Pages

Join our LinkedIn group

Showing posts with label LTE-Advanced. Show all posts
Showing posts with label LTE-Advanced. Show all posts

Sunday, 19 October 2014

What is (pre-5G) 4.5G?

Before we look at what 4.5G is, lets look at what is not 4.5G. First and foremost, Carrier Aggregation is not 4.5G. Its the foundation for real 4G. I keep on showing this picture on Twitter


I am sure some people much be really bored by this picture of mine that I keep showing. LTE, rightly referred to as 3.9G or pre-4G by the South Korean and Japanese operators was the foundation of 'Real' 4G, a.k.a. LTE-Advanced. So who has been referring to LTE-A as 4.5G (and even 5G). Here you go:


So lets look at what 4.5G is.
Back in June, we published a whitepaper where we referred to 4.5G as LTE and WiFi working together. When we refer to LTE, it refers to LTE-A as well. The standards in Release-12 allow simultaneous use of LTE(-A) and WiFi with selected streams on WiFi and others on cellular.


Some people dont realise how much spectrum is available as part of 5GHz, hopefully the above picture will give an idea. This is exactly what has tempted the cellular community to come up with LTE-U (a.k.a LA-LTE, LAA)

In a recent event in London called 5G Huddle, Alcatel-Lucent presented their views on what 4.5G would mean. If you look at the slide above, it is quite a detailed view of what this intermediate step before 5G would be. Some tweets related to this discussion from 5G Huddle as follows:

Finally, in a recent GSMA event, Huawei used the term 4.5G to set out their vision and also propose a time-frame as follows:



While in Alcatel-Lucent slide, I could visualise 4.5G as our vision of LTE(-A) + WiFi + some more stuff, I am finding it difficult to visualise all the changes being proposed by Huawei. How are we going to see the peak rate of 10Gbps for example?

I have to mention that I have had companies that have told me that their vision of 5G is M2M and D2D so Huawei is is not very far from reality here.

We should keep in mind that this 4G, 4.5G and 5G are the terms we use to make the end users aware of what new cellular technology could do for them. Most of these people understand simple terms like speeds and latency. We may want to be careful what we tell them as we do not want to make things confusing, complicated and make false promises and not deliver on them. 

Saturday, 27 September 2014

Elevation Beamforming / Full-Dimension MIMO


Four major Release-13 projects have been approved now that Release-12 is coming to a conclusion. One of them is Full dimension MIMO. From the 3GPP website:

Leveraging the work on 3D channel modeling completed in Release 12, 3GPP RAN will now study the necessary changes to enable elevation beamforming and high-order MIMO systems. Beamforming and MIMO have been identified as key technologies to address the future capacity demand. But so far 3GPP specified support for these features mostly considers one-dimensional antenna arrays that exploit the azimuth dimension. So, to further improve LTE spectral efficiency it is quite natural to now study two-dimensional antenna arrays that can also exploit the vertical dimension.
Also, while the standard currently supports MIMO systems with up to 8 antenna ports, the new study will look into high-order MIMO systems with up to 64 antenna ports at the eNB, to become more relevant with the use of higher frequencies in the future.
Details of the Study Item can be found in RP-141644.
There was also an interesting post by Eiko Seidel in the 5G standards group:

The idea is to introduce carrier and UE specific tilt/beam forming with variable beam widths. Improved link budget and reduced intra- and inter-cell interference might translate into higher data rates or increased coverage at cell edge. This might go hand in hand with an extensive use of spatial multiplexing that might require enhancements to today’s MU-MIMO schemes. Furthermore in active antenna array systems (AAS) the power amplifiers become part of the antenna further improving the link budget due to the missing feeder loss. Besides a potentially simplified installation the use of many low power elements might also reduce the overall power consumption. 

At higher frequencies the antenna elements can miniaturized and their number can be increased. In LTE this might be limited to 16, 32 or 64 elements while for 5G with higher frequency bands this might allow for “massive MIMO”. 

