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Indoor Building Distributed Antenna System (DAS)

1 Aug

Introduction & Objectives:

Indoor sites are built to cater capacity and coverage issues in indoor compounds where outdoor macro site can’t be a good solution.

In dense urban clutter where buildings structures and indoor environment losses are quite large for macro site which makes it‘s an inappropriate solution. Generally floors underground (basements and lower ground) have poor RSSI. Major part of reflections takes place from ground and because of this portion below ground have poor signal coverage.

On the other hand floors above third have quality and DCR issues. Due to fewer obstacles in the LOS path, path losses are less compared to ground floors. So there is a multiservers environment due to less path losses and cells overshooting which leads to ping pong handovers and interference issues inside the compound.

In urban areas there are buildings that generate high traffic loads like commercial buildings, offices; shopping malls may need indoor systems to take care of the traffic demands. For such areas indoor is the efficient solution regarding cost, coverage and capacity.

In indoors downlink is
the critical link in the air interface. There is no need to use the uplink diversity in an indoor system or use amplifiers like TMA for improving the uplink signal .Multi-antenna indoor system is providing diversity as uplink signals received by several antennas.

In-building solutions DAS-IBS technology is one of the fastest changes in mobile network rollouts. It has been estimated that 70-90% of all mobile calls are made inside the buildings; therefore to improve the QOS, operators today have started concentrating more on this aspect of network rollouts.

The most efficient way to achieve optimal quality, coverage & capacity result inside the building is to use Microcell with Distributed Antennae System (DAS)

Hayat Telecom LCC has set up support to Venders in rolling out IBS network & gathered both planning tools and professionals for attaining quality rollouts with utmost levels of customer satisfaction.

Indoor Building Systems Solution, Specifically the Solutions of Radio Network Design is needed to enhance QOS and Capacity of the network. Most of calls are generated from inside of buildings so it ‘does require special attention for enhancing the network performance’.

The key essentials for a potential IBS system for planning are:-

  • Identification of potential buildings for IBS.Design Distributed Antenna system using passive & active elements and, Prepare complete Link engineering diagram with each antenna’s EIRP proposal report.
  • Implementation of IBS solution with best professional way without disturbing aesthetic of building.
  • LOS & Link Planning to connect site.
  • RF parameter planning, RF walk test and call quality testing.

As moving ahead details of key part explain in detail.

Types of indoor cells:

There are mainly three types of indoor cell.

1-Micro Cells

2-Pico cells

3-Femto Cells

 

Micro cells constitute most of the indoors deployed for BTS coverage. They are more costly and also on large scale with respect to Femto or Pico cells. They consist of indoor micro /metro BTS and distributed antenna system for signal propagation in indoor environment .Usually they have passive components but where large distance to be required amplifiers especially optical amplifiers are deployed called active components.

A Pico cell is wireless communication system typically covering a small area, such as in-building (offices, shopping malls, train stations, etc.), or more recently in-aircraft. A Pico cell is analogous to a WIFI access point. In cellular wireless networks, such as GSM, the Pico cell base station is typically a low cost, small (typically the size of a sheet of A4 paper and about 2-3cm thick), reasonably simple unit that connects to a Base Station Controller (BSC). Multiple Pico cell ‘heads’ connect to each BSC: the BSC performs radio resource management and hand-over functions, and aggregates data to be passed to the Mobile Switching Centre (MSC) and/or the GPRS Support Node (GSN).

In telecommunications, a Femto cell—originally known as an Access Point Base Station—is a small cellular base station, typically designed for use in residential or small business environments. It connects to the service provider’s network via broadband (such as DSL or cable); current designs typically support 5 to 100 mobile phones in a residential setting. A Femto cell allows service providers to extend service coverage indoors, especially where access would otherwise be limited or unavailable. The Femto cell incorporates the functionality of a typical base station but extends it to allow a simpler, self contained deployment; an example is a UMTS Femto cell containing a Node B, RNC and GPRS Support Node (SGSN) with Ethernet for backhaul. Although much attention is focused on UMTS, the concept is applicable to all standards, including GSM, CDMA2000, TD-SCDMA and WiMax solutions.

Objective of IBS design:

The basic aim of indoor building solution is increasing the quality of indoor signal at different public and business locations. The Public locations are such as said before Shopping Malls, Airport terminals, Hospitals, Residential flats and business exhibition centers, Govt and private offices etc

The fig shown the obligation of IBS .With BTS site deep indoor signal penetration is not good in dense urban areas specially in high rise Building Areas.IBS cover this obligation .

IBS Design solution Scenarios:

There are various solutions that can be implemented for a particular site. For a design approach, we will select the most cost-effective solution to meet the performance criteria.

Distributed antenna network:

The useful application of antennas in indoor systems is the idea of distributed antennas.  The philosophy behind this approach is to split the transmitted power among several antenna elements, separated in space so as to provide coverage over the same area as a single antenna, but with reduced total power and improved reliability.  The smaller coverage footprint of each antenna element provides for controlled coverage and reduces excessive interference and spillage effects.

A distributed antenna system can be implemented in several ways, a number of which are listed below.

DAS-1-Passive coaxial network design:

The network is made up of passive components such as coaxial cable, combiners, splitters, directional couplers, etc. Antennas that are utilized can be of wide-bandwidth to support multi-band and/or multi-system requirements. The advantage of this approach is that the network is simple and requires minimal maintenance.

DAS -2-Leaky feeder system:

The ultimate form of a passive distributed antenna system is a radiating cable (leaky feeder) that is a special type of coaxial cable where the screen is slotted to allow radiation along the cable length. With careful design, such cables can produce virtually uniform coverage. This type of system is best suited for applications requiring in-tunnel coverage (such as in subways). The radiating cable in this case is run along the entire length of the tunnel. The cable is either a radiating coaxial cable or radiating wire.

 DAS-3-Fiber Optic Solution:

In this method, RF signals are converted to optical signals before being transmitted to distribution units via optical fibers. Single-mode and multi-mode fibers can be used but multi-mode fiber requires frequency conversion before RF- to-optic conversion. The fiber optic solution is ideal for wide-area deployments such as in buildings with extensive floor areas and high-rise office buildings. The installation cost can be well contained if the existing optical fiber infrastructure within a building can be re-used. This solution is also useful for expanding on an existing distributed antenna system that is operating on coaxial solutions.

DAS-4-Repeater Solution:

This solution is implemented to expand the coverage of an indoor or outdoor cell. If coverage is to be expanded to an isolated place, a repeater solution can be used. This input signal to the repeater can be sourced either from an existing off-the-air RF signal or fiber-fed from a remote location. In large buildings, where coaxial cable network is required to use, EBTS power will not be enough to power all the antennas. In this instance, in-line repeaters are used to boost up RF signal.

