Emergency calls routing in LTE

The picture below is shown the flow used making Emergency Calls in LTE.

1. The emergency called from user is prioritized.
2. Registration of IMS emergency.
3. detect of emergency.
4. The UE location is inquired.
5. User plane is established for voice.
6. Gets information on the precise user location.

LTE vs WiMAX

LTE and WiMAX continues to rage at least three years after it ignited. Late in 2007, Verizon and AT&T said they would adopt LTE, viewed as a competing technology to mobile WiMAX, as the underpinning of their 4G networks. Both carriers said LTE provides a more natural upgrade for their GSM/UMTS/HSPA/CDMA-based networks and subscribers.

Though many, except for Sprint and Clearwire, think it might already be over, with LTE the winner. Sprint and Clearwire turned up service in Baltimore in late 2008. As of May 2010, Clearwire has commercial WiMAX services available in 27 U.S. markets, covering more than 34 million points of presence. Clearwire is offering the service on a wholesale basis to Sprint, Comcast and Time Warner Cable. By the end of 2010, Clearwire will have built out a WiMAX network that spans all major U.S. markets and covers 120 million points of presences. 

Both wireless technologies are intended to offer ubiquitous broadband at multiple megabits per second. Mobile WiMAX is an IEEE specification also known as 802.16e and designed to support as high as 12Mbps data-transmission speeds. It uses Orthogonal Frequency Division Multiple Access, which transmits data by splitting radio signals that are broadcast simultaneously over different frequencies. These signals are immune to interference and can support high data rates.

LTE was developed in the 3G Partnership Project as the natural progression of High-Speed Packet Access (HSPA), the GSM technology that is currently used by carriers such as AT&T to deliver 3G mobile broadband. LTE is a modulation technique that is designed to deliver 100Mbps per channel and give individual users performance comparable to today's wired broadband. 

LTE technology in Malaysia (news)

In year 2010
According to the news in year 2010, the Malaysian government is expected to release 9 blocks of spectrum for 4G Long Term Evolution (LTE) to 9 players soon.

There will be,

• 4 Mobile telcos - Celcom, DiGi, Maxis & U-mobile 
• 4 WiMAX operators - AMAX, P1, REDtone & YTL
• A new comer

The 9 companies have been informed via fax that they have been allocated the 2.6GHz spectrum for 4G LTE use. This will only take effect on 1st January 2013 which is a long way to go, and time is something that the players need to roll out commercially. Each of them will be getting 20MHz block of the spectrum.

2 years (2010 - 2012) should give the players sufficient head start to evaluate vendors, conduct trials and plan out their coverage expansion. By 2013, we should have more 4G LTE devices in the market.

In year 2011

According to the news in year 2011, Malaysia is ready to move its mobile broadband to the next generation platform by adopting the third-generation (3G) long-term evolution (LTE) technology anytime in the near future.

Leslie Shannon (Senior Market Consultant Nokia Siemens Network) said Malaysian telecommunication carriers have experienced a high mobile broadband usage demand among their customer base, thus, adopting the LTE should not be a problem.

She also added that carriers are looking towards the next generation that would have far greater bandwidth and, the LTE offers that promise. Other than that, local telecommunication companies are very smart in fixing the pricing and marketing being right.

She also said that Malaysia, after the Malaysian Communications and Multimedia Commission grants licenses to telco companies to kick start the LTE technology, will join the group of nations which are already feeling its success, such as the United States, Finland and Uzbekistan.

The LTE, as the most efficient mobile broadband technology, provides excellent user experience. This is through an extremely fast broadband experience and is defined for more frequency bands than any other.

It can be used on paired and unpaired spectrum allocations making it a truly global standard.

In year 2012

Since December 2011, DiGi has begun a network upgrade of epic proportions. 
 

The upgrade is expected to continue through 2012 and within this period DiGi targets to upgrade over 400 sites a month on average. Once completed, a total of over 5,000 DiGi sites will have been upgraded. 

DiGi says its “Tomorrow Network” will be Malaysia’s first LTE-equipped network by the end of 2012. At the same time the upgraded network will also expand existing EDGE and 3G coverage to 95.8% of the Malaysian population. In addition, DiGi also promises a more stable and environmentally friendly network once the year round upgrade is completed.

In this respect, Yes did an amazing job with its WiMAX network covering over 60% of the populated areas in West Malaysia from day one. What Yes did is a hard act to follow but it is not impossible and we’re pretty sureDiGi is aware of this. So we’re expecting DiGi’s LTE footprint to be considerable so that it will be practical.

Pros and cons of LTE technology

Pros of LTE

1. LTE decrease the traffic of communication in term of sending data.

2. LTE is focuses on voice over internet protocol (VoIP); therefore it can support more data capacity.

3. LTE increases the mobile broadband users by allowing more users to use the same frequency.

4. LTE facilitates the current applications to perform on better speed.

5. LTE uses the solution called “Orthogonal” to separate frequencies into different channel in order to protect the disturbance of each channel.

6. LTE offers faster data rate transfer as compare to existing 3G network equipments by using radio waves over the same bandwidth.

7. LTE can support voice and SMS text messaging using existing networks via Generic Access (VoLGA).

8. LTE no need rebuilding their entire networks from the ground up to allows wireless broadband providers to transition to this new technology.

Cons of LTE 

1. New equipments will be needed to be installed. Therefore, the start-up costs of service providers and consumers for equipment upgrades are too high.

2. LTE technology need to use additional antennas at network base stations for data transmission as stated that LTE uses a SC-FDMA 1×2 configuration. As a result to the network upgrades users need to buy new cell phones to make use of new network infrastructure.

