Monthly Archives: November 2012

3GPP LTE CS Fallback (CSFB )

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This tutorial describe details of LTE CSBF : Circuit Switch Fall Back, which is essential for early adaptation of LTE network.

LTE was made for packet based services. But a majority part of today’s traffic originates from CS based services like Voice and SMS. Therefore 3GPP agreed to include an intermediate solution for CS (Circuit Switch) based services until IP-based services like VoLTE completely developed and deployed. Using CSFB (CS Fallback) UE can switch to GERAN, UTRAN or CDMA2000 systems for voice services. CS fall back services are available in those areas where EUTRA systems overlap with GERAN, UTRAN or CDMA2000.

LTE CS Fallback Architecture

For CS Fallback Gs interface between MSC server and MME is required. ia SGs interface, the UE executes combined EPC and IMSI attachment and detachment procedure. Also for MT CS fallback service, CS paging is delivered via SGs interface to MME and ultimately to the UE. The SGs interface is based on the Gs interface.

LTE CS Fallback Architecture

Though CS Fallback is a temporary solution till IMS based VoLTE is completely developed and deployed, but still CS Fallback is important for enabling an easy transition to 4G LTE

There are various solutions suggested for CS Fallback staring from Cell Change Order to target system, RRC Connections Release with redirection and RRC Connection release without redirection.

Listed here are various solutions suggested in different release

LTE CS fallback options in Release 8 and 9

  • Target system Solutions Release UTRAN RRC Connection Release with Redirection without Sys Info Release 8
  • RRC Connection Release with Redirection with Sys Info Release 9
  • PS handover with DRB(s) Release 8
  • GSM RRC Connection Release with Redirection without Sys Info Release 8
  • RRC Connection Release with Redirection with Sys Info Release 9
  • Cell change order without NACC Release 8
  • Cell change order with NACC Release 8
  • PS handover Release 8
  • cdma2000 (1xRTT) RRC Connection Release with Redirection Release 8
  • enhanced 1xCSFB Release 9
  • enhanced 1xCSFB with concurrent HRPD handover Release 9
  • dual receiver 1xCSFB (RRC Connection Release without Release 9 Redirection)

CS Fallback to UMTS

CS Fallback to UMTS is quite often done with RRC Connection Release with redirection info. In this case RRC Connection release message contains the target UTRAN frequency information. Then the UE moves to the target RAT and searches for an acceptable cell by utilizing the frequency information within the RRC Connection Release. Once target cell is located it starts from IDLE and obtains required system information blocks to access the cell. This solution was recommended in 3GPP Release 8.

CS Fallback to GSM

Like CS fallback to UMTS, RRC Connection Release with redirection information is the least-effort solution for CS fallback to GSM. In this solution, the UE RRC Connection in the LTE system is released and the UE is redirected to the GSM system to set up the CS service like CS fallback to UMTS. In this redirection information, the eNodeB can indicate a target frequency. Then the UE moves to the target RAT and searches for a suitable cell by using the frequency information in the RRC Connection Release. Once the UE finds a suitable cell, it starts from IDLE and acquires the necessary system information blocks to access the cell.

I have written another analysis on LTE Circuit Switched Fallback (CSFB) Performance which provides complete picture of CSFB real world results.

Voice Over LTE – VoLTE is Battery Killer

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Voice Over LTE – VoLTE is the technology which will drive the future of voice call over next generation mobile networks and it will replace legacy circuit switched call technology. But recent studies made by Metrico Wireless give some scary results for mass implementation of VoLTE. The worst part is that VoLTE calls consumes more than twice battery power than traditional CS calls.

Every year smartphone battery is getting bigger and bigger. Some of the latest smartphones have the most powerful battery compared to last generation smartphones and it’s increasing at a rate of 14% per year. But still these larger batteries are not enough. The average device now has a dual-core processor, as many as five radios, a high-resolution display, one or more HD cameras, and multi-tasking apps, providing sophisticated new functions for subscribers—while increasing battery drain.

Metrico Wireless conducted studies in two different US cities comparing power consumption due to VoLTE on LTE network and they compared the results with same carrier’s CDMA network. Though Metrico Wireless did not mention the name of the operator, it is easy to guess as there is only one operator supports VoLTE in US.

MetroPCS is the only U.S. operator with a live VoLTE service and a commercially available handset. The 1540 milliamp hour (mAh)-battery on Metro’s sole VoLTE handset, the LG Connect 4G, also lines up with the battery capacity of the device Spirent tested.