DAS-IBS Deployment Design:

Passive IBS

Mostly passive IBS is deployed as an indoor solution. Passive IBS contains splitters, couplers, attenuators, combiners, coaxial cable, DAS but there is no active element involved.

Active IBS

Active IBS is generally used when the EIRP required is more than the available. Usually this happen when distance involve are large and antenna elements are more as well. Active IBS is actually a hybrid IBS as it contains an active component (repeater) and passive IBS.

DAS-IBS-Design Entities:

Antenna:

Mostly antennas used in IBS design are Omni directional and flat panel directional antennas.The selection of antenna types is based on the availability, feasibility. Retain ability, compatibility and performance with selected solution .The usage of different type of antennas varies for different physical atmosphere. The antennas are connected with coax feeders inside the building. The antenna selection depends upon the general Product Description and specification shared by venders.

The Primary Antenna types in IBS design are:

1-Omni directional antenna

2-Directional antenna

3-Leaky cable

1-Omni Directional Antennas

It transmits signal in all direction .it contain Low gain. Horizontal direction pattern all over the place but vertical direction concentrated. General specifications of Omni Antenna as below:

Gain   2-3 dbi

Beam width 360

Polarized Vertical

VSWR  less than 1

2-Directional Antennas:

It transmits signal in a specified direction. It Contain high gain.

3-Leaky Coaxial Cable:

It transmits signal along path of the coaxial cable .Contains closely spaced slots in the outer conductor of the cable to transmit/Receive signals. There atre Two types of losses in leaky cable.

I-Feeder loss- cable attenuation loss

II-Coupling loss-Average signal level difference between the cable and dipole antenna at distance of 6m approx.

Some of the general feature reviews of antennas are given below:

Application:

-WiFi System, ISM application

 

-Indoor/in-building Coverage

 

-WLAN Communication Application

 

-CDMA, GSM, DCS, 3G/4GUMTS Application

 

-Next Gen Mobile-LTE

 

Features:

-Low return loss

-Wide beanwidth

 

-Suitable for wall mounting

 

-Low, aestheticall pleasing profile

 

Model: XXXXXXXX (Any )

 

RF Parameters:

 

-Frequency: In MHz (its selection depend upon spectrum allocation)

-Polarization: Vertical, Linear

 

-Horizontal Beam Width: 360 deg

 

-Vertical Beam Width: 90 deg (698-960MHz band (its selection depend upon spectrum allocation))

 

50 deg (1710-2700MHz band (its selection depend upon spectrum allocation))

 

-Gain: in dBi

 

-VSWR ≤ 1.5

 

-F/B >in dB

 

-Max Power: in  “W”

 

-Impedance: in Ω

 

Mechanical Specification:

 

-Radome Material ABS with UV Protection

 

-Lightning Protection Direct Ground

 

-Connector N-female

 

-Weight in  kg

 

-Size in mm

 

-Operating Temperature Range in degrees

 

-Storage Temperature in degrees

 

Different technologies antennas are available in market. Customer selects it as per need, services and requirement. i.e dual band antennas supports two band signal, quad band antennas suppots threes different band signals etc .

In addition of antennas detail as mentioned above in Passive Coaxial Cable design Distributed antennas connected with couplers, Power splitters, Jumpers and feeder cable Link Budget calculations based on how many couplers and Splitters are we used & Losses of coupler, splitters and feeder cable length in design. In the marker 20db, 15db, 10db and 6db couplers  2way, 3way and 4 way splitters  ½” inch Jumpers, ½”,7/8”,11/4” inch  feeders cables are using. Below Figures indicates how we cater losses of these coupler, splitter and cable.

Power Splitters

Splitters are used to split antenna feeder network power equally over the output ports.Two way, three way and four way splitters are generally used.

Splitters Loss:

2-Way Splitter Loss – around 3 db

3-Way Splitter Loss- around 5db

4-Way Splitter Loss- around 6db

Insertion loss for these splitters is 0 .2db.

Power Couplers:

Couplers are used to split antenna feeder power unequally among output ports.Couplers have tap/coupling loss and through loss e.g 10/0.5 coupler means its coupling loss is 10 while through loss is 5.Couplers generally are available in ratings of 3, 6, 7, 10, 15 & 20 db.

Attenuators:

Attenuators are used to reduce EIRP at antennas where less EIRP   required but the other antennas required high EIRP.

Attenuators are of values 3, 5, 7, 10 etc.

 

BTS:

The Base station capacity specification varies in Vander to Vander. The General specification of base station   is same as off Outdoor Base station or normal Base station.

Building Specifications and Coverage and Capacity Demands (Expansions): The capacity requirement enhances and fulfilled by adding extra Transceivers card into the cabinet of IBS_BTS. You can add as many card as IBS-base station supports.

For DAS-IBS coverage design regardless any type of DAS accurate building sketch and dimensions of building are very important .Designer should must required sketch map of building because defining he marked the route of cable and plan the coupler and splitter at right place without effecting KPI of deployment and coverage. For sacking this many tools in the markets are available .Mostly recommended by Vander.

Initial RF Survey:

Following are the things which are taken under consideration during initial RF Survey:

  • Site(Indoor Building) coordinates
  • Site Rough Layout sketch
  • RSSI and C/I of strong servers in different location of indoor site using TEMS pocket view mode.
  • No. of subscribers’ estimation/ floor or as the building architectural division.
  • Marking of the different areas what they are specified for.
  • Snaps of different floors
  • Building structure observation.

Initial RF survey report:

After the survey report is made in which all the above inputs are put.

 

Indoor Site Evaluation:

After the survey it is checkout if any modifications (Hard / Soft Changes) can be done to the existing neighboring site to improve the condition at the affected area. Otherwise Site is evaluated as to be an indoor Micro or wall mounted metro according to the location, requirements and conditions.

DAS-IBS Designing Tools:

iBwave Design radio planning software automates the design in-building wireless networks for optimal voice coverage and data capacity. It eliminates guesswork, to bring strong, reliable wireless communications indoors. iBwave Design is an integrated solution that takes RF designers through network planning, design, costing, validation, documentation and reporting. iBwave Design makes it easy for RF engineers to test scenarios for optimizing network coverage for 2G, 3G and 4G cellular technologies, as well as WiFi, public safety bands and femtocell.
Networks

  • RF System Design and Calculations.
  • Components Database to manage DAS equipment
  • Display DAS equipment position on floor plans
  • Create professional project documentation
  • Create automated reports on IBS project performance and cost
  • Standardize IBS design format
  • Propagation Module- Simulate indoor and outdoor propagation prediction in your building
  • Optimization module – Extrapolate outdoor wireless signals inside the building to analyze signal quality and data throughput before design phase
  • Collection module- import survey data and trace routes from collection devices, and overlaying survey data onto wireless indoor network design.
  • RF professionals to manage complex in-building network projects, generating cost efficiency, increasing productivity and delivering a larger return on investment.
  • Below address may help us to review and finalize designing tools. We can ask the IBS design module quotations to all RF Tools Venders after mailing info@ to all link presents..