LTE network topology

In the video above, it briefly explain the function of each system in the LTE network topology. It is formed by,
- Evolved Packet Core (EPC)
- eUTRAN
- Serving GPRS support network (SGSN)
- IRAT GSM network
- UMTS network

The LTE system works

How LTE actually works?

In LTE system, it uses two different types of air interfaces (radio links), one for downlink which the signal travels from tower to device, and one for uplink which the signal travels from device to tower. In LTE, it utilizes the optimal way to do wireless connections both ways and this utilization makes a better optimized network and better battery life on LTE devices.

Figure: Verizon Cell Tower

For the downlink,                                                                                              LTE uses an orthogonal frequency division multiple access (OFDMA) air interface as opposed to the CDMA and TDMA air interfaces. OFDMA mandates that MIMO (multiple in, multiple out) is used. The stability of the connection will increases and latency will also get decrease tremendously by having MIMO that devices have multiple connections to a single cell. However, there is a significant disadvantage in MIMO that the noise caused by the antenna being so close to each other on smaller phones and this may cause LTE performance to drop. 

For the uplink,                                                                                                   LTE uses the discrete Fourier transform spread orthogonal frequency division multiple access (DFTS-OFDMA) scheme of generating a single carrier frequency division multiple access (SC-FDMA) signal. Why SC-FDMA better for uplink? This is because it has a better peak-to-average power ratio over OFDMA for uplink. LTE-enabled devices, in order to conserve battery life, typically don’t have a strong and powerful signal going back to the tower. Therefore, a lot of the benefits of normal OFDMA would be lost with a weak signal. Despite SC-FDMA is still a MIMO system and LTE uses a SC-FDMA 1×2 configuration, where the 1 there represent an antenna on the transmitting device while the 2 means there are two antennas on the base station for receiving.

Handover process in the LTE system

What is handover? 

Handover is the process enables a call to proceed without interrupted when a user moves from a cell to another. It may degrade the performance of transmission control protocol (TCP) connections and real-time applications in wireless data networks. 

Figure: Handover process in LTE network

Handover can be divided into few steps; initiation, resources reservation, execution, and completion. The process flow as following:

1. the procedure starts with the UE measurement report configured by source eNB. 
2. If certain network configured conditions are satisfied,  UE will send measurement report according to the rules set by system specifications.
3. The source eNB will then make the decision to perform handover based on the measurement report where the measurement report indicates the which needed to be handed over.
4. Then, source eNB issues a handover request message to the target eNB.
5. The handover preparation involves exchange of signalling between serving and target eNB, and admission control of the UE is performed by  target  eNB. 
6. Upon successful handover preparation, the target eNB handover request acknowledgement to the source eNB. 
7. The handover decision is made and consequently the handover command will be sent to the UE. 
8. The UE responds with a  handover confirm message, which notifies the completion of the handover procedure at the radio access network part.

Upon successful synchronization at the target eNB, this last one transmits an uplink scheduling grant to the UE. It should be noted that the signalling messages described above belong to the radio resource control (RRC) protocol.

The LTE capabilities

The capabilities of LTE include:

• The bandwidth of uplink and downlink with 20 MHz.
• The LTE is Operate in both the TDD (forward and reverse channel occupy different time slots of the same frequency band) and FDD (forward and reverse channel occupy different frequency bands) modes. 
• The scalable bandwidth up to 20 MHz where covering 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz in the study phase.
• Increased spectral efficiency over Release 6 HSPA by two to four times
• Reduced latency. (the 3.5G networks, a user can expect a 2 second or longer delay to set up the first connection, and then a 50 ms latency (one way) afterwards. LTE being all IP and having a much flatter architecture, the initial data packet connection should be much faster, up to 5 ms latency (one way) afterwards.

Comparison all generations up to LTE

The table below is about the 1G system since 1970 up to 4G technology. The table contains of the definition, speed, technology used, the time period of the current generations, and features of them.

Generation (1G - 4G)	Definition	Throughput/ Speed	Technology	Time period	Features
1G	Analog	14.4 Kbps (peak)	AMPS,NMT,TACS	1970 – 1980	Voice only allow to use in the wireless phones.
2G	Digital Narrow band circuit data	9.6/14.4 Kbps	TDMA,CDMA	1990 to 2000	2G capabilities are achieved by allowing multiple users on a single channel via multiplexing. During 2G Cellular phones are used for data also along with voice.
2.5G	Packet Data	171.2 Kbps(peak) 20-40 Kbps	GPRS	2001-2004	In 2.5G the internet becomes popular and data becomes more relevant. 2.5G Multimedia services and streaming starts to show growth. Phones start supporting web browsing though limited and very few phones have that.
3G	Digital Broadband Packet Data	3.1 Mbps (peak) 500-700 Kbps	CDMA 2000 (1xRTT, EVDO) UMTS, EDGE	2004-2005	3G has Multimedia services support along with streaming are more popular. In 3G, Universal access and portability across different device types are made possible. (Telephones, PDA’s, etc.)
3.5G	Packet Data	14.4 Mbps (peak) 1-3 Mbps	HSPA	2006 – 2010	3.5G supports higher throughput and speeds to support higher data needs of the consumers.
4G	Digital Broadband Packet All IP Very high throughput	100-300 Mbps (peak) 3-5 Mbps 100 Mbps (Wi-Fi)	WiMax LTE Wi-Fi	-	Speeds for 4G are further increased to keep up with data access demand used by various services. High definition streaming is now supported in 4G. New phones with HD capabilities surface. It gets pretty cool. In 4G, Portability is increased further. World-wide roaming is not a distant dream.

The explanation of LTE

This video briefly explain the LTE about. What it is and how it will change the communications industry world.