The test was conducted for 10 minutes and average power consumption od 10 minute CS call over CDMA was 680 milliwatts (mW) and in the same time 10 minutes VoLTE call over LTE network consumed 1358 mW. Spirent estimated that on a full charge, its test smartphone could support 502.6 minutes of talk time using CDMA only, but the same charge would only deliver 251.8 minutes of talk time using VoIP on the 4G network. And that’s with all other data communications turned off.

Volte Battery Test (LTE vs CDMA)

If this proves to be typical for VoLTE handsets, it will be a big problem. The battery life of the first generation of LTE smartphones was atrocious, and handset vendors have tried to address the problem by slapping fat 3000+ mAh power cells onto their phones. Some carriers are already reluctant to embrace VoLTE since they can still squeeze plenty of life out of their 2G and 3G voice services. If VoLTE proves to be a battery killer, they will be even less inclined to move mobile voice into the IP age.

There are some good news about VoLTE though. Metrico Wireless found that for Multi-RAB scenarios when both Data and VoLTE are active at the same time, LTE performed better than CDMA but with a small margin.

VoLTE Battery Performance MultiRAB

The conclusion is that a lot need to be improved in VoLTE in terms of power consumption.

Nokia Wins Patent Lawsuit Against RIM, Wants Sales Ban

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Nokia RIM Lawsuit WiFi

Wireless industry is in war mood these days. Almost all companies fighting patent lawsuits against other. This week Ericsson sued Samsung over number of wireless patent disputes. But the big news is Nokia won patent lawsuits against the Blackberry makers. Now Nokia wants sales ban on number of Blackberry phones which use it’s WiFi patents.

Nokia said in a statement that a Swedish tribunal “found that RIM was in breach of contract and is not entitled to manufacture or sell WLAN products” without first agreeing to royalty terms with Nokia. As a result, Nokia said it is seeking court action to block the sale of RIM devices with Wi-Fi capabilities in the United States, the UK and Canada. (Wireless local access network technology, or WLAN, is usually marketed as Wi-Fi.)

RIM is not doing so good these days and it’s market share are not promising. Analysts have warned of dire consequences for RIM: “This could have a significant financial impact to RIM, as all BlackBerry devices support WLAN,” IDC analyst Francisco Jeronimo told Reuters.

Canalys analyst Pete Cunningham added: “If a sales ban was imposed it would be a massive blow for RIM as it manages its transition to the new BlackBerry 10 software platform.”

Nokia said more than 40 companies license its handset patents, but RIM had argued that an earlier licensing deal with Nokia meant it should not have to pay a separate fee for Wi-Fi technology.

Peter Misek, an analyst at the New York-based investment bank Jefferies, said Nokia’s filings mean that RIM likely will end up paying royalties of $2 to $5 per phone, according to Newser.

Verizon LTE Map – 4G Coverage

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Verizon lte coverage map suggests that Verizon is the largest LTE network in USA with 4G coverage in most part of United States. Providing LTE over 440 cities Verizon LTE network provide more LTE coverage then all other network combined. 80% of American population can access to Verizon’s 4G LTE network.

Verizon 4G LTE Coverage Map

Verizon 4G LTE MAP

Here are some facts about Verizon 4G LTE Network

The performance and capabilities of 4G LTE will be unmatched in the marketplace, allowing customers to do things never before possible in a wireless environment. Consider some of the advantages that Verizon Wireless’ implementation of 4G LTE will provide:

HIGHER DATA RATES:

With Verizon Wireless’ 10 + 10 MHz implementation, LTE will be supporting average data rates per user of 5-12 Mbps in the forward link, and 2-5 Mbps in the reverse link. Both maximum and average LTE data rates are significantly higher in the reverse and forward links than those supported by existing 3G networks. LTE will enable video application on the downlink as well as uplink – including, but not limited to video-sharing, surveillance, conferencing and streaming in higher definition than is possible with existing 3G technology today.

BETTER MULTIPATH, MOBILITY AND POWER PERFORMANCE:

The advanced radio characteristics of LTE address several issues that have traditionally crippled cellular wireless, including multipath and multiuser interference. LTE’s use of Orthogonal Frequency-Division Multiple Access (OFDMA) and multiple-input and multiple-output (MIMO) in the downlink transmission effectively eliminates intra-cell multiuser interference and minimizes inter-cell multiuser interference thereby maximizing performance. Similarly, the single carrier frequency-division multiple access (SC-FDMA) uplink transmission allows for user equipment to transmit low power signals without the need for expensive power amplifiers. Improvement in battery power consumption in end-user devices (UEs) is a side-benefit of the coverage and multipath/power performance advantages offered by LTE.

LATENCY:

The user plane latency achieved in LTE is approximately one-fourth the corresponding latency in existing 3G technologies, providing a direct service advantage for highly immersive and interactive application environments, such as multiplayer gaming and rich multimedia communications.

