SingTel announced has completed nationwide LTE (Long Term Evolution) coverage to support the high speed 4G mobile

SingTel announced on Tuesday that it has completed nationwide LTE (Long Term Evolution) coverage to support the high speed 4G mobile network.

In a statement to media, it said it had spent S$150 million to provide nationwide 4G coverage. LTE is the next evolution of mobile networks which is expected to offer higher speeds and lower latencies. Commonly referred as the fourth generation (4G) mobile network, the LTE network delivers theoretical download speeds of up to 75Mbps.

SingTel subscribers can now access nationwide street-level coverage of about 95 per cent. This includes indoor coverage in over 550 buildings, including shopping malls, hotels and other commercial properties but does not yet cover national parks, reservoirs and MRT tunnels.

Singtel's 3G network has also been upgraded from 21Mbps to 42Mbps. The telco added that it is the first to offer dual-band street-level coverage nationwide in Singapore. This dual-band capability doubles the data-handling capacity of the network, and helps relieve the strain during peak periods for multimedia applications such as video and music streaming, web surfing, file downloads and online games.

The telco is also the first in the country to deploy Multiple-Input-Multiple-Output (MIMO) technology in commercial buildings to boost maximum user download speeds from 75Mbps to 150 Mbps. This has already been installed in shopping malls including Nex, Jurong Point, Tampines Mall and Changi Airport. 

But customers are unlikely to be able to fully leverage the faster LTE network until the introduction of the next generation of 4G LTE devices which is being rolled out from the second half of the year.

M1 was the first telco to announce nationwide coverage for its LTE network last year. Starhub is scheduled to complete nationwide LTE coverage for its network by the end of 2013.

source: http://news.yahoo.com/singtel-completes-nationwide-lte-coverage-134528477.html

ALTERNATIVES TO 4G LTE

ALTERNATIVES TO 4G LTE

Recently, lower frequencies are given much imortance because they can travel a signal farthest. But this was due to the technology limits not physics.atmospheric absorption is same for all signals whether it is of 50 mhz or 10 mhz.higher frequencies have shorter wavelenghts in the past that was its disadvantage.low cost antennas scaled by wavelenths so shorter wavelenths are meant for smaller antennas.secondly shorter wavelengths are reflectd easily which results in multipath propagations.

Silicon devicescare expected to be more powerful as they are able to decode multiple signals , adjust signal offset and sum them.thus disadvantage of MIMO become its advantage. WIFI will soon to be deployed with WIMAX and LTE.since there is vastly more spectrum available at 5MHZ then the sum of TV white spacing plus licensed WIMAX and cellular spectrum, WIFI capacity will increase.

Electronically steerable high-gain antennas are used in WIFI network to enhance its signal strength. These anteenas reduce interference allowing multiple independent high capacity transmission in the same area. By using affordable wifi routers supporting multiple connections of 200 to 500 mbps each over a distance of one to two kilometres, there will be interesting alternatives.

ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS (OFDMA) - SINGLE-CARRIER FDMA (SC-FDMA)

ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS

It is a multi user version of digital modulation scheme.it works by assigning subsets of subcarriers to individual users.This technique has following advantages over CDMA:

1. It can combat multipath interference and it is less complex.
2. It can achieve a higher MIMO spectral efficiency.

Principle—  because of feedback information about the channel conditions, user to subcarrier assignment can be achieved. In this different number of subcarriers can be assigned to different users in view to support Quality of service that means to control data rate and error probability for each user.This is achieved by combining OFDM with time division multiple access. In this constant and shorter delay can be achieved. It is considered to be highly suitable for broadband wireless networks due to its advantagesincluding scalability and MIMO and it ability of channel frequency selectivity.It is used in Wimax and 3GPP LTE. High speed OFDM packet acess (HSOPA) now named as Evolved umts terrestrial radio access (E-UTRA).

  SINGLE-CARRIER FDMA (SC-FDMA)

It is a frequency- division multiple access scheme. It deals with the assignment of multiple users to a shared communication resorce.  It has drawn great attention as an attractive alternative to OFDMA. It has been adopted as the uplink multiple access scheme in 3GPP LTE or E-ULTRA ( evolved ultra). The major advantage of SC-FDMA is low PAPR (peak-to-average power ratio).

Transmission of SC-FDMA is very similar to OFDMA. In this, for each user the sequence of bits transmitted is mapped in symbols (BPSK,QPSK).

In SC-FDMA multiple access among users is made possible by assigning different users different set of sub carriers. The distinguishing feature  of SC-FDMA is that it leads to single carrier transmit signal in contrast to OFDMA which is multi carrier transmission scheme.

Advantages:

Low PAPR, low sensitivity to carrier frequency offset, greater robustness against spectra nulls, less sensitive to non linear distortion and hence, it allows the use of low cost power amplifiers.