Throughput Comparison for different wireless technologies

Merged various slides from the recent 4G Americas presentation to get a complete picture of data throughput speeds for various technologies.

3GPP Rel.11 Technology Introduction whitepaper

Another excellent summary whitepaper by R&S, embedded below:

LTE- Advanced (3GPP Rel.11) Technology Introduction from Zahid Ghadialy

Timing Accuracy and Phase Performance Requirements in LTE/LTE-A/4G

Nice quick summary videos from Chronos.



If you are interested in learning more on this topic or discussions, I would recommend joining the Phase Ready Linkedin group.

3 Band Carrier Aggregation in Release-12

So it looks like in the latest 3GPP RAN meeting finally more than 2 carriers have been proposed for Carrier Aggregation. The TDoclist has a few items on 3 carriers for CA. In some cases its been specified that there is 1 uplink component carrier (1UL CC) but in other cases its not specified and I have not looked into details. Its good to finally see more than 2 carriers being discussed.

Rohde&Schwarz have explained in one of their whitepapers about the numbering of CA bands.

Now there is a possibility that we may have 2 contiguous bands and 1 band from an Inter-band so the naming would be accordingly. There are also going to be new carrier types (NCT), Band 29 for example. See details here.

Finally, If you want to learn more about Carrier Aggregation (CA) or other LTE-Advanced features, my article from last year, here, would be useful.

New Carrier Type (NCT) in Release-12 and Band 29

One of the changes being worked on and is already available in Release-11 is the Band 29. Band 29 is a special FDD band which only has a downlink component and no uplink component. The intention is that this band is available an an SCell (Secondary cell) in CA (Carrier Aggregation). 

What this means is that if this is only available as an SCell, any UE that is pre-Rel-11 should not try to use this band. It should not read the system information, reference information, etc. In fact the System Information serves little or no purpose as in CA, the PCell will provide the necessary information for this SCell when adding it using the RRC Reconfiguration message. This gives rise to what 3GPP terms as New Carrier Type for LTE as defined here. An IEEE paper published not long back is embedded below that also describes this feature in detail. 

The main thing to note from the IEEE paper is what they have shown as the unnecessary information being removed to make the carrier lean.

China Mobile, in their Rel-12 workshop presentation, have suggested 3 different types/possibilities for the NCT for what they call as LTE-Hi (Hi = Hotspot and Indoor).

Ericsson, in their Rel-12 whitepaper mention the following with regards to NCT:

Network energy efficiency is to a large extent an implementation issue. However, specific features of the LTE technical specifications may improve energy efficiency. This is especially true for higher-power macro sites, where a substantial part of the energy consumption of the cell site is directly or indirectly caused by the power amplifier.

The energy consumption of the power amplifiers currently available is far from proportional to the power-amplifier output power. On the contrary, the power amplifier consumes a non-negligible amount of energy even at low output power, for example when only limited control signaling is being transmitted within an “empty” cell.

Minimizing the transmission activity of such “always-on” signals is essential, as it allows base stations to turn off transmission circuitry when there is no data to transmit. Eliminating unnecessary transmissions also reduces interference, leading to improved data rates at low to medium load in both homogeneous as well as heterogeneous deployments.

A new carrier type is considered for Release 12 to address these issues. Part of the design has already taken place within 3GPP, with transmission of cell-specific reference signals being removed in four out of five sub frames. Network energy consumption can be further improved by enhancements to idle-mode support.

The IEEE paper I mentioned above is as follows:

Future proofing with LTE-Advanced

Future Proofing With LTE-Advanced from Zahid Ghadialy

eMBMS Release-11 enhancements

Continuing on the eMBMS theme. In the presentation in the last post, there was introduction to the eMBMS protocols and codecs and mention about the DASH protocol. This article from the IEEE Communications magazine provides insight into the working of eMBMS and what potential it holds.