SIMULTANEOUS USER SUPPORT:

LTE provides the ability to perform two-dimensional resource scheduling (in time and frequency), allowing support of multiple users in a time slot, resulting in a much better always-on experience while enabling the proliferation of embedded wireless applications/systems. In contrast, existing 3G technology performs one-dimensional scheduling, which limits service to one user for each timeslot.

SECURITY:

LTE provides enhanced security through the implementation of Universal Integrated Circuit Card (UICC) Subscriber Identity Module (SIM) and the associated robust and non-invasive key storage and symmetric key authentication using 128-bit private keys. LTE additionally incorporates strong mutual authentication, user identity confidentiality, integrity protection of all signaling messages between UE and Mobility Management Entity (MME) and optional multi-level bearer data encryption.

SIMPLIFIED WORLDWIDE ROAMING:

Verizon Wireless’ chosen migration path to LTE, the widely adopted next-generation 3GPP standard, will provide the greatest opportunities for seamless international roaming.

MASS DEPLOYMENT:

LTE’s inherent support for Internet Protocol version 6 (IPV6) addressing and International Mobile Subscriber Identity (IMSI)-based identifiers makes mass deployments of machine-to-machine applications over LTE possible.

5G Technology – Next Generation Wireless Access Technology

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What is 5G technology? Does it really exists? What we are going to expect from 5G Mobile Technology?

At the moment when 4G LTE deployment going on on full swing around the world, the search of next generation mobile technology is already begun. 5G Cell Phone Technology which is still not a standard term in ITU or 3GPP is expected to arrive in year 2020, which will mark completion of 10 years of 4G LTE technology. Starting from 1st generation of mobile technology, a new mobile generation has appeared every 10th year. 1G system (NMT) was introduced in 1981, while 2G systems (GSM) started rolling out in 1992. Similarly 3G started in 2001 and 4G LTE systems in 2011, with active deployment continues in 2012.

Future of wireless communication

The development of the 2G (GSM) and 3G (IMT-2000 and UMTS) standards took about 10 years from the official start of the R&D projects, and development of 4G systems started in 2001 or 2002.

The official 5G Technology R&D project started today (27th November 2012) in the form of METIS project (Mobile and wireless communications Enablers for the Twenty-twenty Information Society).

What is METIS Project?

METIS, Mobile and wireless communications Enablers for the Twenty-twenty (2020) Information Society, is a large EU co-funded research project starting in November 2012. The project objective is to respond to societal challenges for the year 2020 and beyond by laying the foundation for the next generation of the mobile and wireless communications system. METIS is a consortium of 29 partners spanning telecommunications manufacturers, network operators, the automotive industry and academia.

What METIS Project will do?

The project will have to respond to the increase in traffic volume, by increasing capacity and by improving efficiency in energy, cost and spectrum utilization.

  • METIS project will lay the foundation for the future “5G” mobile and wireless communications system. This is the first step towards 5G Technology
  • METIS will develop a system concept that delivers the necessary efficiency, versatility and scalability. The project will investigate key technology components supporting the system, and will also evaluate and demonstrate key functionality.
  • The R&D team will provide a proof-of-concept by means of simulations and test-beds. In particular, METIS will demonstrate through hardware test-beds key technology components developed in the project.

METIS is co-funded by the European Commission and the project will receive from the EU nearly €16 million of its €27 million budget.

METIS Project On Web

What is expected from 5G Technology?

Pervasive networks providing ubiquitous computing

Mobile users can simultaneously be connected to several mobile technologies at the same time and seamlessly move between them. These access technology may be 1G, 2G, 3G, 4G, 5G mobile networks or WLAN, WiFi or any other future access technologies. in 5G technology this concept may be developed further.

Group cooperative relay

Data rate is not the only way to measure efficiency of a mobile access technology, to provide higher data throughput throughout a cell area is biggest challenge. In current research, this issue is addressed by cellular repeaters and macro-diversity techniques, also known as group cooperative relay, as well as by beam division multiple access. In 5G mobile technology there should be some major improvements may happen in this area.

Dynamic Adhoc Wireless Networks

Identical to Mobile ad hoc network (MANET), Wireless mesh network (WMN) or wireless grids, combined with smart antennas, cooperative diversity and flexible modulation.

Vandermonde-subspace frequency division multiplexing

A modulation scheme to allow the co-existence of macro-cells and cognitive radio small-cells in a two-tiered LTE/4G network

Massive Dense Networks

Known as Massive Distributed MIMO providing green flexible small cells 5G Green Dense Small Cells.