Planning Tools for Wide Area Wireless Systems

Radio Planning Tools
Mentum Planet ™
Mentum CellPlanner ™
Forsk Atoll
ASSET
Broadband Planner
CelPlan 
WinProp
V-Soft Probe
EDXWireless
x-Wizard

Overture

iBwave

CRC-COVLAB

FUN

Hi-Res

MbP

RedPredict

TAP

RFCAD

Astrix

ComSite

 

RF Survey with floor Plan:

Once the indoor site is finalized, floor Architectural Plans are requested from building Authorities.

RF survey with Floor Plans is carried, RSSI is checked & recorded at each and every part of the indoor environment and C/I is checked at worst.

Drive test tool idle mode log files for different floors are made using floor plans provided.

During the RF survey Detailed Analysis/Observations of the building/environment is carried out as well as what is the ceiling thickness, floor heights, thickness of the walls in between floors, thin walls and their thickness.

Antenna locations are finalized using traditional Ray tracing techniques(By simply analyzing how reflections and propagation going to occur)

Fig  RSSI of different servers with floor plans

Marking of Priority Area:

In indoor areas like offices and meeting rooms etc have usually high priority. On the other hand areas like mosques, gyms etc have low priorities. Similarly area in which outdoor macro coverage and quality is satisfactory should not be included in intended coverage area for indoor site. For high priority area coverage should be around -75 dbm at each point while for low priority area levels should be around -85 dbm. These values vary according to KPI’s doc of the network.

Fig : Priority area marking for an indoor site location

Indoor Antenna Placement:

Antenna placement is the most crucial step in indoor planning. Following observations should   be considered during antenna placement:

  • Antennas especially Omni-directional antennas should be placed at centralized locations.
  • Panels should be placed in the corners of corridors or where design demands while keeping in view the spillage of indoor signals.
  • Antennas should be placed at high elevations where people can’t touch them as it will affect the performance.
  • Obstacle free path should be provided for antennas otherwise coverage in indoor will suffer a lot.
  • Antennas should be placed away from conductive objects.
  • Exposure levels of the indoor RF signals are below RF safety standard of WHO, IRPA, IEEE and FCC. However discretely placed antenna will reduce the unnecessary public concerns about RF exposure.
  • If the building with low traffic capacity is to be planned antennas should be placed in zigzag manner such to get an even distribution of signals as depicted in fig. below

Fig :  Improvement in indoor coverage

Link Budget:

Link Budget calculations are used to calculate the output power (db) at each antenna element. Passive component (coupler, splitter and attenuator losses) and feeder cable losses are subtracted from BTS output power. Link budget calculations are made for band to be used for indoor GSM/DCS/UMTS.

EIRP= Pout BTS + Ga – Lf – Lc- Ls – La

Pout BTS= BTS output power at antenna connector

Ga= Antenna gain (db)

Lf= Feeder loss

Lc= Coupler loss

Ls= Splitter loss

La= Attenuator loss

With standard parameters we can calculate link budget of the access site shared by Vander side

RF Indoor Plan:

After the path loss and link budget calculations RF plan is made floor by floor on the autocad layout of the building. Care should be taken while adjusting the AutoCAD scale. Also antenna, cable lengths and passive elements should be drawn accurately according to the plan.

Fig : RF indoor Plan for a floor

Antenna tree diagram:

Antenna tree diagram is made to have a quick overview of the IBS design. Care should be taken while calculating the lengths.

 

Fig 5.18: Antenna Tree diagram

Fig : Measurements for Cable lengths

Indoor Equipment List:

Detailed and complete BoQ list essential at site.

Fig: Indoor Equipment List

Indoor Site frequency planning:

Frequency planning is performed manually selecting suitable frequencies by carefully analyzing the neighboring frequencies.Exclude the co-channel and adjacent frequencies which will likely to interfere.From the remaining set choose the frequency that most likely to cause interference. BCCH frequency should be the least disturbed. Hopping on several frequencies will smooth out the interference.

Following need to be considered if two much clean frequency options exist:

  • Increase signal strength of indoor cell.
  • Allocate dedicated 3-5 frequencies for indoor cells.
  • Redesign the frequency plan.
  • (Indoor sites in our network are single cell; single band sites, so no frequency reuse is done in indoor)

IBS System Deployment Recommendations:

Traditional IBS deployment as said before Passive and active DAS –IBS.
Operators deploy solutions as per regulatory requirements (e.g. GSM or UMTS license) Recently operators deployed their own systems, single users DAS in a buildings. This resulted in multiple DAS in the same building, one for each operator (2-4) cause of

  • Multiple cable runs
  • Multiple Antennas
  • Multiple Maintenance organizations

So now a day’s regulatory authorities, building developers/owners and operators are

More operators are in force of sharing the IBS DAS. As illustrated before, all operators can share one DAS which cause of less cables and antennas and Shared maintenance efforts which helps controlling apex of IBS-DAS. This equals less negative impact on the esthetics of the building, less maintenance activities and lower cost for DAS.

The Third party installs the DAS most of the times. Generic Multi Operator DAS implemented by developer/owner in a building. DAS connected with Coaxial cables  with star configuration, Antennas (location based on generic guidelines, cables routed back to the nearest technical room e.g. maximum 90 meter cable run.

Wireless Design Simplicity

Goal – Provide a “-75dBm Coverage Blanket”for meeting coverage ,QOS KPI’s.

The Antenna Location Design Rules:

  • Outside antennas within 20ft of the edge of the building
  • Antennas spaced at 100 ft apart
  • One antenna per floor within 20 ft of the elevator core
  • One back-to-back antenna every 6 floors in the elevator shaft starting on floor 3
  • Cable: Star configuration

Following rules of thumb Maximum flexibility for the future RF planning

  • Omni antennas on a basic 100ft (30m) grid
  • Perimeter antennas < 20ft (6m) from walls
  • If on external wall, utilize directional antenna
  • One antenna < 20ft (6m) from elevator core

  

 

Stairwells:

  • If open, Omni antenna every 6th floor,
  • If closed, Omni antenna every 2nd floor

Installation & Certification:

  • Each cable run directly to TR < 300ft (90m)
  • Install connectors on both ends
  • Sweep-test for integrity and loss
  • Attach antennas & document cable paths
  • Extended warranty

Site Acceptance:

Once the indoor site is implemented site acceptance request is made by vendors/sub cons. Implementation team will take care of VSWR calculations, antenna grounding etc. Following is required from RF Team for acceptance of the indoor site:

  1. On site Audit
  2. Walk test
  3. Spillage check

1-On Site Audit:

On site verification of the indoor is performed to check the antenna location as well as the equipment count.