Evolved Multimedia Broadcast/Multicast Service (eMBMS) in LTE-Advanced: Overview and Rel-11 Enhancements from Zahid Ghadialy

The 'Phantom Cell' concept in LTE-B

One of the LTE-B proposals by NTT Docomo is this 'Phantom Cell' concept. A recent article from the IEEE Communications Magazine expands this further:


Phantom Cell Concept — In the current deployments, there are a number of capacity solutions for indoor environments such as WiFi, femtocells, and in-building cells using distributed antenna systems (DAS). However, there is a lack of capacity solutions for high-traffic outdoor environments that can also support good mobility and connectivity. Thus, we propose the concept of macro-assisted small cells, called the Phantom Cell, as a capacity solution that offers good mobility support while capitalizing on the existing LTE network. In the Phantom Cell concept, the C-plane/U-plane are split as shown in Fig. The C-plane of UE in small cells is provided by a macrocell in a lower frequency band, while for UE in macrocells both the C-plane and U-plane are provided by the serving macrocell in the same way as in the conventional system. On the other hand, the Uplane of UE in small cells is provided by a small cell using a higher frequency band. Hence, these macro-assisted small cells are called Phantom Cells as they are intended to transmit UE-specific signals only, and the radio resource control (RRC) connection procedures between the UE and the Phantom Cell, such as channel establishment and release, are managed by the macrocell.

The Phantom Cells are not conventional cells in the sense that they are not configured with cell specific signals and channels such as cell-ID-specific synchronization signals, cell-specific reference signals (CRS), and broadcast system information. Their visibility to the UE relies on macrocell signaling. The Phantom Cell concept comes with a range of benefits. One important benefit of macro assistance of small cells is that control signaling due to frequent handover between small cells and macrocells and among small cells can be significantly reduced, and connectivity can be maintained even when using small cells and higher frequency bands. In addition, by applying the new carrier type (NCT) that contains no or reduced legacy cell-specific signals, the Phantom Cell is able to provide further benefits such as efficient energy savings, lower interference and hence higher spectral efficiency, and reduction in cellplanning effort for dense small cell deployments.

To establish a network architecture that supports the C/U-plane split, and interworking between the macrocell and Phantom Cell is required. A straightforward solution to achieve this is to support Phantom Cells by using remote radio heads (RRHs) belonging to a single macro eNB. This approach can be referred to as intra-eNB carrier aggregation (CA) using RRHs. However, such a tight CA-based architecture has some drawbacks as it requires single-node operation with low-latency connections (e.g., optical fibers) between the macro and Phantom Cells. Therefore, more flexible network architectures should be investigated to allow for relaxed backhaul requirements between macro and Phantom Cells and to support a distributed node deployment with separated network nodes for each (i.e., inter-eNB CA).

LTE-A: Downlink Transmission Mode 9 (TM-9)

When LTE was introduced in Release-8 it had 7 transmission modes that were increased to 8 in Release-9. Earlier, I posted an R&S whitepaper on the different Transmission modes (10K+ views already) that listed transmission modes till TM 8. In Release-10 (LTE-A) 3GPP Introduced a new transmission mode, TM 9. TM9 is designed to help reduce interference between base stations to maximise signal stability and boost performance. The new TM-9 enables the enhancement of network capabilities and performance with minimum addition of overhead. TM9 is designed to combine the advantages of high spectrum efficiency (using higher order MIMO) and cell-edge data rates, coverage and interference management (using beamforming). Flexible and dynamic switching between single-user MIMO (SU-MIMO) and an enhanced version of multi-user MIMO (MU-MIMO) is also provided.

A new Downlink Control Information (DCI) format - known as format 2C - is used for TM9 data scheduling. Two new reference signals are defined in TM9: Channel State Information Reference Signal (CSI-RS) and Demodulation Reference Signal (DMRS). The first is used from the UE to calculate and report the CSI feedback (CQI/PMI/RI), while the latter is an evolution - providing support for more layers - of the UE specific reference signal that is already used for beamforming in Rel-9, and is used for signal demodulation. TM-9 is particularly smart as it can detect when a mobile device is being used and send a different type of signal that is optimal for a mobile device (variable DM-RS – demodulation reference signals). This maximises the efficient use of the base station and guarantee’s a decent data rate for users.

Early results in SK Telecom press release are positive with a claimed 10-15% increase in data rates in locations where there was known inter-cell interference.

I also looked into couple of books and here is one explanation from An Introduction to LTE by Chris Cox.

