Showing posts with label Release 10. Show all posts
Showing posts with label Release 10. Show all posts

Wednesday, 5 January 2011

eICIC: Enhanced inter-cell interference coordination in 3GPP Release-10

Inter-cell interference coordination (ICIC) was introduced in Release-8/9 of the 3GPP LTE standards. The basic idea of ICIC is keeping the inter-cell interferences under control by radio resource management (RRM) methods. ICIC is inherently a multi-cell RRM function that needs to take into account information (e.g. the resource usage status and traffic load situation) from multiple cells.

Broadly speaking, the main target of any ICIC strategy is to determine the resources (bandwidth and power) available at each cell at any time. Then (and typically), an autonomous scheduler assigns those resources to users. Thus, from the Radio Resource Control perspective, there are two kind of decisions: (a) which resources will be allocated to each cell? and, (b) which resources will be allocated to each user?. Clearly, the temporality of such decisions is quite different. Whereas resources to users allocation is in the order of milliseconds, the allocation of resources to cells take much longer periods of time or can be fixed.

Static ICIC schemes are attractive for operators since the complexity of their deployment is very low and there is not need for new extra signaling out of the standard. Static ICIC mostly relies on the fractional reuse concept. This means that users are categorized according to their Signal-to-Noise-plus-Interference Ratio (SINR), that means basically according to their inter-cell interference, and different reuse factors are applied to them, being higher at regions with more interference, mostly outer regions of the cells. The total system bandwidth is divided into sub-bands which are used by the scheduler accordingly.

A simple way to explain ICIC is based on picture above. The users are divided into two categories, one is Cell Center User (CCU), and the other one is Cell Edge User (CEU). CCUs are the users distributed in the gray region of above figure, and CEUs are the users distributed in the above red, green and blue areas. CCU can use all the frequencypoints to communicate with the base station, while CEU must use corresponding specified frequency points to ensure orthogonality between different cells.
CEUs can be assigned a higher transmissionpower for the frequency reuse factor is greater than 1. The frequency points are not overlapped at the edges so the adjacent cell interference is small. CCU’s frequency reuse factor is 1; for the path loss is small and transmission power is low. Therefore the interference to the adjacent cells is not high either.

Dominant interference condition has been shown when Non-CSG/CSG users are in close proximity of Femto, in this case, Rel8/9 ICIC techniques are not fully effective in mitigating control channel interference, and hence, Enhanced interference management is needed At least the following issues should be addressed by any proposed solutions:
o Radio link monitoring (RLM)
o Radio Resource Management (including detection of PSS/SSS and PBCH)
o Interference from CRS
oo To PCFICH/PHICH/PDCCH
oo To PDSCH
o CSI measurement
o Interference from PDCCH masked with P-RNTI and SI-RNTI (for SIB-1 only) and associated PCFICH

As a result, from Release-10 onwards eICIC work was started. In Rel-10, two eICIC or Enhanced inter-cell interference coordination (also incorrectly referred to as Enhanced Inter-Cell Interference Cancellation) were being actively discussed. They are Time domain eICIC and autonomous HeNB power setting. More advanced ideas are being thought of beyong Rel-10 including Interference management techniques on carrier resolution ( optimally exploiting available Networks frequency assets (carriers in same or different bands) , combination with Carrier Aggregation; interference management schemes proposed both during LTE-Advanced Study Item phase, and during Rel-10 HetNet eICIC work.

From an earlier presentation in SON Conference:

eICIC:
- Effectively extends ICIC to DL control - time domain
- Requires synchronization at least between macro eNB and low power eNBs in its footprint
- No negative impact on legacy Rel 8 Use

Range Extension(RE)
- Refers to UE ability to connect and stay connected to a cell with low SINR
- Achieved with advanced UE receivers - DL interference cancellation (IC)

RE + eICIC technique:
– Eliminates coverage holes created by closed HeNBs
– Improves load balancing potential for macro network with low power eNBs and leads to significant network throughput increase
–Enables more UEs can be served by low power eNBs, which can lead to substantially higher network throughput

More details on eICIC is available in 3GPP CR's and TR's listed below:
  • R1-105081: Summary of the description of candidate eICIC solutions, 3GPP TSG-WG1 #62, Madrid, Spain, August 23rd – 27th, 2010.
  • R1-104942: Views on eICIC Schemes for Rel-10, 3GPP TSG RAN WG1 Meeting #62, Madrid, Spain, 23-27 August, 2010.
  • R1-104238: eICIC Chairman’s note, 3GPP TSG RAN WG1 Meeting #61bis, Dresden, Germany, 28th June – 2nd July 2010.
  • R1-103822: Enhanced ICIC considerations for HetNet scenarios, 3GPP TSG RAN WG1 #61bis Meeting, Dresden, Germany, June 28 – July 2, 2010.
You can also check out NTT Docomo's presentation on LTE Enhancements and Future Radio Access here.

Wednesday, 15 December 2010

SON in Heterogeneous Networks

Another presentation from the SON 2010 Conference based on yesterdays theme of HetNets.


Presented by Seungpyo Hong of Institute of Network Technology, SK Telecom.

Thursday, 9 December 2010

Minimization of Drive Tests (MDT) in 3GPP Release-10

Another one that came from the SON conference.

At present, the network optimisation after it is operational is generally done by drive testing. In this an equipment (test mobile) that collects measurements and location information collects all the required information while the equipment is being driven in a car on the roads and this information is used offline to analyse the coverage in different locations and based on that the parameters, power, antenna locations, antenna tilts, etc. are optimised. After the changes to any of the optimisation paramaters, drive test has to be undertaken again to make sure that the impact of these changes are positive.

One more thing that has to be taken account of is that the drive tests have to be carried out at di9ffert times to be able to predeict the behaviour at different loads.

Using drive tests for network optimization purposes is costly and causes also additional CO2 emissions, so it is desirable to develop automated solutions, including involving UEs in the field, in 3GPP to reduce the operator costs for network deployment and operation. The studies done as part of the study item phase [1] have shown that it is beneficial to collect UE measurements to enable a more efficient network optimisation and it is feasible to use control plane solutions to acquire the information from devices. This information, together with information available in the radio access network can be used for Coverage Optimization purposes.