2-WALK TEST:

Walk test summarizing the coverage actual manners. It will be tested at two  types of  drive test mode

I-Idle Mode:

Walk test in idle mode for the indoor site is performed to check the RSSI and C/I of indoor site. Logfiles are made on the floor plans provided. (In case of vendor planning walk test  report is to be provided by them).

Fig : Rx-Level Idle mode

II-Dedicated mode:

Dedicated mode walk test is performed to check the quality and RSSI of indoor after call setup. Qualities of different TRX are also checked at RF end by locking the call on different TRX’s. Also handovers with other neighboring sites is tested.

Fig : Rx-Qual Dedicated mode

III-Spillage Check:

Spillage is spill of indoor signal outside the indoor location. Spillage is generally checked 20m away from the periphery of indoor compound. Generally -85dbm is set as a threshold and levels below it are problematic   as they will cause unnecessary handovers on the indoor site. However using Cell Reselection Offset parameters and handover control parameters, the unnecessary reselections and handovers can be avoided.

Fig Spillage

4-Coverage Acceptance:

Coverage is checked at each part of the indoor compound and should be within the range.

5-VSWR:

To be checked by implementation.

6-Parameters fine tuning:

Before site is accepted by the planning team Fine tuning of parameters is performed to achieve the below mentioned KPI’s. After achieving the KPI targets planning will accept this and handed over to optimization team for further fine tuning

KPIs
1 RX Level for 2G for 95% of the Covered Area=-75dBm
2 RSCP for 95% of the Covered Area=-80dBm
3 DL Rx Quality for 2G for 95% area of the covered Area less than 2

 

Pilot power  of 3G common area  less than -75 dBm

Pilot Ec/Io of common area  less than -7 dBm

Spillage Test (On the surrounding main street nearby the building)

1

Signal from indoor system not higher than -95dBm

 

Frequency Planning for Indoor Systems Conclusion:

For improve coverage and Capacity inside building using IBS solution and it shows an increase of the cellular traffic with up to 70% for larger buildings. For good coverage we have to assign frequencies manually by excluding the frequencies of the Surrounding cells and the adjacent frequencies. For avoiding interference it is good to apply Frequency Hooping to smooth out the interference. It is good for coverage if we are increasing the BTS power if the available frequencies are few in numbers.

h

IBS Planning & Implementation:

To starting planning process of IBS DAS Statically review of the network is very important and essential .The identification of the right area or building for IBS DAS design very critical .Once the Area identified with help of stats of the network, field visits and complains.

Once location identified standardized planning ladder followed till all entity of DAS IBS design practical implemented.

Conclusion:

In-building Solutions as defined in this document is a way to enable efficient usage of wireless mobile applications inside different kinds of buildings. This requires that sufficient coverage and capacity with good radio quality is available inside the buildings. Although the mobile operators will cover most buildings from outdoor sites in their macro network, there is a need to provide many buildings with extended radio coverage and capacity. In-building solutions are well-proven methods for an operator to capture new traffic and new revenue streams.

One can provide enhanced in-building solutions to off-load the macro network, thus increasing mobile traffic, and attract additional subscribers due to the enhanced mobile network quality and accessibility to mobile Internet applications and other services that require high data-rates and capacity. There are several different ways to implement in-building solutions. Dedicated Radio Base Stations, RBSs, that are connected to Distributed Antenna Systems, DASs, are commonly implemented solutions. These solutions provide additional capacity as well as covers “black holes” inside different kinds of buildings. A number of different types of both RBSs and DASs are available and the solutions can be customized for different buildings and needs. Repeaters are often used for buildings with a limited need for capacity, but where additional coverage is needed, like road tunnels and smaller buildings or parts of buildings.

Indoor systems can be solution if the coverage is weak from outdoor cells or causing to bad quality To build indoor systems into the buildings, which are generating high traffic, can reduce the network load by handling that traffic In developed business centers, indoor system can replace the fixed network.

Indoor systems are sometimes the complements that can provide a good image.

Source: http://telecom-knowledge.blogspot.nl/2014/09/indoor-building-distributed-antenna.html

3g And 4g Cellular Technologies Computer Science Essay

6 Nov

The current 3G and 4G cellular technologies cant support high data rate demands of the voice and video applications and end up providing poor coverage indoor. Customer dissatisfaction due to dropped calls and time-consuming downloads in high density metropolitan hubs were the major concerns of the service providers. A low cost solution for this problem is deployment of Femtocells in bandwidth demanding areas. The system capacity and network coverage can be increased with the use of Femtocells , which are small base stations connected to DSL or internet cable and are installed in residential or business environments. These Femtocells provide high-quality network access to indoor users, while simultaneously reducing the load of the whole system. In this seminar, architecture of Femtocells , the basic working, and its applications will be covered. The advantages of Femtocells over other networks and the technical issues in implementation of Femtocells will be discussed.

Introduction

Femtocells are small devices that can be installed in home or premises to increase the coverage capacity indoors. These femtocells are deployed in the area of very low coverage to provide the high voice and data services to the mobile devices that are assigned to femtocells initially. These femtocells are connected to mobile operator’s core network through Internet via DSL or broadband modem. Femtocells which include both a DSL router and femtocells are called . Once plugged in, the femtocell connects to the MNO’s mobile network, and provides extra coverage. From a user’s perspective, it is plug and play, there is no specific installation or technical knowledge required—anyone can install a femtocell at home.

These are also called small cells, as their coverage is very less compared to microcells (200 Km), picocells (200m), whereas Femtocells limits themselves to the range of (10m). As shown in the below figure, the femtocell deployed in home can support from 3 to 16 mobile devices. These mobile devices are operated by femtocells. The voice and data of these mobile devices is transmitted through the Femtocells network to the Mobile operators Network. As the backhauling is carried out through internet, which in turn reduces the data load from macrocell and hence increases its efficiency

Source: EMF Series Projects with Collaborations of WHO

Femtocells provide all the services such as circuit switched and packet switched services by using different architectural models. The one model is based on 3GGP standard called SIP/IMS model and the other legacy network model is based on 3GPP2 Standard. These two models are described further in more detail. Inspite of many advantages of femtocells, there are several technical issues in implementation of femtocell like handover of device, interference of cells in network and synchronization of femtocells with the network which will be dealed with in more details.