To use eight layer spatial multiplexing, the base station starts by configuring the mobile into a new transmission mode, mode 9. This supports both single user and multiple user MIMO, so the base station can quickly switch between the two techniques without the need to change transmission mode.

The base station schedules the mobile using a new DCI format, 2C. In the scheduling command, it specifies the number of layers that it will use for the data transmission, between one and eight. It does not have to specify the precoding matrix, because that is transparent to the mobile. The base station then transmits the PDSCH on antenna ports 7 to 7 + n, where n is the number of layers that the mobile is using. The maximum number of codewords is two, the same as in Release 8.

The mobile still has to feed back a precoding matrix indicator, which signals the discrepancy between the precoding that the base station is transparently providing and the precoding that the mobile would ideally like to use. Instead of using the PMI, however, the mobile feeds back two indices, i1 and i2. Both of these can vary from 0 to 15, which provides more finely-grained feedback than the PMI did and in turn improves the performance of the multiple user MIMO technique. The base station can then use these indices to reconstruct the requested precoding matrix.

Embedded below is an extract from Google books for Lte-Advanced Air Interface Technology By Xincheng Zhang, Xiaojin Zhou

LTE-B, LTE-C, ... , LTE-X

Please make sure to read the comment from Kevin Flynn of 3GPP at the end

When I saw this picture above, I started wondering what LTE-B, etc. and started digging a bit deep. Came across this Ericsson presentation (embedded below) that shows the breakdown.

To just be sure that this is not Ericsson specific term, I also found a presentation by NTT Docomo (embedded below)

So I guess using LTE-B, LTE-C, etc. is better than saying 4.1G, 4.2G, etc. as we did in case of 3G/HSPA.


The presentations from Ericsson and NTT Docomo embedded below, available to download from Slideshare.

LTE evolution: Beyond lte-advanced from Zahid Ghadialy

Future Radio Access, M2M and Grand Societal Challenges from Zahid Ghadialy

Rel-11/12 3GPP Security Update

Here is the latest Security Update from 3GPP, presented in the 8th ETSI Security Workshop Jan 16-17 2013.

3GPP Security Update - Jan. 2013 from Zahid Ghadialy

All presentations are available from here to download.

Related blog posts:

• Quick update on 3GPP Release-12 progress
• The four C's of Release-12 enhancements
• Quick update on LTE Release 11 Work and Study Items
• 3GPP LTE Security Aspects
• Evolution of 3GPP Security
• 2 Presentations on Mobile technology Security

By the way, I will also be present in the Network Security conference in London in May 2013

The four C's of Release-12 enhancements

Mid last year, I did a post on the LTE Rel-12 workshop and later another post on the progress.  Late last year, 3GPP posted a news item that the Rel-12 will be available by June 2014 and the main areas of focus will be as follows:

Exploiting new business opportunities

• Public Safety and Critical Communications 
  — Group Communications (GCSE_LTE)
• Proximity Services, including both Public Safety and Commercial aspects (ProSe)
• Machine Type Communications 
  — UE Power Consumption, Small Data and Device Triggering (MTCe_UEPCOP, MTCe_SDDTE )

WiFi integration

• Network Selection aspects (WLAN_NS)
• S2a Mobility with GTP for WLAN (FS_SaMOG)
• Optimized Offloading to WLAN in 3GPP-RAT mobility (FS_WORM)

System capacity and stability

• User plane congestion (UPCON)
• Core Network Overload (FS_CNO)

In addition to those three areas, other features can still be considered for completion in the Release 12 timeframe. The SA2 Working Group - responsible for Architecture - will produce time budgets to see whether further priority could be put on;

• Pure IMS features that can run in parallel with key items
• Policy and Charging Control for supporting fixed broadband access networks, PCC for fixed terminals (P4C BB1 and BB2)
• Application Based Charging (FS_ABC)
• User Monitoring Control Enhancements (FS_UMONC)
• LIPA Mobility and SIPTO at the Local Network (LIMONET)
• Operator Policies for IP Interface Selection (OPIIS)

Working Group SA2 will provide time budgeting information, for the selected features, at the next Plenary meeting - TSG#59, in March 2013.