It should be remembered that drive tests form a big part of the Network opex and Deutsche Telekom for example expects a 40% cost saving with SON (and MDT is a part of that)

Goal of MDT in 3GPP Rel.10
– Automatic UE measurements collection and data logging used to replace the manual drive testing that the operators have to perform in their networks
– Evaluation of network performance per physical location
– For both HSPA & LTE


There are two different types of MDT:

Immediate MDT: MDT functionality involving measurement performance by UE in CONNECTED state and reporting of the measurements to eNB/RNC available at the time of reporting condition.

Logged MDT: MDT functionality involving measurement performance by UE in IDLE state at points in time when configured conditions are satisfied, its storage in measurement log for reporting to eNB/RNC at a later point in time.

The solutions for MDT shall be able to work independently from SON support in the network. Relation between measurements/solution for MDT and UE side SON functions shall be established in a way that re-use of functions is achieved where possible.

• Use cases
– 3GPP R10: Coverage optimization : Prio1
– For 3GPP > R10 :Capacity optimization, Mobility optimization, Parameterization of common channels, QoS verification, no specific measurements
- In Release-11 MDT Enhancements and evaluation of other MDT use cases, such as ”Parameterization of common control channels” and Positioning enhancements will be explored.

• MDT and SON
– MDT is about UE measurement collection for off-line processing No automatic mechanism is defined MDT
– SON is aiming at instantaneous/automated reaction on short to middle term network issues

It should be noted that MDT is a wide area and some of the boundaries between MDT and SON are a bit fuzzy. One of the other ways for SON is to enable detected cell measurements in the handset. This will give the indication about the cells that are not in the monitored set but the UE is able to see.

The RRC (control plane) measurements for LTE are not advanced enough and there are no measurements for UE position. On the other hand for UMTS/HSPA the UE positioning measurements could be used to report the exact location at the point of measurements. There are some discussions for enhancing the LTE measurements to include the longitude, latitude, altitude, velocity and even direction (too ambitious?).

Finally it should be pointed out that UE based reporting based on the User Plane Measurements (typically done by the operator installing a small application on the handset) can be performed by the operator in case a user is reporting poor coverage or failure in an area. Since these are proprietary applications, the operator can collect variety of information including but not limited to, position information, crrent cell and neighbour cell power levels, etc.

With all the control plane measurements and user plane measurements, the battery life could be severely affected and it has to be made sure that these are done very seldomly or with users permission.

Some of the things mentioned above may not be exactly true and if you know better please feel free to correct me.

[1] 3GPP TR 36.805 - Study on Minimization of drive-tests in Next Generation Networks

[2] 3GPP TS 37.320 - Universal Terrestrial Radio Access (UTRA) and Evolved Universal Terrestrial Radio Access (E-UTRA); Radio measurement collection for Minimization of Drive Tests (MDT); Overall description; Stage 2 (Release 10)

Tuesday, 7 December 2010

SON framework in 3GPP

From a Presentation by Cinzia Sartori from Nokia Siemens Networks (NSN) in the Self-Organising Networks Conference in London, Nov. 2010

Release 8 functionality
• Self-configuration procedures

Release 9 enhancements
• Self-optimization procedures
• Energy Saving Intra-RAT

Release 10 objectives
• Extend Self-optimization procedures , including inter-RAT
• Minimization of Drive Test (MDT)
• Energy Saving extension, including Multi-RAT (Study Item)
• 3G-ANR
• SON Conflict Resolution

SON features for R11 (Probably - Under Discussion)
• Minimization of Drive Tests (MDT) enhancements
• Mobility Robustness Optimization for MultiRAT
• SON for LTE-A features defined in Rel.10
•• Hetrogeneous Networks aka. HetNet?
•• SON for Relays
•• SON for Carrier Aggregation

Thursday, 25 November 2010

LIPA, SIPTO and IFOM Comparison

Enhancing macro radio access network capacity by offloading mobile video traffic will be essential for mobile communications industry to reduce its units costs to match its customer expectations. Two primary paths to achieve this are the use of femtocells and WiFi offloading. Deployment of large scale femtocells for coverage enhancement has been a limited success so far. Using them for capacity enhancements is a new proposition for mobile operators. They need to assess the necessity of using them as well as decide how to deploy them selectively for their heavy users.

Three alternative architectures that are being standardized by 3GPP have various advantages and shortcomings. They are quite distinct in terms of their dependencies and feasibility. Following table is a summary of comparison among these three approaches for traffic offloading.


Looking at the relative strengths of the existing traffic offload proposals, it is difficult to pick an outright winner. SIPTO macro-network option is the most straight-forward and most likely to be implemented rather quickly. However, it doesn't solve the fundamental capacity crunch in the radio access network. Therefore its value is limited to being an optimization of the packet core/transport network. Some other tangible benefits would be reduction in latency to increase effective throughput for customers as well as easier capacity planning since transport facilities don't need to be dimensioned for large number of radio access network elements anymore.

LIPA provides a limited benefit of allowing access to local premises networks without having to traverse through the mobile operator core. Considering it is dependent on the implementation of femtocell, this benefit looks rather small and has no impact on the macro radio network capacity. If LIPA is extended to access to Internet and Intranet, then the additional offload benefit would be on the mobile operator core network similar to the SIPTO macro-network proposal. Femtocell solves the macro radio network capacity crunch. However, the pace of femtocell deployments so far doesn't show a significant momentum. LIPA's market success will be limited until cost of femtocell ownership issues are resolved and mobile operators decide why (coverage or capacity) to deploy femtocells.