Basic Working of Femtocells: While deploying Femtocell, User declares the mobile devices that will be using the coverage area of Femtocell which is mostly done through web interface of Mobile Network operator. These defined mobile devices are when outside the coverage area of femtocell, they use the coverage of Macrocell, but as soon as the mobile device comes in the coverage are of Femtocell, the overall control of mobile device will be transferred to femtocell. The voice and data of this mobile device will be backhauled through internet to mobile operator network. The overall communication will be carried out by femtocell., and hence providing better coverage area indoors. This process of transferring the control of device from macrocell to femtocell is known as handover.

Basic Working of Femtocell

These Femtocells uses different architectures based on the Technological standards followed by Femtocells. The WCDMA uses Iuh Architecture while CDMA2000 uses SIP/IMS architecture. This network architecture share common network components.

Network Architecture Components:

Femtocell Access Point (FAP)

Security Gateway (SeGW)

Femtocell Device Management System (FMS)

Femtocell Access Point: Femtocell Access Point is a key component of femtocell architecture. These are small access points that are deployed in user location. There functions are similar to that of base station and base station controller of macrocell network. These femtocells provide connection between user equipment and mobile operator’s network. There are different types of FAP’s available some FAP’s are plug and play devices, which can be connected to the broadband routers directly. These FAP’s are also useful for prioritizing the mobile devices depending on the data being transferred by them.

Femtocell Access Points

For example, if the call is being made by any user equipment and simultaneously the song is being uploaded by any other user equipment under the same femtocell coverage area. The Mobile device with voice data will have higher priority over the device where song uploading is taking place.

Security Gateway: As the whole backhauling of data is carried over Internet, it becomes necessary to transfer the encrypted data over a secured connection to mobile operator’s network and protect the mobile devices from security breach. These security Gateway is also used to authenticate all the mobile devices that are allowed to use femtocell services. When any initially defined mobile device comes under the coverage of femtocell network it is first authenticated before allowing it to use femtocell services. The encryption of data and signaling is carried out using standard Internet protocol such as IPSEC and IKEv2.

The security gateway is a network node that secures the Internet connection between femtocell users and the mobile operator core network.  It uses standard Internet security protocols such as IPSec and IKEv2 to authenticate and authorize femtocells and provide encryption support for all signaling and user traffic.

Femtocell Device Management System: As there is large number of femtocells, it is necessary to manage the devices and operation of all the femtocells, this is done by femtocell device management system. It is resides in operator’s network. The FDMS is use to configure the different devices available and manage the operation of each device with respect to other from the operator’s core network. This plays a key role in initiatilisation and activation of femtocells when deployed for the first time and continues providing it services of updating and configuring newly available services. For managing such large number of femtocells specific architecture called clustering and load balancing is used. The basic standard used by femtocell network management system is TR-069.

As shown in below figure, depending on the functionality, the FSM is classified further in two parts.

1. Automatic Network Planner: It is use to plan the allocation of carrier frequency for femtocell. It executes the Frequency Reuse algorithm, RF Planning algorithms and configures the best RF to the femtocell avoiding the interference with neighbouring femtocell.

2. Device Manager: Unlike Automatic Network Planner, it is associated with femtocell devices at user end. Its basic functions are error detection and management in femtocells devices, remote configuration and diagnostic, upgrading the software versions on the devices, collecting the performance information in particular.

Femtocell Service Management System

Architectural Models:

SIP/IMS Network Model

Legacy Network Model

1. SIP/IMS Network Model: In SIP/IMS model, when the call is made from the mobile devices, the signaling and encrypted data is carried out from femtocell to the IMS network architecture via security gateway and then forwarded to PSTN network. The following are the important components of architecture.

Femtocell Access Point (IMS Client)

SIP/IMS Core Network

Femtocell Convergence Server (FCS)

Legacy Network Model

This network does all the call routing and signaling functions. The Voice data from the femtocell access point is converted over RTP and then transmitted to femtocell convergence server. The 3G signaling is converted to IMS signaling. The nodes of SIP/IMS network consist of Home subscriber subsystem which provides the information of subscriber, Call signaling control function, manages all the signaling functions, Media gateway controller which connects to Legacy Network. The other most important component is femtocell convergence server which is an application server and it connects to MSC(mobile switching center) in legacy network using an IS-41 network interface and is connected to CSCF using standard ISC interface.

Femtocell Convergence Server also acts as MSC for mobile core network. It also conducts handover between femtocell and macrocell. When a mobile device moves from femtocell coverage to macrocell network coverage, macrocell to macrocell hand off mechanism is used and hence femtocells receive messages same as they are received when macrocell to macrocell handoffs takes place.

Below is the complete description of network blocks in SIP/IMS Architecture.

SIP/IMS Network Model

2. Legacy Network Model: This is the simple network model compared to SIP/IMS model as it allows the use of already existing mobile operators network.

The three important components of Legacy network model are

Femtocell Access Point

Femtocell Network Gateway (FNG)

Security Gateway

This model connects to mobile operator’s network directly through FNG (femto network gateway). These femto network gateway connects the actual FAP’s using standardize 3GPP Iuh interface to the Legacy network. FNG acts as a mobile radio network controller for femtocells. In this model the handoff is carried out by MSC of core network. In this model support of active handoff is given through the legacy MSC. When the femtocell moves from femtocell coverage to macrocell network the handoff mechanism is carried in the way similar to that between radio network controller and MSC, using the Iu interface. The legacy network model is used by 3GPPstandards for UMTS femtocells.

Legacy Network Model

The FCS and FMS mentioned above plays a very important role in setting up a call as act as mediator between the femtocell and mobile operator core network. The packet data services are provided by network components such as SGGSN/GGSN in UMTS and PDSN in CDMA femtocells. Femtocells are connected directly to SGGSN while for connecting to PDSN, FNG acts as bridge between them.

Advantages:

1. Good Coverage and increased data capacity: For the good coverage and data transfer capacity, the ratio of signal to Noise should be high enough to sustain the attenuation that occurs when a signal is transmitted from macrocell to the receiver. As the data rate of voice signal is 10kb/s compared to that of data traffic which is in Mbps, the requirement of signal strength for voice traffic is also less compared to data traffic. As the use of Smart phones is substantially increase from last few years, these high data rates could not be gained due to high attenuation that takes place during transmission of signal between transmitter and receiver. As the signal attenuation is caused mainly due to shadowing, interference from other transmitters and path loss causing the decaying of signal. The signal decay is given as D=A.d-α A is the constant loss, d is distance between transmitter and receiver and α is the decay constant. So in order to minimize the path loss d should be decreased.