Nokia Siemens Networks (NSN) has published their own whitepaper on 'LTE Release 12 and Beyond' (available on Slideshare here).

The following is their take on the four C's:


Release 12 enhancements focus on the four areas of Capacity, Coverage, Coordination (between cells), and Cost. Improvements in these areas are based on using several technology enablers: small cell enhancements, macro cell enhancements, New Carrier Type (NCT) and Machine-Type Communications (MTC). These enablers are described in this paper.

Customer experience, capacity and coverage will be improved with small cell enhancements, based on inter-site Carrier Aggregation, LTE-WLAN integration and macro cell enhancements. Small cell enhancements are also known as enhanced local access.

NCT helps achieve the required changes in the physical layer and initially provides base station energy savings, flexibility in deployment and ways to reduce interference in heterogeneous networks (HetNets).

Improvements in capacity and a more robust network performance are achieved by 3D Beamforming/MIMO (Multiple Input Multiple Output), advanced user equipment (UE) receivers and evolved Coordinated Multipoint (CoMP) techniques, as well as through Self-Organizing Networks for small cell deployments.

Finally, new spectrum footprint and new business will be opened up by optimizing the system for Machine-Type Communications, as well as by, for example, using LTE for public safety.


The whitepaper is available on Slideshare here.

Quick update on 3GPP Release-12 progress

Some months back, I blogged about the 3GPP Rel-12 workshop, since then there has been progress on the Rel-12 features. Here is a quick update from 3GPP:

Future 3GPP RAN standardization activities for LTE from Zahid Ghadialy

You can download the PPT from Slideshare.

Other related posts:

• Quick Introduction to LTE-Advanced

Quick Introduction to LTE-Advanced

An article written by me for the Mobile Europe magazine where I try and explain LTE-A without going in technical details. This also includes the state of market on who is doing what.

LTE, LTE-A and 4G from eXplanoTech

Extended Access Barring (EAB) in Release 11 to avoid MTC overload

M2M is going to be big. With the promise of 50 Billion devices by 2020, the networks are already worried about the overloading due to signalling by millions of devices occurring at any given time. To counter this, they have been working on avoiding overloading of the network for quite some time as blogged about here.

The feature to avoid this overload is known as Extended Access Barring (EAB). For E-UTRAN, in Rel-10, a partial solution was implemented and a much better solution has been implemented in Rel-11. For GERAN a solution was implemented in Rel-10. The following presentation gives a high level overview of EAB for E-UTRAN and GERAN.

3GPP Enhancements for Machine Type Communications Overview from Zahid Ghadialy

In Rel-11, a new System Information Block (SIB 14) has been added that is used specifically for EAB. Whereas in Rel-10, the UE would still send the RRCConnectionRequest, in Rel-11, the UE does not even need to do that, thereby congesting the Random Access messages.

The following is from RRC 36.331 (2012-09)
***

–                SystemInformationBlockType14

The IE SystemInformationBlockType14 contains the EAB parameters.

SystemInformationBlockType14 information element

-- ASN1START

SystemInformationBlockType14-r11 ::= SEQUENCE {

    eab-Param-r11                        CHOICE {

       eab-Common-r11                       EAB-Config-r11,

       eab-PerPLMN-List-r11                 SEQUENCE (SIZE (1..6)) OF EAB-ConfigPLMN-r11

    }                                                  OPTIONAL, -- Need OR

    lateNonCriticalExtension             OCTET STRING          OPTIONAL, -- Need OP

    ...

}

EAB-ConfigPLMN-r11 ::=               SEQUENCE {

    eab-Config-r11                   EAB-Config-r11            OPTIONAL -- Need OR

}

EAB-Config-r11 ::=               SEQUENCE {

    eab-Category-r11                 ENUMERATED {a, b, c, spare},

    eab-BarringBitmap-r11            BIT STRING (SIZE (10))