IFOM is based upon a newer generation of Mobile IP that has been around as a mobile VPN technology for more than 10 years. Unfortunately success record of mobile IP so far has been limited to enterprise applications. It hasn't become a true consumer-grade technology. Introduction of LTE may change this since many operators spearheading LTE deployments are planning to use IPv6 in handsets and adopt a dual-stack approach of having both IPv4 and IPv6 capability. Since many WiFi access networks will stay as IPv4, DSMIPv6 will be the best tunneling mechanism to hide IPv6 from the access network. Having dual-stack capability will allow native access to both legacy IPv4 content and native IPv6 content from major companies such as Google, Facebook, Yahoo, etc. without the hindrance of Network Address Translation (NAT). Considering the popularity of smartphones such as iPhone, Blackberry and various Android phones, they will be the proving ground for the feasibility of DSMIPv6.

Source of the above content: Whitepaper - Analysis of Traffic Offload : WiFi to Rescue


Wednesday, 24 November 2010

IP Flow Mobility and Seamless Offload (IFOM)

Unlike LIPA or SIPTO that are dependent on upstream network nodes to provide the optimization of routing different types of traffic, IFOM relies on the handset to achieve this functionality. It explicitly calls for the use of simultaneous connections to both macro network, e.g., LTE, UMTS and WiFi. Therefore, IFOM, unlike LIPA and SIPTO, is truly a release 10-onward only technology and it is not applicable for user terminals pre-Release 10. IFOM is being specified via 3GPP TS 23.261 [1]. Following diagram shows the interconnectivity model for IFOM capable UE.


IFOM uses an Internet Engineering Task Force (IETF) Request For Comments (RFC), Dual Stack Mobile IPv6 (DSMIPv6) (RFC-5555) [2].

Since IFOM is based on DSMIPv6, it is independent of the macro network flavor. It can be used for a green-field LTE deployment as well as a legacy GPRS packet core.

Earlier on we looked at the mobile network industry attempts of integration between packet core and WLAN networks. Common characteristic of those efforts was the limitation of the UE, its ability to use one radio interface at a time. Therefore, in earlier interworking scenarios UE was forced to use/select one radio network and make a selection to move to an alternative radio for all its traffic. Today many smartphones, data cards with connection managers already have this capability, i.e., when the UE detects the presence of an alternative access network such as a home WiFi AP, it terminates the radio bearers on the macro network and initiates a WiFi connection. Since WiFi access network and packet core integration is not commonly implemented, user typically loses her active data session and re-establishes another one.

Similarly access to some operator provided services may not be achieved over WiFi. Considering this limitation both iPhone IOS and Android enabled smartphones to have simultaneous radio access but limited this functionality to sending MMS over the macro network while being connected to WiFi only.

IFOM provides simultaneous attachment to two alternate access networks. This allows fine granularity of IP Flow mobility between access networks. Using IFOM, it will be possible to select particular flows per UE and bind them to one of two different tunnels between the UE and the DSMIPv6 Home Agent (HA) that can be implemented within a P-GW or GGSN. DSMIPv6 requires a dual-stack (IPv4 or IPv6) capable UE. It is independent of the access network that can be IPv4 or IPv6.

[1] 3GPP TS 23.261: IP flow mobility and seamless Wireless Local Area Network (WLAN) offload; Stage 2

[2] RFC-5555: Mobile IPv6 Support for Dual Stack Hosts and Routers

[3] 3GPP TS 23.327: Mobility between 3GPP-Wireless Local Area Network (WLAN) interworking and 3GPP systems

Content Source: Analysis of Traffic Offload : WiFi to Rescue

Monday, 22 November 2010

Carrier aggregation deployment scenarios for Release-10 LTE-A

One of the important aspects to consider is that carrier aggregation should allow aggregation of not only the existing bands, but also bands that are introduced in future, e.g., 3.5 GHz band, etc. While existing bands already have certain deployments, new deployments can be considered for new bands that are introduced. Since introduction of new bands is done in a release independent fashion, considerations for such future bands are essential already in Rel-10. When higher frequencies such as 3.5 GHz are considered, path loss can be significant (e.g., 4-10 dB difference in link budget) when compared to 2 GHz. Hence, the most efficient deployment may not be to stick with the traditional macro-overlaying approach. Carrier aggregation should allow more flexible use of such new bands, since coverage and mobility can be ascertained by the existing band deployments, e.g., 2 GHz.

Picture below shows some of the potential deployment scenarios for carrier aggregation. Note that the scenarios listed are non-exhaustive. For example, other scenarios using repeaters and femto cells may be considered. Also note that F2 > F1.




Scenario 1
* F1 and F2 cells are co-located and overlaid, providing nearly the same coverage
* Both layers provide sufficient coverage and mobility can be supported on both layers.
* Likely scenario when F1 and F2 are of the same band, e.g., 2 GHz, 800 MHz, etc.
* It is expected that aggregation is possible between overlaid F1 and F2 cells.

Scenario 2
* F1 and F2 cells are co-located and overlaid, but F2 has smaller coverage due to larger path loss
* Only F1 provides sufficient coverage and F2 is used to provide throughput. Mobility is performed based on F1 coverage.
* Likely scenario when F1 and F2 are of different bands, e.g., F1 = {800 MHz, 2 GHz} and F2 = {3.5 GHz}, etc.
* It is expected that aggregation is possible between overlaid F1 and F2 cells.

Scenario 3
* F1 and F2 cells are co-located but F2 antennas are directed to the cell boundaries of F1 so that cell edge throughput is increased
* F1 provides sufficient coverage but F2 potentially has holes, e.g., due to larger path loss. Mobility is based on F1 coverage.
* Likely scenario when F1 and F2 are of different bands, e.g., F1 = {800 MHz, 2 GHz} and F2 = {3.5 GHz}, etc.
* It is expected that F1 and F2 cells of the same eNB can be aggregated where coverage overlap.

Scenario 4
* F1 provides macro coverage and on F2 Remote Radio Heads (RRHs) are used to provide throughput at hot spots
* Mobility is performed based on F1 coverage.
* Likely scenario when F1 and F2 are of different bands, e.g., F1 = {800 MHz, 2 GHz} and F2 = {3.5 GHz}, etc.
* It is expected that F2 RRE cells can be aggregated with the underlying F1 macro cells.