WG: Primary RAN1 (RP-141644) 
started 06/2014 (RAN#64), completion date 06/2015 (RAN#68)
work item might follow the study with target 12/2015 (RAN#70) 

Supporting companies
Samsung/NSN, all major vendors and operators 

Based on RAN1 Rel.12 Study Item on 3D channel model (TR36.873) 

Objectives 
Phase 1: antenna configurations and evaluation scenarios Rel.12 performance evaluation with 3D channel model 

Phase 2: study and simulate FD-MIMO enhancement identify and evaluate techniques, analyze specification impact performance evaluation for 16, 32, 64 antenna elements enhancements for SU-/MU-MIMO (incl. higher dimension MU-MIMO) (keep the maximum number of layer per UE unchanged to 8)


An old presentation from Samsung is embedded below that will provide more insight into this technology:



Related post:

Sunday, 24 August 2014

New LTE-A UE Category 9 and 10 in Rel-11

Its been a while since we saw any new UE categories coming but then I noticed some new categories came earlier this year for Release-11. The latest 3TPP TS 36.306 have these new Category 9 and Category 10 as follows.
For those who are aware of the categories of the UE's being used in practice may be aware that the most common ones have been 'Category 3' with 100Mbps max in DL and 50Mbps max in UL. The new 'Cat. 4' devices are becoming more common as more manufacturers start bringing these devices to the market. They support 150Mbps max in DL and 50Mbps max in UL. Neither of them supports Carrier Aggregation.

Having said that, a lot of Cat. 4 devices that we may use in testing actually supports carrier aggregation. The next most popular devices soon to be hitting the market is Cat. 6 UE's with 300Mbps max in DL and 50Mbps max in UL. Category 6 UE's support 2 x 20MHz CA in downlink hence you can say that they can combine 2 x Cat. 4 UE's in DL but they do not support CA in uplink hence the UL part remains the same as Cat. 4 device.

Cat. 9 and 10 are interesting case as Car. 8 was already defined earlier to meet IMT-A requirement as shown below.


To meet IMT-A requirements of peak data rates of 1Gbps in UL and DL, LTE-A had to define category 8 with 5 band CA and 8x8 MIMO to be able to provide 3Gbps max in DL and 1.5Gbps max in UL. No one sees this device becoming a reality in the short term.

The new categories will have to be defined from Cat. 9 onwards.

Cat. 9 allows 3 x Cat. 4 device CA in the downlink to have the maximum possible downlink data rates of 450Mbps but there is no CA in the uplink. As a result, the UL is still 50Mbps max. Cat. 10 allows carrier aggregation in the uplink for upto 2 bands which would result in 100Mbps max in UL.

The LG space website gives a better representation of the same information above which is shown below:



A UE category 9 transmits Rel 11 category 9 + Rel 10 category 6 + Rel 8 category 4

With Release-12 due to be finalised later in the year, we may see new UE categories being defined further.

Tuesday, 18 February 2014

The Rise and Rise or '4G' - Update on Release-11 & Release-12 features

A recent GSMA report suggests that China will be a significant player in the field of 4G with upto 900 million 4G users by 2020. This is not surprising as the largest operator, China Mobile wants to desperately move its user base to 4G. For 3G it was stuck with TD-SCDMA or the TDD LCR option. This 3G technology is not as good as its FDD variant, commonly known as UMTS.

This trend of migrating to 4G is not unique to China. A recent report (embedded below) by 4G Americas predicts that by the end of 2018, HSPA/HSPA+ would be the most popular technology whereas LTE would be making an impact with 1.3 Billion connected devices. The main reason for HSPA being so dominant is due to the fact that HSPA devices are mature and are available now. LTE devices, even though available are still slightly expensive. At the same time, operators are taking time having a seamless 4G coverage throughout the region. My guess would be that the number of devices that are 4G ready would be much higher than 1.3 Billion.

It is interesting to see that the number of 'Non-Smartphones' remain constant but at the same time, their share is going down. It would be useful to breakdown the number of Smartphones into 'Phablets' and 'non-Phablets' category.

Anyway, the 4G Americas report from which the information above is extracted contains lots of interesting details about Release-11 and Release-12 HSPA+ and LTE. The only problem I found is that its too long for most people to go through completely.