Increased Spectral efficiency

Femtocell overcomes this issue as the transmitter is installed in the home/premises and the receiver that will be the mobile devices will also reside at very short distance from the transmitter. Hence decreasing the distance between transmitter and receiver, will decrease the attenuation of signal and hence will avoid the signal to noise ratio to degrade. As low power is required by femtocells to operate, which eventually increase the battery life of mobile device. Mobile device will require very less power to be transmitted and hence more number of mobile devices can be used in small coverage area of femtocell. This increase in the number of mobile devices increases the overall spectral efficiency.

2. Offloading Macrocell: As the back hauling of data is carried out by femtocell the load on the macrocell is comparatively reduce. The whole control of data and all the data transfer of a mobile device take place through the femtocell. The backhauling data through Internet provides better capacity to mobile device, simultaneously reducing the data uploaded directly to Macrocell radio network. Hence the mobile base station can provide god coverage and capacity to other mobile devices that are not under the coverage area of Femtocell. The mobile base station can provide coverage to more number of mobile users in its cell area. This will be advantageous to service provider as well as subscriber. Subscriber can enjoy high data capacity and coverage area and simultaneously reducing the overall burden on the macrocell and hence improving macrocell reliability.

3. Self Organising: The Femtocell can be easily installed by non technical user. It has to be ‘plug and play’. Femtocells automatically get configured to available network environment. Any operational changes even after installation are detected and the femtocell device gets updated. Femtocell are capable of detecting and managing fault during operation. It is self configuring, self optimizing, error detecting and rectifying device. They basically work on self organizing algorithms which are executed by device manager.

4. Cost effective: It has been observed that 70% of total data transfers take place indoors. In order to provide good coverage indoor it is necessary for service providers to install more base station as the number of mobile users is increasing. Installing the macrocell basestaton is very costly and requires huge infrastructure. Installing macrocell will not be efficient way to increase the coverage indoors, as there is 20db loss of signal due to the infrastructure, fading etc. Femtocell deployments will costs above $1000/month in site lease, and additional costs for electricity and backhaul. Hence installing femtocell will reduce the operating and maintaining cost, providing the good coverage capacity indoors.

5. Win-Win Model: Due to poor coverage indoor, causing interruption in services results in customer churn and hence customers look forward to different service providers. Implementing femtocell will be beneficial to providers as it offloads the data traffic from macrocell and user can get added services provided by its provider when in the coverage area of femtocell, hence creating win-win situation for both the providers and subscribers.

Challenges:

As there are many advantages and used of femtocells there have also been some technical challenges faced while deployment of femtocellls.

1. Synchronization: Femtocell synchronization is very important in accurate implementation of femtocells. In order to provide uninterrupted service to subscriber the basestation and femtocells should be very accurately synchronized.

Handsets should be accurately synchronized with the frequency of basestation.

To provide reliable handover it is necessary that femtocell should be synchronized with the basestation network, otherwise the difference in frequency can cause handover failure.

Sychronization reduces the interference which can in turn increase the quality of service.

There are different ways of synchronizing the femtocell to the network, they are described in detail as follows:

1. Femtocell Synchronization from Internet: Femtocells can be synchronized by using the internet connection with network operator. The network operator’s clock servers send the timing information to the FAP via internet in the form of packets. The protocols such as precision time protocol, network time protocol and IEEE1588 is used. The operation is Master slave based model, in which master is the network operator’s clock which sends the timing details to the slave (Access points). The main issue with this type of synchronization is that the packets can get delayed depending on the traffic on the channel. As the timing information would be transmitted frequently and need to be highly precise, this may lead to increase in bandwidth consumption.

2. Femtocell synchronization via GPS: Collecting timing information from GPS receivers which can be embedded in femtocells. It is the low cost way of synchronization. The assistance data is sent from the macrocell of the adjacent cell to femtocell which helps to provide the sufficient timing information. The problem with this way of Synchronization is the attenuation factor. The attenuation will increase in case of femtocells as it resides inside the building.

3.Using Adjacent macrocell for Synchronization: The synchronization information can be obtain by the macrocell, as the femtocells have to always exchange information for handover. This could only pose problem when the coverage of macrocell is less and signal could not be reach the femtocell network.

2. Femtocell Security: Security plays a key role in femtocell management system, as whole data is carried over the Internet. The femtocell security have been classified in two types as-

1. User Privacy- As the complete transfer of subscriber information(voice and data) is carried out over internet while backhauling, the transmitted data should be protected against security breach. Some denial of service attacks that increase the burden on the system by creating dummy and fake user s can caused the authorized users to be deprived of services and coverage.

2. Fraud users: Some unauthorized users can enjoy the facility of femtocell services by hacking the femtocell and leading to customer dissatisfaction due to unusual bills. Also they can misuse the available customer information. Hence in order to avoid these scenarios following measures were taken.

Protocols such as IPSec and extensible authentication protocol were used. Security can also be provided by continuously authenticating the femtocell service users and always ensuring that femtocell area does not increase the physical coverage area.

3. Interference: The major challenge in femtocell deployment is interference due to the same use of frequency by neighboring femtocell or the macrocell of the area.

Causes of Interference in Femtocells:

1. Random deployment of femtocells: Unlike antennas the femtocells are installed randomly without any central controlling unit that will govern the deployment of femtocells in the specific area. Femtocells can be easily installed by anyone, which can cause the ad hoc installation of femtocells ultimately increasing the probability of interference between the femtocells and base station. As the Device manager will not know the frequency allotted to the basestation in which the femtocell will be deployed.

2. Reuse of Cellular spectrum: As the bandwidth of spectrum available is less, some frequencies are reused by other cell which is not adjacent to the current cell in order to increase the spectral effeciency. This is other main cause for interference.

3. Restricted Users: In order to allow the femtocell coverage to limited number of mobile devices, the other mobile devices of same providers face coverage issues in the area near to femtocells.

Types of Interference:

Femtocell to Macro cell Interference: The interference which takes place between the femtocell and its base station is called femto-macro interference. This is caused due to restriction on number of users in one femtocell. It causes interference while uplink as well as downlink of the mobile device that are not authorized to femtocell.

Femtocell-Macrocell Interference

For example consider a femtocell using frequency f1 which is the same frequency that of macrocell network. Hence this will cause interference leading to more consumption of signal power by the femtocell and hence giving better coverage to femtocell authorized devices and causing macrocell to give poor coverage poor coverage to the mobile devices not under femtocell coverage area. Hence due to interference the non femtocells authorized user will be deprived of the services provided by the service provider. The decrease in coverage area and data capacity is directly proportional to distance between the macrocell and the mobile devices, hence the devices near to edge of the cells will suffer maximum from problems such as call disconnection, no coverage etc. Also if number of mobile devices increases in that area can lead to severe coverage issues due to already existing femtocell and increase in number of user equipments which require high coverage.

Macrocell-Femtocell Interfernce

Downlink Interference: Consider the femtocell deployed in home. Any active femtocell handset at the edge of femtocell coverage area will also start receiving the signal power from macrocell which will result in overloading of macrocell and hence less signal power will be received by the macrocell handsets.

Uplink Interference: Now the macocell handset which doesnot have access to the femtocell is in the coverage area of femtocell. The handset is calling and hence receiving the full signal power. This may affect the femtocells mobile devices which are also on call and on edge of femtocell coverge area causing the call dropping.

Femtocell-Femtocell Interference: Due to increase in number of femtocells and its deployment in random fashion can cause two neighboring femtocells to interfere with each other. The femtocell which has maximum signal power reception cannot act as the only femtocell in the area due to limited user access.

Femtocell Femtocell Interference

Mitigation of Interference:

Adaptive power control: In this mitigation way the femtocells have added feature in which they continuously monitor the received signal power from the macrocell and compares it against the total power spectral density of the macro and femto cell downlink channel. If the power received is much higher compared to that received by macro cell handsets then it automatically lower down the signal power consumption.

Intelligent Carrier Frequency Allocation: Avoid the use of same frequency within the area of adjacent cells. The better way to use this is spectrum division. The spectrum is divided and classified based on the frequencies that will be used by femocell and the other that would be used by macrocell in particular area in order to avoid the interference between the cells and femtocells. As shown in figure the spectrum is divided into free available frequency bands and that used for femtocells and also includes frequency spectra for macrocell. Also frequency convergence server use some frequency reuse algorithm in order to avoid the allocation of same frequency in nearby cells.

Mobile Phone Uplink Power Limits: When the macrocell handset makes a call in femtocell coverage the signal transmitted from the handset is sensed continuosly, if the transmitted signal strength exceeds the threshold value the handset is assigned to macrocell network hence avoiding the interference of femtocell and macrocell handsets.

Fixed Spectrum Allocation for femtocells

4. Handover: Handover is the process of transferring the control of mobile device when it moves from one cell coverage to other seamlessly. Here when the mobile device moves from femtocell to macrocell or between two femtocell, the provider needs to provide uninterrupted services to the mobile device. This mechanisim of successful transferring control of mobile device is called handover. There are three types of handover explained below.

Inbound Handover

Inbound Handover: This type of handover takes place when the mobile device is moving from the external macrocell network to the femtocell coverage area. The user equipment (mobile device) continuously measures the signal strength of all the neighboring cells. Whenever the signal strength received by the device exceeds the threshold level the device gets ready for handover. It will then get authenticated by the femtocell which transfers maximum signal power to the device. The femtocell then authenticates the mobile device. The hand over is same as that of handover between two macrocell except the signaling connection between the two cells is through internet. Each femtocells has its unique identifier number which helps the successful handover of device to the corresponding femtocell.

The figure explains the handover procedure of inbound handover.

Outbound Handover: When the mobile device moves from femtocell to macrocell then its called outbound handover. When the transmitted signal from the femtocell handset exceeds the threshold level it is handoverd to macrocell network.

Outbound Handover

Femto-Femto Handover: when mobile device moves from one femto network to other. The signaling is carried through backhauling. The whole of handover is carried out by femtocell themselves.

Conclusions

Femtocell is very effective low power and short range device that is deployed in home for increasing the coverage area for defined number of mobile devices indoors. It allows users to enjoy services similar to wi-fi under license spectrum. They also help in reducing the overall traffic on the macrocell hence increasing the reliability and efficiency of service provider network. The femtocells are user handy devices which can be deployed easily. Femtocells system has complex architecture that differ based on the type of services that will be provided by femtocells. The SIP/IMs model and Legacy network model are the two widely use architectures in femtocells system. Femtocell Network Gateway /Femtocell convergence server bridges between the femtocell aceess points and mobile operators core network. Exponential increase in use of smart phones and hence in mobile data traffic has resulted in need development of femtocell. Though there are some technical issues in femtocell implementation various strategies have also been developed to mitigate each one of them. The research is ongoing to completely overcome the present challenges of Interference and handover.
Source: http://www.ukessays.com/essays/computer-science/3g-and-4g-cellular-technologies-computer-science-essay.php

Cloud RAN vs. Picocells: The Need for Integrative Approach in Next Generation Network Design.

21 Apr

Picocell vs. Cloud RAN

When it comes to deciding on deploying small cell base stations, one is faced with a few options. One option is based on cloud RAN architecture with remote radio heads connected through optical fiber to a central base station housing the baseband processing. A second option is that of a compact base station which includes both the radio frequency and baseband processing functions. The compact base station is connected to the core network by a number of different backhaul technologies.

The availability of low cost fiber is a gating factor in deploying cloud RAN architecture. Remote radio heads require very high capacity links to support modern air interface features such as multiple antennas for MIMO. CPRI and OBSAI interfaces run at between 3 and 6 Gbps depending on the number of supported antennas. The compact base station on the other hand requires much lower capacity for backhaul – on the order of tens to over a hundred Mbps.  Low backhaul throughput requirements should translate into lower deployment cost to the advantage of compact base stations.

Cloud-RAN - Distributed Base Station Architecture

Distributed Base Station Architecture is the Fundamental Building Block of Cloud-RAN

Compact Base Station

Compact Base Station Architecture

But cloud RAN architecture can have one significant advantage over compact base stations when it comes to performance in interference environment as is typically the case with small cell deployments. The availability of central baseband processing coupled with fast, high capacity fiber backhaul allows different LTE-Advanced features to run resulting in better overall capacity than loosely coupled compact base station architecture with distributed baseband processing. For example, it becomes practical to deploy soft-cell scheme to maximize cell-splitting gain.

Shared or soft-cell techniques allow the small cells to broadcast the same control channels and synchronization signals as the macro cell. The mobile would be able to get its control and data channels from either the macro cell or small cell or from both simultaneously. This feature is enabled in LTE Release 10 with further enhancements in Release 11. It requires tight coupling between different layers in the heterogeneous network to keep control and data channels emanating from them in sync.

Soft Cell Deployment

Soft cell deployment scenario: small cell control signalling can be from the small cell, marco cell, or both.