Scenario 5
* Similar to scenario #2, but frequency selective repeaters are deployed so that coverage is extended for one of the carrier frequencies

Scenarios supported in Rel-10 time frame
* For DL, all scenarios are supported in Rel-10
* For UL, scenario 4 and 5 are not supported in Rel-10

Source: R2-100531 CA deployment scenario NTT DOCOMO

Friday, 19 November 2010

CA (Carrier Aggregation) Scenarios in LTE-Advanced

CA (Carrier Aggregation) may be used in three different spectrum scenarios as follows.

Intraband Contiguous CA — This is where a contiguous bandwidth wider than 20 MHz is used for CA. Although this may be a less likely scenario given frequency allocations today, it can be common when new spectrum bands like 3.5 GHz are allocated in the future in various parts of the world. The spacing between center frequencies of contiguously aggregated CCs (Component Carriers) is a multiple of 300 kHz to be compatible with the 100 kHz frequency raster of Release 8/9 and preserving orthogonality of the subcarriers with 15 kHz spacing.

Intraband Non-Contiguous CA — This is where multiple CCs belonging to the same band are used in a non-contiguous manner. This scenario can be expected in countries where spectrum allocation is non-contiguous within a single band, when the middle carriers are loaded with other users, or when network sharing is considered.

Interband Non-Contiguous CA — This is where multiple CCs belonging to different bands (e.g., 2 GHz and 800 MHz are aggregated). With this type of aggregation, mobility robustness can potentially be improved by exploiting different radio propagation characteristics of different bands. This form of CA may also require additional complexity in the radio frequency (RF) front-end of UE. In LTE Release 10, for the UL the focus is on intraband CA, due to difficulties in defining RF requirements for simultaneous transmission on multiple CCs with large frequency separation, considering realistic device linearity. For the DL, however, both intra and interband cases are considered in Release 10, while specific RF requirements are being developed.

Text Source: Carrier Aggregation Framework in 3GPP LTE-Advanced - Mikio Iwamura et al. in IEEE Communications Magazine August 2010

Picture Source: http://www.catr.cn/tecm/dxwjs/201006/t20100610_1143968.htm

Monday, 8 November 2010

Single Radio Voice Call Continuity (SR‐VCC)

From a 3GPP presentation by Hannu Hietalahti

1. SR-VCC use case
1a. IMS call initiated in LTE can continue in CS domain after moving outside of LTE coverage area
1b. SR-VCC is invoked if no other VoIP capable PS system (e.g., HSPA/eHRPD) is available for VoIP PS-PS HO (Handovers)
1c. Only HO of a single voice bearer from PS to CS is specified
1d. Requires overlapping with 1xRTT/GSM/WCDMA coverage

2. SR-VCC allows a voice calls are anchored in IMS
2a. One-way HO from PS to CS systems (LTE to GSM/UMTS or LTE to 1xRTT)
2b. No simultaneous operation of different radio transceivers needed

3. Rel-9 SR-VCC improvements
3a. IMS support of mid call services (e.g., HOLD, MPTY)
3b. SR-VCC support for emergency calls

4. Video calls, reverse direction from CS call to IMS and optimisations are being studied in Rel-10

Monday, 1 November 2010

ETSI M2M Workshop summary and conclusions

As I mentioned earlier about the M2M workshop held in Paris, the following are the highlights from press release after the event:

ETSI's first Open Machine-to-Machine Workshop broke all records for attendance, laying out the next steps for achieving M2M applications worldwide, and confirming a leading role for the standards organisation.

'Machine-to-Machine (M2M) communications need standards – and ETSI is taking the lead to make sure that the standards are in place.' This was the main conclusion from ETSI's M2M workshop which took place on 19 and 20 October. With over 220 attendees from across the world, this was the most popular ETSI workshop to date, with the high degree of interest reflecting the enormous potential that is foreseen for M2M applications and technologies.

Participants heard how existing and evolving communication technologies networks (mostly wireless (cellular and low-power), but also fixed networks, including power line communications) provide a firm basis for connecting M2M sensors and applications. Specification of appropriate interfaces that allow network technology neutrality is a priority, and one that ETSI is already addressing.

The workshop included two live demonstrations organised by InterDigital Inc. These demonstrated an M2M gateway and core network, and an M2M Wireless Personal Area Network (sensors connecting via low-power wireless devices to a database, simulating e-Health, home automation and security application scenarios). The implementations were based on current specifications from ETSI's M2M Technical Committee and confirmed both the effectiveness of the implications and of the ETSI specifications. In addition, poster sessions presented the work of six research and development projects related to M2M and the Future Internet, part of the European Commission's 7th Framework Programme (FP7).

The standards work of ETSI's M2M Technical Committee is reaching an advanced stage, and many network operators are encouraging a first release of M2M standards by early 2011. The committee is currently finalising the architecture for the service platform that will enable the integration of multiple vertical M2M applications. The workshop confirmed that ETSI is well placed to address a vital aspect of standardisation in support of M2M – the specification of interfaces that will facilitate the interconnection and interoperability of the diverse applications and of the networks that will underlie them.

Marylin Arndt of France Telecom, Chairman of ETSI's M2M Technical Committee, said: 'The committee will continue in its role of creating standards that build on what we already have, to ensure that the emerging 'vertical' M2M applications can be supported effectively. At the same time, the committee (and ETSI in general) has a vital responsibility to co-ordinate and direct the wider work on M2M. We are here to lead the way.'

All presentations could be downloaded from here.

The conclusions from the meeting is summarised in the presentation embedded below:

Tuesday, 19 October 2010

LTE Self Optimizing Networks (SON) enhancements for Release-10

Capacity and Coverage Optimisation (CCO) was already nominally part of the Release-9 WI, but could not be completed due to amount of work related to other use cases.

Energy Savings are a very important topic, especially for operators, as solutions derived for this use case can significantly limit their expenses. According to TR 36.902 this solution should concern switching off cells or whole base stations. This may require additional standardised methods, once there is need identified for.

Basic functionality of Mobility Load Balancing (MLB) and Mobility Robustness Optimisation (MRO), also listed in TR 36.902, were defined in Rel.9. However, successful roll-out of the LTE network requires analysing possible enhancements to the Rel.9 solutions for MLB and MRO. In particular, enhancements that address inter-RAT scenarios and inter-RAT information exchange must be considered. These enhancements should be addressed in Rel.10.