The whitepaper contains the following information:

3GPP Rel-11 standards for HSPA+ and LTE-Advanced were frozen in December 2012 with the core network protocols stable in December 2012 and Radio Access Network (RAN) protocols stable in March 2013. Key features detailed in the paper for Rel-11 include:
HSPA+:
  • 8-carrier downlink operation (HSDPA)
  • Downlink (DL) 4-branch Multiple Input Multiple Output (MIMO) antennas
  • DL Multi-Flow Transmission
  • Uplink (UL) dual antenna beamforming (both closed and open loop transmit diversity)
  • UL MIMO with 64 Quadrature Amplitude Modulation (64-QAM)
  • Several CELL_FACH (Forward Access Channel) state enhancements (for smartphone type traffic) and non-contiguous HSDPA Carrier Aggregation (CA)
LTE-Advanced:
  • Carrier Aggregation (CA)
  • Multimedia Broadcast Multicast Services (MBMS) and Self Organizing Networks (SON)
  • Introduction to the Coordinated Multi-Point (CoMP) feature for enabling coordinated scheduling and/or beamforming
  • Enhanced Physical Control Channel (EPDCCH)
  • Further enhanced Inter-Cell Interference Coordination (FeICIC) for devices with interference cancellation
Finally, Rel-11 introduces several network and service related enhancements (most of which apply to both HSPA and LTE):
  • Machine Type Communications (MTC)
  • IP Multimedia Systems (IMS)
  • Wi-Fi integration
  • Home NodeB (HNB) and Home e-NodeB (HeNB)
3GPP started work on Rel-12 in December 2012 and an 18-month timeframe for completion was planned. The work continues into 2014 and areas that are still incomplete are carefully noted in the report.  Work will be ratified by June 2014 with the exception of RAN protocols which will be finalized by September 2014. Key features detailed in the paper for Rel-12 include:
HSPA+:
  • Universal Mobile Telecommunication System (UMTS) Heterogeneous Networks (HetNet)
  • Scalable UMTS Frequency Division Duplex (FDD) bandwidth
  • Enhanced Uplink (EUL) enhancements
  • Emergency warning for Universal Terrestrial Radio Access Network (UTRAN)
  • HNB mobility
  • HNB positioning for Universal Terrestrial Radio Access (UTRA)
  • Machine Type Communications (MTC)
  • Dedicated Channel (DCH) enhancements
LTE-Advanced:
  • Active Antenna Systems (AAS)
  • Downlink enhancements for MIMO antenna systems
  • Small cell and femtocell enhancements
  • Machine Type Communication (MTC)
  • Proximity Service (ProSe)
  • User Equipment (UE)
  • Self-Optimizing Networks (SON)
  • Heterogeneous Network (HetNet) mobility
  • Multimedia Broadcast/Multicast Services (MBMS)
  • Local Internet Protocol Access/Selected Internet Protocol Traffic Offload (LIPA/SIPTO)
  • Enhanced International Mobile Telecommunications Advanced (eIMTA) and Frequency Division Duplex-Time Division Duplex Carrier Aggregation (FDD-TDD CA)
Work in Rel-12 also included features for network and services enhancements for MTC, public safety and Wi-Fi integration, system capacity and stability, Web Real-Time Communication (WebRTC), further network energy savings, multimedia and Policy and Charging Control (PCC) framework.


Sunday, 1 December 2013

Quick summary on LTE and UMTS / HSPA Release-12 evolution by 3GPP



A quick summary from 3GPP about the Release-12 progress (Jun. 2014 release planned) from the recent ETSI Future Mobile Summit. Presentation and video embedded below





Sunday, 27 October 2013

TDD-FDD Joint CA


From a recent NTT Docomo presentation (embedded below). Whereas right now 3GPP has only been working on FDD or TDD scenarios, this proposal is a combination of FDD as P-Cell and TDD as S-Cell. Inter-Technology carrier aggregation is another possible option. Anyway, the complete presentation is below.


LTE-Advanced Enhancements and Future Radio Access Toward 2020 and Beyond from Zahid Ghadialy

Updated on 29/10/2013

3GPP has already started working on this work item. See RP-131399 for details.

Thursday, 5 September 2013

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.

Saturday, 29 June 2013

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.

Monday, 24 June 2013

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.

Monday, 3 June 2013

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:



Wednesday, 24 April 2013

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.


Monday, 1 April 2013

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).


Monday, 25 February 2013

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


Wednesday, 23 January 2013

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.






Friday, 11 January 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_UEPCOPMTCe_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.

Wednesday, 5 December 2012

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:



You can download the PPT from Slideshare.

Other related posts:


Sunday, 18 November 2012

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.