered by a radio network with one transceiver) with the cell size of 30 km.  As ARP did not support the handover, calls would get disconnected while moving from one cell to another. ARP provided 100% coverage which attracted many users towards it. ARP was successful and became very popular until the network became congested. The ARP mobile terminals were too large to be fixed in cars and were expensive too. These limitations led to invent of Autotel. Autotel are also known as PALM (Public Automated Land Mobile). Autotel is a radio telephone service which in terms of technology lies between MTS and IMTS. It used digital signals for messages like call stepup, channel assignment, ringing, etc only voice channel was analog. This system used existent high-power VHF channels instead of cellular system. It was developed in Canada and Columbia.

OG (Zero Generation) is also known as Mobile Radio Telephone system. As this generation was invented prior to cellular system it was mentioned as pre cellular system. This system was analog in nature i.e. analog signals were used as carriers. Generally Mobile Radio Telephone system provides half duplex communications i.e. only one person will speak and other should hear. Mobile Radio Telephone system (Zero generation) consists of various technologies such as Advanced Mobile Telephone System (AMTS), Mobile Telephone System (MTS), MTD (Mobile telephony system D), OLT (Offentlig Landmobile Telefoni or Public Land Mobile Telephony), Push to Talk (PTT) and Improved Mobile Telephone Service (IMTS).These mobile telephones were placed in vehicles (truck, cars etc). The mobile telephone instrument had two main parts those were transceiver (transmitter – receiver) and head (instrument which had display and dial keys). Transceiver (transmitter – receiver) was fixed in the vehicle trunk; head was fixed near the driver seat and both head and transceiver were connected to each other with wire. The device (telephone) would connect to local telephone network only if it is in the range of 20 Kms. Each city had a central antenna tower with 25 channels. This means that mobile transceiver should have a powerful transmitter with a transmitting range of 50-70 Kms. Only few people were able to use this device as only 25 channels were available. Roaming facility was not supported in this generation of analog cellular Mobile Radio telephone system. Mobile Radio telephone system was a commercial service under public switched telephone network with unique telephone numbers. Zero generation had seen different variants of two way radio telephones. Large number of limitations in this generation led to the advent of new generation.

What is 0.5G Technology?

0.5G was the advance version of 0G (Zero Generation or Mobile Radio Telephone system). This 0.5G technology had introduced ARP (Autoradiopuhelin) as the first commercial public mobile phone network. This ARP network was launched in 1971 at Finland.  ARP was operated on 8 Channels with a frequency of 150 MHz (147.9 – 154.875 MHz band) and its transmission power was in a range of 1 to 5 watts.  ARP used half duplex system for transmission (voice signals can either be transmitted or received at a time) with manual switched system. This Network contains cells (Land area was divided into small sectors, each sector is known as cell, a cell is covered by a radio network with one transceiver) with the cell size of 30 km.  As ARP did not support the handover, calls would get disconnected while moving from one cell to another. ARP provided 100% coverage which attracted many users towards it. ARP was successful and became very popular until the network became congested. The ARP mobile terminals were too large to be fixed in cars and were expensive too. These limitations led to invent of Autotel. Autotel are also known as PALM (Public Automated Land Mobile). Autotel is a radio telephone service which in terms of technology lies between MTS and IMTS. It used digital signals for messages like call stepup, channel assignment, ringing, etc only voice channel was analog. This system used existent high-power VHF channels instead of cellular system. It was developed in Canada and Columbia.

High Speed Uplink Packet Access (HSUPA) also known as 3.75 G (3.75 generation of wireless telecommunication technology) is a protocol which aims at providing higher uplink speed equals to 5.8 Mbps. HSUPA is related to group of protocols from HSPA (High Speed Packet Access) as defined by 3GPP (3rd Generation Partnership Project).HSUPA protocol name is baptized by nokia however 3rd Generation Partnership Project(3GPP) calls it as Enhanced Uplink (EUL).Working of HSUPA is similar as that of HSDPA with the only difference that HSDPA protocol provides high speed of downlink and HSUPA protocol improves the uplink speed by increasing the throughput , capacity and decreasing delays. HSUPA works on request grant principle in which user will seek permission from scheduler to transmit data (data is send in packets), scheduler then decides at what time the user can send data and number of users who will be permitted to send data. HSUPA permits non-scheduled modes. In non-scheduled modes the users can self-initiate transmission like Voice Calls or Multi-media sessions. HSUPA introduces a new channel named as Uplink Enhanced dedicated channel (E-DCH) which uses link adaptation methods like Shorter Transmission Time Interval results in faster link adaptation and Hybrid automatic repeat request (HARQ) results in effective retransmissions. Using these techniques the mobile phone and network can communicate at faster speed. HSUPA also has a new feature called as multi-code transmission; using this feature the user can find increase in the uplink speed. HSUPA includes new channels like F-DPCH (Fractional-DPCH), E-AGCH (Absolute Grant Channel), E-DPCCH (E-DCH Dedicated Physical Control Channel), E-HICH (E-DCH Hybrid ARQ Indicator Channel), E-DPDCH (E-DCH Dedicated Physical Data Channel) and E-RGCH (Relative Grant Channel). E-DPDCH (E-DCH Dedicated Physical Data Channel) carries the E-DCH Transport Channel whereas E-DPCCH (E-DCH Dedicated Physical Control Channel) transmits the  information concerning to E-DCH.

What is the difference between HSDPA and HSUPA?

• HSDPA improves the speed of downlink data transmission.HSUPA improves the speed of uplink data transmission.

• In HSDPA code space and the transmission power are the shared sources which are controlled by Node B.In HSUPA the amount of allowed uplink interference is the shared resource.The amount of allowed uplink interference depends on the transmission power of the individual User.

• In HSDPA the scheduler and the transmission buffers are part of the same node therefore buffer status gets updated automatically.In HSUPA the scheduler and the transmission buffers are allotted to different user therefore the User (User Equipments) needs to inform the scheduler at Node B about the buffer status.

• Adaptive Modulation is not supported by HSUPA. It only supports BPSK modulation scheme.Adaptive Modulation is supported by HSDPA.

• Using HSDPA we can listen to music online, watch videos, downloading files, can do internet browsing and much more at lightning fast speed.Using HSUPA we can upload files or seed files in a file sharing network, send emails with large attachments within few minutes.

• Generally we do more of downloading as compared to uploading so more bandwidth is allocated to HSDPA as compared to HSUPA.