LTE UE Category – Terminal Capabilities

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LTE UE category allows network to operate with terminals with different data capabilities as well as allows market to differentiate between low end devices with lower data capabilities against high-end devices with higher data rates. This differentiations determines price or UEs in many cases.

In LTE not all UEs support all categories and also terminals from an earlier release does not support features introduced in later version of 3GPP releases. For example a release 8 UE does not support features like carrier aggregation which was introduced in Release 10.

So during connection setup, UE needs to indicate network about what 3GPP release it supports as well as the capabilities it support withing the specific release.

3GPP release 8/9 UE can have 5 different categories, Category 1 support minimum set of functionality while category 5 UE has maximum data rate and supports full set of features. In release 10 features such as carrier aggregation and uplink spatial multiplexing are added. So from release 10 three new UE categories are added. and the maximum number of component carriers and degree of spatial multiplexing supported, both in uplink and downlink, are signalled separately from the category number. A release-10 terminal may therefore declare itself as, for example, category 4 but capable of uplink spatial multiplexing. So UE categories 1-5 have different meaning in Release 10 when compared with Release 8/9.

For backward compatibility purpose Release 10 UE has to declare both Release 8/9 capabilities and Release 10 capabilities.

LTE UE Categories

UE Category12345678
Downlink peak rate
(Mbit/s)		10501001503003003003000
Uplink peak rate (Mbit/s)525505075501501500
NOTE: Category 1-5 : Release 8/9/10, Category 6-8: Release 10 only
Maximum downlink modulation: 64 QAM
Maximum uplink modulation: 16QAM (Category 1-4 and 6), 64QAM (Category 5 and 7)

LTE Handover Overview

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This tutorial describes LTE Handover types and procedures.

LTE changed the way traditional mobile network were working. Leaving circuit switched technology far behind LTE became the first All-IP mobile network. Ĺike other mobile networks LTE also have big challenges when it comes to mobility areas like handover and reselection. Handover in particular is more complicated in LTE as LTE has to deal with Intra-LTE handovers as well as handovers between LTE and UTRAN, LTE and GERAN and other mobile networks.

The basic objective of handover procedures are:

  • QoS should be maintained all the time. Not after handover but during handover as well.
  • Handover should not drain UE battery.
  • UE should able to continue it’s normal services before and after handover. For example a voice call before handover should be maintained after handover as well.
  • Seamless handoff between 2G/3G/CDMA/LTE technologies.

Normally there are two type of handover approach available in mobile networks.

  • Network Controlled: In this case network makes handover decisions.
  • Mobile Evaluated: The UE will make handover decisions and inform network about it. But still network takes the final decision based on radio resource available in target cell.

In LTE network a hybrid approach is used. UE sends measurement information to network and based on those measurements network asks UE to move to a target cell.

Types of Handover in LTE network

  • Intra-LTE Handover: In this case source and target cells are part of the same LTE network.
  • Inter-LTE Handover: Handover happens towards other LTE nodes. (Inter-MME and Inter-SGW)
  • Inter-RAT: Handover between different radio technologies. For example handover from LTE to WCDMA.

Intra-LTE Handovers

There are different use cases for Intra-LTE handovers. There are primarily three types of Intra-LTE handover can be possible

Intra-MME/SGW: Handover using X2 Interface

X2 is the interface between two eNodeBs, serving eNodeB and target eNodeB in this case. When X2 interface is present then handover is completed without EPC (Evolved Packet Core) involvement. The release of the resources at source eNodeB is triggered by target eNodeB.

Intra-MME/SGW: Handover using S1 Interface

In case when X2 interface is not available and source eNodeB and target eNodeB are part of same MME/SGW then handover is carried out through S1 interface. The S-eNB initiates the handover by sending a Handover required message over the S1-MME reference point. The EPC does not change the decisions taken by the S-eNB.

Inter-LTE Handovers

Inter-MME Handover

In Inter-MME handover two MME are involved in handover, source MME and target MME. The source MME (S-MME) is in charge of the source eNodeB and target MME (T-MME) is in charge of target eNodeB.

Inter-MME handover occurs when UE moves between two different MMEs but connected to same SGW.

Inter-MME/SGW Handover

This is same as Inter-MME but only difference is that here UE need to move from one MME/SGW to another MME/SGW. Source eNodeB is part of one MME/SGW and target eNodeB is in another MME/SGW.

Inter-RAT Handover

Handover from eUTRAN to UTRAN

In case of handover between eUTRAN to UTRAN, the source eNodeB is connected to source MME and SGW and target RNC is connected to Target SGSN and Target SGW.

First the required resources are reserved in UTRAN system and the handover is carried out.