There may also be other use cases for LTE for which SON functionality would bring optimisations.

Although, it is of primary interest to provide coverage to users during a roll-out, it is equally important to enhance the capacity of the network during operation. As such, both coverage and capacity are considered in the use case and supported by the SON function. The CCO SON function should be configured through appropriate objectives and targets in order to meet the operator’s requirement on coverage and capacity, and the prioritization between them.

The following use cases and scenarios are planned for Release-10:

Coverage and Capacity Optimisation (CCO)
The use case is to enable detection of following problems:
Priority 1: coverage problems, e.g. coverage holes
Priority 2: capacity problems

Mobility Robustness Optimisation (MRO) enhancements
The use case is to enable detection and to provide tools for possible correction of following problems:
Connection failures in inter-RAT environment:
o Priority 1: at HOs from LTE to UMTS/GSM
o Priority 2: at HOs from UMTS/GSM to LTE
Obtaining UE measurements in case of unsuccessful re-establishment after connection
failure
Ping-pongs in idle mode (inter-RAT and intra-LTE environment)
Ping-pongs in active mode (inter-RAT)
HO to wrong cell (in intra-LTE environment) that does not cause connection failure (e.g. short stay problem)

Mobility Load Balancing (MLB) enhancements
The use case is to fulfil following objectives:
Improving reliability of MLB in intra-LTE scenarios
Improving functionality of the MLB in inter-RAT scenarios (the transport method agreed for R9 should be used for R10).

For more info see 3GPP TS 32.521: Self-Organizing Networks (SON) Policy Network Resource Model (NRM) Integration Reference Point (IRP); Requirements; Release-10

There is also a Self-Organising Networks Conference that I am attending next month and I plan to give SON lots of coverage before and after the event.

If you havent read the 3G Americas whitepaper on SON, it is definitely worth a read. I have embedded it below.



Friday, 15 October 2010

Network Improvements for Machine Type Communications (NIMTC)

I have blogged about M2M before here.

The Release 10 work item Network Improvements for Machine Type Communications – Stage 1 for NIMTC specified a number of requirements to make the network more suitable for machine type communications. Additional aspects need to be studied before proceeding with their potential inclusion in the normative work.

In the course of the Release 10 work item, it was decided to leave out MTC Device to MTC Device communications from Release 10. This because it was felt it was not possible to do it justice within the Release 10 time frame. Nevertheless, MTC Device to MTC Device communications are expected to become of major importance, especially with consumer devices communicating directly to each other. Therefore, this work item aims to study the network improvements requirements of MTC Device to MTC Device scenarios. A particular aspect of MTC Device to MTC Device scenarios is the identification and functionality needed to set up a connection towards a MTC Device. The IMS domain may provide a solution for this required functionality. In this case the impacts and requirements of MTC on IMS needs to be studied.

Additionally MTC Devices often act as a gateway for a capillary network of other MTC Devices or non-3GPP devices. These gateway MTC Devices may have specific requirements on the mobile network, which have not yet been taken into account in the Release 10 NIMTC work item. Study is needed to determine to what extent improvements are needed and can be specified by 3GPP for MTC Devices that act as a gateway for 'capillary networks' of other devices. Also alignment with what is specified by ETSI TC M2M on this aspect is needed.

Further optimisations may be possible for (groups of) MTC Devices that are co-located. An example of this could be a car with a number of different MTC Devices that always move along together. Optimisations for these kind of scenarios have been suggested, but have not yet been taken into account in the Release 10 NIMTC. Study is needed to determine to what extent network improvements can be specified for co-located MTC Devices.

Because of the different characteristics of Machine-Type Communications, the optimal network for MTC may not be the same as the optimal network for human to human communications. Optimisations of network selections and steering of roaming may be needed. Study is needed to determine to what extent improvements are needed on network selection and steering of roaming for MTC.

Many MTC applications use some kind of location tracking. E.g. the existing LCS framework could be used to provide location information for these kinds of MTC applications. Study is needed to determine to what extent improvements are needed for MTC location tracking.

MTC brings a new concept of a MTC User and MTC Server. So far little attention has been given to service requirements on the communication between the network and the MTC User/MTC Server. Also alignment with what is specified by ETSI TC M2M on that aspect is needed. Study is needed on what kind of service requirements are needed and can be specified by 3GPP.

The Objective of Study on enhancements for Machine-Type Communications item is to study additional requirements, use cases and functionality beyond that specified by the Release 10 NIMTC work item on the following aspects:

network improvements for MTC Device to MTC Device communications via one or more PLMNs. Note: direct-mode communication between devices is out of scope.
possible improvements for MTC Devices that act as a gateway for 'capillary networks' of other devices. Note: capillary networks themselves are out of scope of 3GPP.
network improvements for groups of MTC Devices that are co-located with other MTC Devices
improvements on network selection mechanisms and steering of roaming for MTC devices
possible enhancements to IMS to support MTC
possible improvements for location tracking of MTC Devices
service requirements on communications between PLMN and the MTC User/MTC Server (e.g. how the MTC User can set event to be monitored with MTC Monitoring);
possible service requirements to optimize MTC Devices
possible New MTC Features to further improve the network for MTC

The results of the study will be recorded in a Technical Report. Work ongoing in external standard organization shall be considered (e.g. ETSI M2M, CCSA TC 10).

The European Telecommunications Standards Institute (ETSI) now has a Technical Committee exclusively focused on M2M; the Chinese Communications Standards Association (CCSA) is currently exploring the definition of M2M standards for China and the Geneva-headquartered International Telecommunications Union (ITU) is working on “mobile wireless access systems providing telecommunications for a large number of ubiquitous sensors and/or actuators scattered over wide areas in the land mobile service,” which are at the center of the M2M ecosystem.