}

-- ASN1STOP

SystemInformationBlockType14 field descriptions
eab-BarringBitmap Extended access class barring for AC 0-9. The first/ leftmost bit is for AC 0, the second bit is for AC 1, and so on.
eab-Category Indicates the category of UEs for which EAB applies. Value a corresponds to all UEs, value b corresponds to the UEs that are neither in their HPLMN nor in a PLMN that is equivalent to it, and value c corresponds to the UEs that are neither in the PLMN listed as most preferred PLMN of the country where the UEs are roaming in the operator-defined PLMN selector list on the USIM, nor in their HPLMN nor in a PLMN that is equivalent to their HPLMN, see TS 22.011 [10].
eab-Common The EAB parameters applicable for all PLMN(s).
eab-PerPLMN-List The EAB parameters per PLMN, listed in the same order as the PLMN(s) occur in plmn-IdentityList in SystemInformationBlockType1.

***

Here is my attempt to explain the difference in overload control mechanism in Rel-8, Rel-10 and Rel-11. Please note that not actual message names are used.

As usual, happy to receive feedback, comments, suggestions, etc.

3D-Beamforming and 3D-MIMO

When I did the summary from Rel-12 workshop, one of the feature proposed by many companies was the feature on 3D MIMO/Beamforming. Here is a quick introduction from different presentations.

A presentation by China mobile lists the motivations and Challenges is embedded below:

LTE Evolution — Rel-12 and Beyond from Zahid Ghadialy

LTE-Advanced: An Operator Perspective

"No-Edge Networks" and Multi-Stream Aggregation (MSA)

The following is from Huawei press release:


The LTE-Advanced Multi-Stream Aggregation (MSA) technology standard is capable of increasing data rates at the cell's edge. A key component of Huawei's "No-Edge Networks" concept, MSA technology coordinates macro cells to improve user data rates at the cell's edge and also between heterogeneous networking scenarios to improve peak rates and simplify mobile management to ensure a consistent user experience.

With the development of mobile broadband, operators are mostly concerned about user experience. With mobile coverage, should able to enjoy the same quality of services no matter where they are. However, with mobile communication systems, the most challenging issue is system performance at the cell's edge.

The concept behind Huawei's MSA technology is that the user is always able to receive downlink data and aggregate downlink data streams from a cell or cell group with the best signal quality. A similar method applies to uplink data, where the user always transmits uplink data to a cell or cell group with the best signal quality. The uplink data streams are aggregated on the network side.

Huawei's MSA technology reduces the number of handovers, lowering device power transmission and increasing device standby time. These advantages are in accordance with the concept of delivering a "borderless network" and "green" wireless communications. It's expected that MSA technology will improve system performance at the cell's edge by almost 30%.

MSA technology is especially suitable for macro-micro HetNets. In hotspot area, macro cells provide basic LTE coverage while the micro cells provides capacity enhancement. The use of MSA technology allows users to receive controlled signaling from macro cells and services from best quality HetNet cell. Users at any location within the network can then enjoy fast and stable data services with ultra broadband, zero waiting and ubiquitous connectivity. MSA technology brings users high speeds and high quality as well as a simple service experience.

The advanced MSA technology proposed by Huawei is set to become a key feature of the evolution to 3GPP LTE-Advanced standards. Huawei has contributed 293 core standards to the 3GPP LTE/LTE-Advanced standardization process, 20% of the global total and the most of any other company.

I wasnt able to find much information but there is this couple of slides that were submitted in Rel-12 workshop that is embedded below:

Views on Rel-12 and onwards for LTE and UMTS from Zahid Ghadialy

What do you think of this feature?

New Carrier-Aggregation Proposed Bands

Carrier Aggregation (CA) the promised feature of LTE-A that will make it compatible to IMT-A is not fully exploited in Rel-10. There are only 2 bands supported for CA in Rel-10 and the same for Rel-11. The following are the bands for Rel-10

And the following for Rel-11

Unfortunately these are not enough for all the operators launching LTE/LTE-A. As a result there is currently a study on lots of other bands ongoing within 3GPP. Here is my understanding of the bands that would be needed and the region where they would be needed. Interested in knowing if there are other operators/regions where other bands need to be included.
 

LTE, LTE-A and Testing

Some months back R&S held a technical forum where there were many interesting talks and presentations. They have now uploaded video of all these presentations that can be viewed on their website (no embedding allowed).

Available to be viewed here.