What does all this mean? If you are an operator, you have to carefully consider your small cell deployment strategy in a holistic manner. For example, LTE features have special requirements on backhaul. This interrelationship of requirements is more complex than it has ever been. The bifurcation of technology options should be considered in an integrative manner: silos addressing different functions of the wireless network (e.g. radio access network, core network, transmission network, etc.) can lead to detrimental incompatibility.

Source: http://frankrayal.com/2013/04/18/cloud-ran-vs-picocells-the-need-for-integrative-approach-in-next-generation-network-design/

2012: the emergence of micro networks to support the core network?

16 Sep

As far as mobile users are concerned, data is data is data. Whether they stream or download content over one technology or another isn’t important to them, their main concern is having a connection capable of delivering the service they want, wherever and whenever they want it. Operators are well aware of this and are introducing the concept of heterogeneous networks (Het Nets) to help provide ubiquitous high-bandwidth connectivity.

Het Nets combine numerous micro networks, consisting of multiple low power technologies such as picocells, microcells, distributed antenna systems (DAS) and Wireless LANs, to reinforce high-usage hotspots. The micro networks seamlessly interlink with an operator’s core cellular network – or macro network – to deliver widespread coverage alongside additional capacity where it’s really needed.

The stakes are high to provide consumers with a flawless 4G experience, with European mobile broadband revenues expected to jump from approximately €10 billion in 2011 to nearly €16 billion by 2016[i]. As a result, Het Nets will play an integral role in next-generation deployment strategies across the continent next year.

One major area of expense that mobile operators will streamline in 2012 is their dependence upon network site visits. Currently, experienced technicians must regularly visit each site to configure equipment, perform maintenance and implement repairs. This inefficient use of a technician’s time can be considerably costly, especially for large networks with numerous sites in remote and distant locations.

Operators can be warned through ‘soft alarms’ when equipment begins to fall below optimum performance, as opposed to simply being alerted when equipment fails, which is often the case. This not only allows network managers to solve minor problems before they become major issues, but to choose the best time to respond and solve multiple problems in one visit.

In addition, the ability to make remote adjustments, like altering thermostat settings, completely negates the need for visits to make simple changes to infrastructure settings. Base station efficiency can be further improved by using remote monitoring software to switch-off non-essential services when traffic is low, ensuring they only consume power as and when it’s needed.

From an infrastructure perspective, the move towards energy efficient solutions was undoubtedly one of the biggest trends of 2011. The benefits operators have seen so far not only justify their initial investment but can clearly maximise a network’s long term profitability. With global telecoms revenue expected to fall by 5 per cent by 2015, as predicted by Analysys Mason,[ii] green solutions will continue to be adopted progressively throughout 2012 to offset this.

To achieve many of their ‘green’ goals, wireless operators will be investing more in clean and reliable backup power generators, remote shelter monitoring, amplifier upgrades, shelter cooling and hybrid cooling systems, and greater network intelligence.

As an example, switching to hydrogen fuel cells for backup power from traditional energy sources, such as diesel generators or batteries, illustrates just how far operational expenditure can be trimmed through ‘green’ solutions. In addition to their inherent energy efficiency, fuel cells require considerably less maintenance than diesel generators whilst taking up roughly 50 percent less space on site – which can help to reduce leasing costs. On average, the maintenance cost of fuel cells is 77 percent lower than diesel generators and the operational cost is 37 percent lower[iii]

Source: Analysys Mason: LTE – a Potential Drive for Subscriptions Growth in Europe. Ii. Source: Analysys Mason, Western European telecoms market: trends and forecasts 2010–2015. Iii. Source: CommScope White Paper, Advanced Fuel Cell Solution for Telecommunications Networks. http://www.engineerlive.com/Oil-and-Gas-Engineer/Communications/2012%3A_the_emergence_of_micro_networks_to_support_the_core_network%3F/23876/

LTE-Advanced technologies: eICIC, CoMP and CA presented by SK-Telecom

16 Jul

SK Telecom announced today that it successfully demonstrated a core LTE-Advanced technology named ‘Enhanced Inter-Cell Interference Coordination (eICIC)’ under cooperation with Qualcomm and Nokia Siemens Networks.

eICIC is a technology that coordinates signal interference between macro and pico base stations and is rapidly gaining importance as more and more micro base stations are being built in traffic concentrated areas to accommodate explosive data traffic growth, thereby aggravating inter-cell interference.

To demonstrate the technology, SK Telecom, Nokia Siemens Networks and Qualcomm created an environment where the strength of micro base station signals being transmitted to mobile devices was weaker than that of nearby macro base signals, resulting in signal interference. Then, they applied eICIC to prove that it can actually control the interference and stabilize data communications. The companies also succeeded in showing that the technology is capable of offloading data traffic by adjusting the coverage of micro base stations based on the level of data traffic concentration in macro and micro base stations. As commercial base station equipment has been used for the demonstration, the companies are expecting to achieve early commercialization of eICIC.

With the successful demonstration of eICIC, SK Telecom gained an important edge in commercializing the next-generation telecommunications network as it now holds the record of demonstrating the three core technologies needed to usher in the era of LTE-Advanced: eICIC, Coordinated Multi-Point (CoMP) and Carrier Aggregation (CA). The company successfully demonstrated CoMP at Mobile World Congress (MWC) 2011 and CA at MWC 2012. At present, SK Telecom is the only company in the world that has succeeded in demonstrating all these three technologies.

CoMP is a technology that prevents base station interference and abrupt call disconnections in coverage boundary areas by enhancing signal strength, the lack of which leads to a significant drop in data transmission speed, and CA is a technology that provides twice or faster data rates by utilizing multiple frequency bands at the same time.

SK Telecom expects to commercialize eICIC in the second half of 2013 to control signal interference and effectively offload data in downtown areas that experience heavy data traffic so as to provide customers with a mobile data service with greater speed and stability.

The company commercialized CoMP, for the first time in the world, in January 2012, after adjusting the technology to suit the current LTE system, and plans to achieve early commercialization of CA in the second half of 2013.

Meanwhile, on June 14, a consortium between SK Telecom and the Electronics and Telecommunications Research Institute (ETRI, President Kim Heung-Nam) has been chosen by the Ministry of Knowledge Economy to carry out the Ministry-led project, aimed at developing next-generation LTE technologies.

Kang Jong-Ryeol, Head of Network Technology R&D Center of SK Telecom said, “Building on its competitive LTE technologies, SK Telecom will make redoubled efforts to develop next-generation network technologies to achieve early commercialization of LTE-Advanced by next year and secure technological leadership.”

Posted: July 13, 2012

Source: http://4g-portal.com/lte-advanced-technologies-eicic-comp-and-ca-presented-by-sk-telecom?goback=%2Egde_136744_member_134009523

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