Closer to us, the US Telecommunications Industry Association (TIA) has also launched a new engineering committee centered on Smart Device Communications (TIA TR-50). Incidentally, at Global Standards Collaboration 15 (GSC-15), which will be held on August 30- September 2, 2010 in Beijing and hosted by CCSA, the world’s leading telecommunications and radio standards organizations will meet to promote innovation and collaboration on a broad spectrum of standards topics among which M2M has been identified as a “High Interest Subject.”

Related subject on 3GPP here.

M2M workshop is happening in ETSI next week. More details here.

Definitions:

MTC Device: A MTC Device is a UE equipped for Machine Type Communication, which communicates through a PLMN with MTC Server(s) and/or other MTC Device(s).

Local-Access Device: A Local-Access Device is a device in MTC Capillary Network, which has no 3GPP mobile communication capability.

MTC Capillary Network: An MTC Capillary Network is a network of devices that provides local connectivity between devices within its coverage and MTC Gateway Device.

MTC Gateway Device: An MTC Gateway Device is an MTC device equipped for Machine Type Communication, which acts as a gateway for a group of co-located MTC Devices or to connect MTC Devices and/or Local-Access Devices in an MTC Capillary Network to communicate through a PLMN with MTC Server(s), and/or other MTC Device(s).

Further Interesting Reading:



Tuesday, 5 October 2010

3GPP Green activities / Energy Saving initiatives


3GPP has been working on Energy saving initiatives for Release-10 and Release-11. Here is a very quick summary of some of these items.

Telecommunication management; Study on Energy Savings Management (ESM)

Most mobile network operators aim at reducing their greenhouse emissions, by several means such as limiting their networks' energy consumption.

In new generation Radio Access Networks such as LTE, Energy Savings Management function takes place especially when mobile network operators want e.g. to reduce Tx power, switch off/on cell, etc. based on measurements made in the network having shown that there is no need to maintain active the full set of NE capabilities.

By initiating this Work Item about Energy Savings Management, 3GPP hopes to contribute to the protection of our environment and the environment of future generations.

The objective of this technical work is to study automated energy savings management features. Usage of existing IRPs is expected as much as possible, e.g. Configuration Management IRP, etc. However, this technical work may identify the need for defining a new IRP.

The following operations may be considered in this study item (but not necessarily limited to):
• Retrieval of energy consumption measurements
• Retrieval of traffic load measurements
• Adjust Network Resources capabilities


OAM aspects of Energy Saving in Radio Networks

There are strong requirements from operators on the management and monitoring of energy saving functions and the evaluation of its impact on the network and service quality. Therefore an efficient and standardized Management of Energy Saving functionality is needed. Coordination with other functionalities like load balancing and optimization functions is also required.

The objectives of this work item are:
• Define Energy Savings Management OAM requirements and solutions for the following use cases,
• eNodeB Overlaid
• Carrier restricted
• Capacity Limited Network
• Define OAM requirements and solutions for coordination of ESM with other functions like
• Self-Optimization
• Self Healing
• Traditional configuration management
• Fault Management
• Select existing measurements which can be used for assessing the impact and effect of Energy Saving actions corresponding to above Energy Saving use cases.
• Define new measurements which are required for assessing the impact and effect of Energy Saving actions, including measurements of the energy consumption corresponding to above Energy Saving use cases.


Study on impacts on UE-Core Network signalling from Energy Saving

Energy Saving (ES) mechanisms are becoming an integral part of radio networks, and consequently, of mobile networks. Strong requirements from operators (for reasons of cost and environmental image) and indirectly from authorities (for the sake of meeting overall international and national targets) have been formulated. With the expected masses of mobile network radio equipment as commodities, in the form of Home NB/eNBs, this aspect becomes even more crucial.

It is necessary to ensure that ES does not lead to service degradation or inefficiencies in the network. In particular:
• the activation status of radio stations (on/off) introduces a new scale of dynamicity for the UE and network;
• mass effects in signalling potentially endanger the network stability and need to be handled properly.

It is unclear whether and how currently defined procedures are able to cope with, and eventually can be optimized for, ES conditions; thus a systematic study is needed.

The study aims, within the defined CT1 work areas, at:
• analysing UE idle mode procedures and UE-Core Network signalling resulting from frequent switch on/off of radio equipment in all 3GPP accesses, including home cell deployment and I-WLAN;
• performing a corresponding analysis for connected mode UEs;
• analysing similar impacts from activation status of non-3GPP access networks;
• documenting limitations, weaknesses and inefficiencies in these procedures, with emphasis on mass effects in the UE-Core Network signalling;
• studying potential optimizations and enhancements to these procedures;

The study shall also evaluate and give recommendations on potential enhancements to 3GPP specifications (whether and where they are seen necessary).


Study on Solutions for Energy Saving within UTRA Node B

Due to the need to reduce energy consumption within operators’ networks, and considering the large amount of UMTS network equipment deployed in the field around the world, the standardisation of methods to save energy in UMTS Node Bs is seen as an important area of study for 3GPP.There has not been a large amount of focus on energy-saving in UMTS networks so far in 3GPP, although some solutions have been agreed in Release 9. Therefore it is proposed to start an initial study phase to identify solutions and perform any initial evaluation, such that a subset of these proposals can be used as the basis for further investigation of their feasibility.

The objective is to do an initial study to identify potential solutions to enable energy saving within UMTS Node-Bs, and do light initial evaluation of the proposed solutions, with the aim that a subset of them can be taken forward for further investigation as part of a more focused study in 3GPP.

The solutions identified in this study item should consider the following aspects:
• Impacts on the time for legacy and new UEs to gain access to service from the Node B
• Impacts on legacy and new terminals (e.g. power consumption, mobility)

Some initial indication of these aspects in relation to the proposed solutions should be provided.


Study on Network Energy Saving for E-UTRAN

The power efficiency in the infrastructure and terminal should be an essential part of the cost-related requirements in LTE-A. There is a strong need to investigate possible network energy saving mechanisms to reduce CO2 emission and OPEX of operators.

Although some solutions have been proposed and part of them have been agreed in Release-9, there has not been a large amount of attention on energy saving for E-UTRAN so far. Many potential solutions are not fully shown and discussed yet. Therefore, it is proposed to start an initial study phase to identify solutions, evaluate their gains and impacts on specifications.

The following use cases will be considered in this study item:
• Intra-eNB energy saving
• Inter-eNB energy saving
• Inter-RAT energy saving

Intra-eNB energy saving, in EUTRAN network, a single cell can operate in energy saving mode when the resource utilization is sufficiently low. In this case, the reduction of energy consumption will be mainly based on traffic monitoring with regard to QoS and coverage assurance.

A lot of work on Inter-eNB energy saving has already been done for both LTE and UTRA in Rel-9. This Study Item will investigate additional aspects (if any) on top of what was already agreed for R9.

Inter-RAT energy saving, in this use case, legacy networks, i.e. GERAN and UTRAN, provide radio coverage together with E-UTRAN. For example E-UTRAN Cell A is totally covered by UTRAN Cell B. Cell B is deployed to provide basic coverage of the voice or medium/low-speed data services in the area, while Cell A enhances the capability of the area to support high-speed data services. Then the energy saving procedure can be enabled based on the interaction of E-UTRAN and UTRAN system.

The objective of this study item is to identify potential solutions for energy saving in E-UTRAN and perform initial evaluation of the proposed solutions, so that a subset of them can be used as the basis for further investigation and standardization.

Energy saving solutions identified in this study item should be justified by valid scenario(s), and based on cell/network load situation. Impacts on legacy and new terminals when introducing an energy saving solution should be carefully considered. The scope of the study item shall be as follows:
• User accessibility should be guaranteed when a cell transfers to energy saving mode
• Backward compatibility shall be ensured and the ability to provide energy saving for Rel-10 network deployment that serves a number of legacy UEs should be considered
• Solutions shall not impact the Uu physical layer
• The solutions should not impact negatively the UE power consumption

RAN2 will focus on the Intra-eNB energy saving, while RAN3 will work on Inter-RAT energy saving and potential additional Inter-eNB energy saving technology.


Study on Solutions for GSM/EDGE BTS Energy Saving

There has not been a large amount of focus on energy-saving in GSM/EDGE networks so far in 3GPP, although some solutions have been agreed in previous Releases, notably MCBTS. Therefore it is proposed to start an initial study phase to identify solutions and perform any initial evaluation, such that a subset of these proposals can be used as the basis for further investigation of their feasibility.

The objective is to study potential solutions to enable energy saving within the BTS (including MCBTS and MSR), and evaluate each proposed solutions in detail. These potential solutions shall focus on the following specific aspects
• Reduction of Power on the BCCH carrier (potentially enabling dynamic adjustment of BCCH power)
• Reduction of power on DL common control channels
• Reduction of power on DL channels in dedicated mode, DTM and packet transfer mode
• Deactivation of cells (e.g. Cell Power Down and Cell DTX like concepts as discussed in RAN)
• Deactivation of other RATs in areas with multi-RAT deployments, for example, where the mobile station could assist the network to suspend/minimise specific in-use RATs at specific times of day
• And any other radio interface impacted power reduction solutions.

The solutions identified in this study item shall also consider the following aspects:
• Impacts on the time for legacy and new mobile stations to gain access to service from the BTS
• Impacts on legacy and new mobile stations to keep the ongoing service (without increasing drop rate)
• Impacts on legacy and new mobile stations implementation and power consumption, e.g. due to reduction in DL power, cell (re-)selection performance, handover performance, etc.
• Impacts on UL/DL coverage balance, especially to CS voice

Solutions shall be considered for both BTS energy saving non-supporting and supporting mobile stations (i.e. solutions that are non-backwards compatible towards legacy mobile stations shall be out of the scope of this study).

Thursday, 30 September 2010

RF Pattern Matching adopted in 3GPP Release-10

RF Pattern Matching is now a recognized unique location method in standards that provides carriers and OEMs with the ability to offer high accuracy location-based services that traditionally haven’t been available with low-accuracy Cell-ID based technologies. RF Pattern Matching will be incorporated into Release 10 of the 3G UMTS specifications, expected to become final in late 2010 or early 2011. This will also set the stage for opportunities to incorporate RF Pattern Matching into LTE and other future air interfaces.


“The decision to incorporate RF Pattern Matching into the 3G UMTS specifications is needed for all service providers wanting to provide the highest-SLA option for LBS as it gives them more credible options for public safety and commercial applications,” said Manlio Allegra, president and chief executive officer at Polaris Wireless. “This level of LBS accuracy will create an improved user experience for wireless customers, which ultimately generates additional revenue streams for carriers and other enterprises offering LBS applications.”


Polaris WLS™ is a patent-protected implementation of RF Pattern Matching, which provides the best network-based location performance in urban and indoor settings and is a perfect complement to A-GPS, enabling a best-in-class hybrid solution. Polaris’ WLS™ works without the RF Pattern Matching definition in standards, but standardization through 3GPP allows for future performance enhancements and provides flexibility for the solution and carrier implementations. Polaris’s current WLS products will continue to operate within existing standards.


By being included in the 3G UMTS standard, Polaris’ location technology has received further validation as one of the most accurate in the world. Polaris will now be considered a preferred provider to Tier 1 carriers and infrastructure vendors who want to add a high accuracy location solution to their technology mix that meets the new 3GPP standard.


The FCC is currently considering new E911 Phase II regulations that would improve indoor location capabilities for first responders. Using RF Pattern Matching, Polaris’ WLS™ software solution enables carriers and OEMs to be prepared to meet these new FCC requirements with little or no investment in new infrastructure or hardware.

RF Pattern Matching Discussion document presented in 3GPP is embedded below:


Friday, 10 September 2010

Selected IP Traffic Offload (SIPTO)

The industry is developing a new standard called Selected IP Traffic Offload (SIPTO). SIPTO allows internet traffic to flow from the femtocell directly to the internet, bypassing the operator’s core network, as shown in Figure 8 below.


More information on LIPA and SIPTO can be obtained from:
1. 3GPP TR 23.829: Local IP Access and Selected IP Traffic Offload (http://www.3gpp1.eu/ftp/Specs/archive/23_series/23.829/)

Thursday, 25 March 2010

Home Relays for LTE-Advanced

If you look at the Home eNodeB (Femtocell) architecture, the HeNB is connected to its gateway which in turn is connected to MME/S-GW. There is a considerable amount of technology investment in this approach. The HeNB consists of complete protocol stack, the HeNB-GW is an expensive piece of equipment and there is lots of other things including the management software, etc.
Now in LTE-A, there is a concept of Relays which we have talked about. The Relays do not contain the complete stack (generally just L1 and L2). If capacity is not an issue but coverage, then we may be able to use Home Relays.

The backhaul for Femtocell is Internet whereas for Relay its generally the same Radio resources within the cell. I guess the main thing for Relay is the requirement of reasonably good channel (Line of sight maybe). Home Relays can use the Internet connection but rather than connection terminating in some kind of gateway, it can terminate at the actual eNB.

There are already many advanced antenna techniques that can handle the transmission and reception without much interference and maybe the SON algorithms may need some additional improvements.
The main thing is that if this technology becomes reality then it may cost less than $50 per Home relay and would become really a commonplace.

Thursday, 11 March 2010

HSPA+ to reach 168Mbps in Release-10


Just when we thought that we have squeezed every bit out of HSPA, a surprise waiting is the speeds of upto 168Mbps in the downlink. Going back to the 3G Americas report, there is a section in the end that details HSPA+ enhancements for Rel-10:

Rel-8 introduced dual-carrier HSDPA operation in the downlink while Rel-9 similarly introduced dual-carrier HSUPA operation in the uplink and also enhanced the dual-carrier HSDPA operation by combining it with MIMO.

Further enhanced multi-carrier HSDPA operation is being specified for Rel-10, where the base station will be able to schedule HSDPA transmissions over three or four carriers simultaneously to a single user with the carriers are spread over one or two frequency bands. Solutions specified in earlier releases can be reused to a large extent. The difference is that now it is possible to configure a UE with one primary serving cell and up to three secondary serving cells. As in earlier releases, the secondary serving cells can be activated and deactivated dynamically by the base station using so-called “HS-SCCH orders.” With MIMO transmission on all four carriers, the peak rate would be doubled to 168 Mbps compared to Rel-9 and for typical bursty traffic the average user throughput would also experience a substantial increase.

Remember, I posted a blog on data rates calculation? The maximum data rate in Release-8 HSDPA is 42Mbps. With Dual-carrier operation, this could be doubled to 84Mbps. As you can probably guess, with 4 carriers, this will become 168Mbps ;)

For people who are less technically inclined, can check this Ericsson presentation on HSPA+ data rates. For people who may become sleepless without some technical references can check this report from RAN WG#1 meeting#59. If you are not sure what RAN WG#1 is, check quick tutorial on 3GPP here.

Going back to the 3GPP report, section 5.4 lists the details of 4 carriers HSDPA. It would be interesting to see what happens in cases where initially there were 4 carriers but then in a particular spot it changed to 2 carriers, and vice-versa. People who have yet to work on LTE may not have to worry too much as HSPA is being future proofed against the threats of LTE and WiMAX.

Interestingly enough, HSPA+ offers a better and cleaner solution at the moment especially with regards to voice calls and handing over to GSM then LTE or WiMAX.

It wont come as a surprise if the HSPA+ camp are able to pull out some new tricks from their bag just in time for Release-11.

Friday, 12 February 2010

A quick Introduction to M2M Communications

Machine-to-Machine (M2M) communications is a healthy sector that' s expanding rapidly and generating significant revenues for mobile network operators (MNOs). Devices outnumber subscribers by an order of magnitude, but the term doesn' t do justice to the concept and the market it represents.

The following is from 3G Americas report on 3GPP standards and their evolution to 4G:

By leveraging connectivity, Machine-to-Machine (M2M) communication would enable machines to communicate directly with one another. In so doing, M2M communication has the potential to radically change the world around us and the way that we interact with machines.

In Rel-10, 3GPP is in the process of establishing requirements for 3GPP network system improvements that support Machine-Type Communications (MTC). The objective of this study is to identify 3GPP network enhancements required to support a large number of MTC devices in the network and to provide necessary network enablers for MTC communication service. Specifically, transport services for MTC as provided by the 3GPP system and the related optimizations are being considered as well as aspects needed to ensure that MTC devices and/or MTC servers and/or MTC applications do not cause network congestion or system overload. It is also important to enable network operators to offer MTC services at a low cost level, to match the expectations of mass market machine-type services and applications.

The 3GPP study on M2M communications has shown potential for M2M services beyond the current "premium M2M market segment." The example of applications for mass M2M services include machine type communications in smart power grid, smart metering, consumer products, health care, and so forth. The current mobile networks are optimally designed for Human-to-Human communications, but are less optimal for M2M applications.


A study item on M2M communications (3GPP TR 22.868) was completed in 2007; however, no subsequent normative specification has been published. For Rel-10 and beyond, 3GPP intends to take the results on network improvements from the study item forward into a specification phase and address the architectural impacts and security aspects to support MTC scenarios and applications. As such, 3GPP has defined a work item on Network Improvements for Machine-Type Communication (NIMTC). The following goals and objectives are described in the work item:

The goal of this work item is to:
• Provide network operators with lower operational costs when offering machine-type communication services
• Reduce the impact and effort of handling large machine-type communication groups
• Optimize network operations to minimize impact on device battery power usage
• Stimulate new machine-type communication applications by enabling operators to offer services tailored to machine-type communication requirements

The objectives of this work item include:
• Identify and specify general requirements for machine-type communications
• Identify service aspects where network improvements (compared to the current H2H oriented services) are needed to cater for the specific nature of machine-type communications
• Specify machine-type communication requirements for these service aspects where network improvements are needed for machine-type communication
• Address system architecture impacts to support machine-type communication scenarios and applications

A RAN study item to investigate the air interface enhancements for the benefit of M2M communication has also been recently approved. The study will be initiated in early 2010.

Further Reading: