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Showing posts with label TCP/IP. Show all posts
Showing posts with label TCP/IP. Show all posts

Sunday, 23 March 2014

Securing the backhaul with the help of LTE Security Gateway


An excellent presentation from the LTE World Summit last year, that is embedded below. The slide(s) that caught my attention was the overhead involved when using the different protocols. As can be seen in the picture above, the Ethernet MTU is 1500 bytes but after removing all the overheads, 1320 bytes are left for data. In case you were wondering, MTU stands for 'maximum transmission unit' and is the largest size packet or frame, specified in octets (8-bit bytes), that can be sent in a packet or frame based network such as the Internet.

Anyway, the presentation is embedded below:


Wednesday, 27 February 2013

Wi-Fi & Packet Core (EPC) Integration

Yesterday I wrote a blog post on whether Wi-Fi is the third RAN in the Metrocells blog. Today I am posting this excellent presentation that details how this Wi-Fi integration with EPC will be done.



Tuesday, 24 April 2012

LTE and IPv6

A discussion on Linkedin prompted me to add some relevant documents relating to LTE and IPv6. Interesting presentation below by Cisco:
Designing LTE with IPv6
View more presentations from Zahid Ghadialy. Available to download from slideshare here.

There are some other interesting presentations on slideshare you may want to look at:



Tuesday, 25 January 2011

MAPCON - Multi Access PDN Connectivity

On Monday, I read Bernard Herscovich, CEO, BelAir Networks saying the following in RCR Wireless:

Wi-Fi is obviously a way to offload data to alleviate congestion, but it also contributes to overall network profitability by delivering data at a lower cost per megabit that traditional macrocells. ABI Research estimates that carrier Wi-Fi can deliver data at 5% the cost of adding cellular capacity. Perhaps the most important driver, though, is the fact that, properly designed and architected, a carrier Wi-Fi network will deliver a consistently great user experience. The implications of that on attracting and retaining subscribers are obvious.

We've also seen cable operators taking advantage of their broadband HFC infrastructure to mount Wi-Fi APs throughout their coverage areas, offering free Wi-Fi as a sticky service to attract and retain home broadband subscribers.

At the GSMA Mobile Asia Congress, back in mid-November, 2010, KDDI's president and chairman explained that while they would be migrating to LTE, which would double their network capacity, data demand in Japan was forecast to increase by 15 times over the next five years. So LTE alone, he admitted, would not be enough. A few weeks before that, European operators, including Deutsche Telekom and Telefonica, were making similar statements at the Broadband World Forum in Paris.

It is clear that LTE alone will not be sufficient to meet ongoing mobile data demand. Technical innovation has resulted in huge capacity gains, but we're now at a point where additional bandwidth is more of a by-product of incremental spectrum. And, we all realize the finite nature of that resource. So, based on this new spectrum, LTE macrocells could deliver a 2 – 4X capacity increase. Meanwhile, ABI estimates that data capacity requirements are increasing 150% per year.

So, it's pretty clear that carriers are going to need more than just an LTE swap out to keep delivering a great user experience. They need to, as many already realize, augment their licensed spectrum with Wi-Fi. KT, the second largest mobile carrier in South Korea, claims to be offloading 67% of their mobile data traffic onto Wi-Fi. There may also be additional unlicensed spectrum made available, at least in the U.S. and the U.K., through the release of so-called white space spectrum, freed up through the switch from analog to digital TV.

It is obvious from the technology point of view that Multiple PDN connections would need to be supported when the UE is using LTE for part of data connection and Wi-Fi for other part. In fact these two (or multiple) connections should be under the control of the same EPC core that can help support seamless mobility once you move out of the WiFi hotspot.

One of the items in 3GPP Release-10 is to do with supporting of multiple Packet Data Networks (PDN) connections for a device. A Release-9 network and the UE can only support 3GPP access based connection via EPC. In Release-10 support for upto 1 non-3GPP access has been added.

FMC100044 specifies the following requirements:

  • The Evolved Packet System supports the following scenarios: a single Operator offering both fixed and mobile access; different Operators collaborating to deliver services across both networks.
  • The Evolved Packet System shall support the access of services from mobile network through fixed access network via interworking.
  • The Evolved Packet System shall be able to support functions for connectivity, subscriber authentication, accounting, Policy Control and quality of service for interworking between the fixed broadband access and Evolved Packet Core.
  • The Evolved Packet System shall optimize QoS and Policy management meaning that it shall offer minimal signalling overhead, while interworking between the fixed broadband access and Evolved Packet Core.
  • The Evolved Packet System shall be able to provide an equivalent experience to users consuming services via different accesses.

The Rel-10 work item extends Rel-9 EPC to allow a UE equipped with multiple network interfaces to establish multiple PDN connections to different APNs via different access systems. The enhancements enable:

  • Establishment of PDN connections to different APNs over multiple accesses. A UE opens a new PDN connection on an access that was previously unused or on one of the accesses it is already simultaneously connected to.
  • Selective transfer of PDN connections between accesses. Upon inter-system handover a UE transfers only a subset of the active PDN connections from the source to the target access, with the restriction that multiple PDN connections to the same APN shall be kept in one access.
  • Transfer of all PDN connections out of a certain access system. A UE that is simultaneously connected to multiple access systems moves all the active PDN connections from the source to target access, e.g. in case the UE goes out of the coverage of the source access.

This work also provides mechanisms enabling operator's control on routing of active PDN connections across available accesses.

The scope of the work is restricted to scenarios where the UE is simultaneously connected to one 3GPP access and one, and only one, non-3GPP access. The non-3GPP access can be either trusted or untrusted.

The design of the required extensions to Rel-9 EPC is based on TR 23.861 Annex A, that provides an overview of the changes that are expected in TS 23.401 and TS 23.402 for the UE to simultaneously connect to different PDNs via different access systems.

See Also:

3GPP TR 23.861: Multi access PDN connectivity and IP flow mobility

3GPP TS 22.278: Service requirements for the Evolved Packet System (EPS)

Old Blog post on Multiple PDN Connectivity

Thursday, 16 December 2010

Packet Flow in 2.5G, 3G, 3.5G and 4G




The 'LTE Signaling' is a very interesting book just being released that is a must have for people who are involved in design, development and testing. A book that explains the basic concepts from beginning till advanced concepts and explains how different components and interfaces fit together.

Though I havent yet read this book, I have read the earlier one titled UMTS Signaling, from the same authors that is an excellent reference for understanding Signalling in UMTS. I have no doubt that this book will be the same high quality.

The Excerpt on Wiley's website provides complete chapter 1 which is quite detailed and the Packet flow pictures and details below is extracted from this book.
The first stage of the General Packet Radio Service (GPRS), that is often referred to as the 2.5G network, was deployed in live networks starting after the year 2000. It was basically a system that offered a model of how radio resources (in this case, GSM time slots) that had not been used by Circuit Switched (CS) voice calls could be used for data transmission and, hence, profitability of the network could be enhanced. At the beginning there was no pre-emption for PS (Packet Switched) services, which meant that the packet data needed to wait to be transmitted until CS calls had been finished.

In contrast to the GSM CS calls that had a Dedicated Traffic Channel (DTCH) assigned on the radio interface, the PS data had no access to dedicated radio resources and PS signaling, and the payload was transmitted in unidirectional Temporary Block Flows (TBFs) as shown in Figure 1.2.

In Release 99, when a PDP (Packet Data Protocol) context is activated the UE is ordered by the RNC (Radio Network Controller) to enter the Radio Resource Control (RRC) CELL_DCH state. Dedicated resources are assigned by the Serving Radio Network Controller (SRNC): these are the dedicated physical channels established on the radio interface. Those channels are used for transmission of both IP payload and RRC signaling – see Figure 1.7. RRC signaling includes the exchange of Non-Access Stratum (NAS) messages between the UE and SGSN.

The spreading factor of the radio bearer (as the combination of several physical transport resources on the Air and Iub interfaces is called) depends on the expected UL/DL IP throughput. The expected data transfer rate can be found in the RANAP (Radio Access Network Application Part) part of the Radio Access Bearer (RAB) assignment request message that is used to establish the Iu bearer, a GPRS Tunneling Protocol (GTP) tunnel for transmission of a IP payload on the IuPS interface between SRNC and SGSN. While the spreading factor controls the bandwidth of the radio connection, a sophisticated power control algorithm guarantees the necessary quality of the radio transmission. For instance, this power control ensures that the number of retransmitted frames does not exceed a certain critical threshold.

Activation of PDP context results also in the establishment of another GTP tunnel on the Gn interface between SGSN and GGSN. In contrast to IuPS, where tunnel management is a task of RANAP, on the Gn interface – as in (E)GPRS – the GPRS Tunneling Protocol – Control (GTP-C) is responsible for context (or tunnel) activation, modification, and deletion.

However, in Release 99 the maximum possible bit rate is still limited to 384 kbps for a single connection and, more dramatically, the number of users per cell that can be served by this highest possible bit rate is very limited (only four simultaneous 384 kbps connections per cell are possible on the DL due to the shortness of DL spreading codes).

To increase the maximum possible bit rate per cell as well as for the individual user, HSPA was defined in Releases 5 and 6 of 3GPP.

In High-Speed Downlink Packet Access (HSDPA) the High-Speed Downlink Shared Channel (HSDSCH) which bundles several High-Speed Physical Downlink Shared Channels (HS-PDSCHs) is used by several UEs simultaneously – that is why it is called a shared channel.

A single UE using HSDPA works in the RRC CELL_DCH state. For DL payload transport the HSDSCH is used, that is, mapped onto the HS-PDSCH. The UL IP payload is still transferred using a dedicated physical data channel (and appropriate Iub transport bearer); in addition, the RRC signaling is exchanged between the UE and RNC using the dedicated channels – see Figure 1.8.

All these channels have to be set up and (re)configured during the call. In all these cases both parties of the radio connection, cell and UE, have to be informed about the required changes. While communication between NodeB (cell) and CRNC (Controlling Radio NetworkController) uses NBAP (Node B Application Part), the connection between the UE and SRNC (physically the same RNC unit, but different protocol entity) uses the RRC protocol.

The big advantage of using a shared channel is higher efficiency in the usage of available radio resources. There is no limitation due to the availability of codes and the individual data rate assigned to a UE can be adjusted quicker to the real needs. The only limitation is the availability of processing resources (represented by channel card elements) and buffer memory in the base station.

From the user plane QoS perspective the two major targets of LTE are:
• a further increase in the available bandwidth and maximum data rate per cell as well as for the individual subscriber;
• reducing the delays and interruptions in user data transfer to a minimum.

These are the reasons why LTE has an always-on concept in which the radio bearer is set up immediately when a subscriber is attached to the network. And all radio resources provided to subscribers by the E-UTRAN are shared resources, as shown in Figure 1.9. Here it is illustrated that the IP payload as well as RRC and NAS signaling are transmitted on the radio interfaces using unidirectional shared channels, the UL-SCH and the Downlink Shared Channel (DL-SCH). The payload part of this radio connection is called the radio bearer. The radio bearer is the bidirectional point-to-point connection for the user plane between the UE and eNodeB (eNB). The RAB is the user plane connection between the UE and the Serving Gateway (S-GW) and the S5 bearer is the user plane connection between the S-GW and public data network gateway (PDN-GW).

The end-to-end connection between the UE and PDN-GW, that is, the gateway to the IP world outside the operator’s network, is called a PDN connection in the E-UTRAN standard documents and a session in the core network standards. Regardless, the main characteristic of this PDN connection is that the IP payload is transparently tunneled through the core and the radio access network.

To control the tunnels and radio resources a set of control plane connections runs in parallel with the payload transport. On the radio interface RRC and NAS signaling messages are transmitted using the same shared channels and the same RLC transport layer that is used to transport the IP payload.

RRC signaling terminates in the eNB (different from 3G UTRAN where RRC was transparently routed by NodeB to the RNC). The NAS signaling information is – as in 3G UTRAN – simply forwarded to the Mobility Management Entity (MME) and/or UE by the eNB.

You can read in detail about all these things and much more from the Wiley's website here.

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

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, 9 September 2010

Local IP Access (LIPA) for Femtocells

I blogged about data offload earlier, for Femtocells. This traffic offload can be done via a feature called Local IP Access (LIPA). If you have LIPA support in your Home NodeB (HNB) or Home eNodeB (HeNB) then once you have camped on your Femtocell then you can access your local network as well as the network's IP network.

This would mean that you can directly print from your mobile to the local printer or access other PC's on your LAN. Note that I am also referring to access via Dongle as Mobile access though in practice I dont see much point of people just using dongles when they are in their Home Zone. Every laptop/notebook/netbook is now Wifi enabled so this situation doesnt benefit much for the dongle access.

I am sure there are quite a few unresolved issues with regards to the Security of the data, the IP address allocation, QoS, etc.

Continuous computing have a white paper on LIPA available that can be obtained by registering here. Anyway, enough information is available even without getting the PDF.

There is also a small presentation here that gives a bit of idea on LIPA.
As usual any comments, insights and references welcome.

Wednesday, 23 June 2010

'Internet Kill' switch and IPv9

Slightly off topic today as I was going through the pile of information and I caught attention of this news article that for some reason has not been reported by major newspapers. The article says that the president of USA will have the 'Kill' switch to kill off internet (temporarily i guess) in case of a major emergency like war, etc. Joseph Liberman who proposed this idea has since then backed away saying that he meant that parts of Internet can be disconnected like they do in China.

This brought into attention the other article I was going through about IPv9. Yes thats correct, I did write IPv9. I first heard about IPv9 back in 2004-5 but then it was dismissed as nothing serious. Apparently Chinese government backed Ministry of Information Industry (MII) has been promoting this IPv9. According to an old TelecomAsia.net article:

Back in July 2004, reports of a Chinese IPv9 prompted a bewildered reaction from internet godfather Vint Cerf. 'What could this possibly be about‾ As far as I know, IANA [Internet Assigned Numbers Authority] has not allocated the IPv9 designation to anyone. IPv9 is not an Internet standard. Could you please explain what is intended here‾" he wrote in an email to China's internet leaders.

The idea was dismissed as a "rogue" project with no official backing. But it is back on the table led, now as then by Xie Jianping, the head of the Shanghai Universal Institute of Chemical Technology and more recently in charge of the decimal network standards team in the MII's science and technology department.

The project returned to prominence at a press conference at the unusual location of the Party Central School in Beijing two weeks ago, where Xie announced that the networking technology had been successfully tested by China Netcom and the Ministry of Commerce.

He asserted that the project is all about China wresting control of its own IP networks away from US dominance for which, he claimed, China was paying 500 billion yuan a year.

The system reportedly uses numerical addressing to make China "the only country able to unify domain names, IP addresses and MAC addresses" into a single, metric system, according to Xinhua. Without any explanation, Xinhua said it also made China the only country outside the US "to have root servers and IP address hardware connectivity servers and its own domain name, IP address and MAC address resources".

In an interview with a skeptical Sina reporter, Xie and denied the project was another Hanxin - a reference to a fraudulent state-backed chip project.

"Our IPv9 has gone through testing and assessment," he said adding that he could not give any more detail but would "make public some material at the necessary time."

But the system, or what little is known of it, has plenty of doubters at home. Sina said critics of the system complain that turning domain names and brand names into numerals is a "backwards step" for the net.

The fact that the decimal network appears to asset control over root servers is bound to alarm internet governance bodies around the world.

And whatever else might be said about it, the project is clearly backed by the MII. "IPv9" raises more questions than answers.

So it looks like the Chinese government may have been expecting some 'Kill Switch' in the future by the US government and is probably creating a backup based on a new approach so that the users within China remain connected to their Internet.

Any thoughts and opinions are more than welcome...

Sunday, 13 June 2010

MBMS, Digital TV and IP Triple Play in China

Apparently according to this report by Xuefei (Michael) Peng, MBMS is alive and kicking in China with around 200,000 users already. I cant find more info so if anybody who can fill more info is more than welcome.

The government of mainland China has formulated a general plan to launch triple-play services, integrating telecom networks, broadcast and TV networks, and Internet together.

From 2010 to 2012, China will focus on the trial integration of broadcast and TV services and telecom services (including Internet services), dealing with any related policies. From 2013 to 2015, based on the trial experience, China will promote the integration nationwide.

In the coming five years, various sectors will prepare in different ways to meet the goals stated in the general plan. Telecom operators such as China Mobile, China Unicom, and China Telecom will invest more to promote IPTV services and accelerate FTTX deployment. Meanwhile, broadcast and TV operators will accelerate cable-TV network integration and interactive TV services development and will more actively develop value-added Internet services.

Broadcast and TV operators are currently strong in video content and wireless broadcast, while telecom operators own two-way fixed-line networks, mobile networks, and Internet services.

The differences between broadcast and TV operators across different regions and the uneven distribution of telecom fixed-line networks and mobile networks can offer cooperation opportunities.

Notably, almost all provinces of China already have launched IPTV services. The total number of IPTV service users in China has exceeded 5 million. However, problems with IPTV content must be solved, and the price for IPTV services also needs to be lowered to attract more users and compete with digital TV.

Meanwhile, the transformation of cable-TV networks from one way to two way has been sped up. Two-way cable-TV networks now cover over 24 million users. In the coming three years, broadcast and TV operators will invest over US$5 billion to continue to change 100 million one-way cable-TV links into two-way cable TV.

Eventually, through cable-TV networks, broadcast and TV operators hope to run Internet access services. This has been in trial use in some provinces. In order to run Internet access services, however, broadcast and TV operators need to rent bandwidth from telecom operators, greatly increasing the potential cost of service.

Another aspect of the triple play involves the conversion of mobile services to triple play. Mobile-phone TV is an emerging service in China. Up to now, mobile-phone TV services based on the China Multimedia Mobile Broadcasting (CMMB) standard have reached 1.5 million users. However, the current CMMB standard only supports one-way communication. So the users can only receive broadcast-TV programs via mobile.

On the other hand, mobile services based on the broadcast multicast Multimedia Broadcast Multicast Service (MBMS) standard serve about 200,000 users. The growing 3G user base will convert to the MBMS standard. Additionally, the government policy will affect the mobile-phone TV market too. So it is not clear yet which mobile-phone TV standard will dominate the industry in the future.

Thursday, 3 June 2010

Quick preview of 3GPP Release-11 Features and Study items


Release 11 Features

Advanced IP Interconnection of Services

The objective is to specify the technical requirements for carrier grade inter-operator IP Interconnection of Services for the support of Multimedia services provided by IMS and for legacy voice PTSN/PLMN services transported over IP infrastructure (e.g. VoIP). These technical requirements should cover the new interconnect models developed by GSMA (i.e. the IPX interconnect model) and take into account interconnect models between national operators (including transit functionality) and peering based business trunking. Any new requirements identified should not overlap with requirements already defined by other bodies (e.g. GSMA, ETSI TISPAN). Specifically the work will cover:

• Service level aspects for direct IP inter-connection between Operators, service level aspects for national transit IP interconnect and service level aspects for next generation corporate network IP interconnect (peer-to-peer business trunking).
• Service layer aspects for interconnection of voice services (e.g. toll-free, premium rate and emergency calls).
• Service level aspects for IP Interconnection (service control and user plane aspects) between Operators and 3rd party Application Providers.

To ensure that requirements are identified for the Stage 2 & 3 work to identify relevant existing specifications, initiate enhancements and the development of the new specifications as necessary.


Release 11 Studies

Study on IMS based Peer-to-Peer Content Distribution Services

The objectives are to study IMS based content distribution services with the following aspects:

- Identifying the user cases to describe how users, operators and service providers will benefit by using/deploying IMS based content distribution services. such as with the improvement of Peer-to-Peer technology. The following shall be considered:
- Mobile access only (e.g. UTRAN, E-UTRAN, I-WLAN);
- Fixed access only (e.g. xDSL, LAN);- Fixed and mobile convergence scenarios;
- Identifying service aspects where IMS network improvements are needed to cater for content distributed services for above accesses;
- Evaluating possible impacts and improvements on network when IMS based content distribution services are deployed;
- Identifying QoS, mobility, charging and security related requirements in the case of content distribution services on IMS;
- Identifying potential copyright issues;


Study on Non Voice Emergency Services

The Non Voice Emergency Services could support the following examples of non-verbal communications to an emergency services network:

1. Text messages from citizen to emergency services
2. Session based and session-less instant messaging type sessions with emergency services
3. Multi-media (e.g., pictures, video clips) transfer to emergency services either during or after other communications with emergency services.
4. Real-time video session with emergency services

In addition to support the general public, this capability would facilitate emergency communications to emergency services by individuals with special needs (e.g., hearing impaired citizens).

The objectives of this study include the following questions for Non Voice Emergency Services with media other than or in addition to voice:

1. What are the requirements for Non Voice Emergency Services?
2. What are the security, reliability, and priority handling requirements for Non Voice Emergency Services?
3. How is the appropriate recipient emergency services system (e.g., PSAP) determined?
4. Are there any implications due to roaming?
5. Are there any implications to hand-over between access networks
6. Are there any implications due to the subscriber crossing a PSAP boundary during Non Voice Emergency Services communications (e.g., subsequent text messages should go to the same PSAP)?
7. Do multiple communication streams (e.g., voice, text, video emergency services) need to be associated together?
8. What types of “call-back” capabilities are required?9. Investigate the load impact of Non Voice Emergency Services in the case of a large scale emergency event or malicious use.

Non Voice Emergency Services will be applicable to GPRS (GERAN, UTRAN) and to EPS (GERAN, UTRAN, E-UTRAN and non-3GPP).


Study on UICC/USIM enhancements

The intent of this study item is to identify use cases and requirements enabling Mobile Network Operators to distribute new services based on the USIM, to improve the customer experience and ease the portability and customisation of operator-owned and customer-owned settings from one device to another (such as APN and other 3G Notebook settings, graphical user interface, MNO brand, Connection Manager settings,…), and help in reducing operation costs and radio resources usage.


Objectives of this study item are:

-To identify use cases and requirements for new USIM
-based services taking into account the GSMA Smart SIM deliverables;
- To identify use cases and requirements for the USIM used inside terminals with specialised functionalities (e.g. radio modems, 3G Notebook terminals) taking into account the GSMA 3GNBK deliverables;
- To identify use cases and requirements to drive the evolution from the traditional USAT to a multimedia USIM toolkit support, with a particular aim to the Smart Card Web Server;


Study on Alternatives to E.164 for Machine-Type Communications

M2M demand is forecast to grow from 50M connections to over 200M by 2013. A large number of these services are today deployed over circuit-switched GSM architectures and require E.164 MSISDNs although such services do not require "dialable" numbers, and generally do not communicate with each other by human interaction.


Without technical alternative to using public numbering resources as addresses, and considering the current forecasts and pending applications for numbers made to numbering plan administration agencies, there is a significant risk that some national numbering/dialling plans will run out of numbers in the near future, which would impact not only these M2M services but also the GSM/UMTS service providers in general.


The Objective is to determine an alternative to identify individual devices and route messages between those devices. Requirements for this alternative include:

- Effectively identify addressing method to be used for end point devices
- Effectively route messaging between those devices
- Support multiple methods for delivering messages, as defined by 22.368
- Support land-based and wireless connectivity
- Make use of IP-based network architectures
- Addressing/identifiers must support mobility and roaming- support on high speed packet
-switched networks when available and on circuit-switched networks
- Consider if there are security issues associated with any alternatives

Tuesday, 25 May 2010

Quality of Service (QoS) and Deep Packet Inspection (DPI)

One of the things I mentioned in my presentation in the LTE World Summit was that differentiation of Services based on Quality of Services is required to be able to charge the users more.
This QoS can be varied based on deep inspection of the packets which can tell the operator as to what service a particular packet belongs to. The operators can thus give higher priority to the services and applications that are recommended by them and also block certain services that can be deemed as illegal or unproductive (like file sharing or P2P).

Continuous Computing claims to be one of the market leaders in producing the DPI systems. You can read this article by Mike Coward who is the CTO and Co-founder of Continuous computing here.

There is also this very interesting paper on QoS control in 3GPP EPS which is available freely here.

Please feel free to comment or suggest how do you see DPI being used in the future.

Friday, 19 March 2010

IPv6 transition in cellular networks gaining momentum


IPv6 is good and we all know that. I has been talked for years but practically it hasnt found much success. Verizon made some noise last year but I am not sure of the conclusion.

Just to recap, IPv4 was introduced back in 1982 and IPv6 work started since 1995. IPV4 uses 32 bit (4 bytes) addresses while IPV6 uses 128 bit (16 bytes) addresses. Theoretically we would now have 2^96 times more addresses than in case of IPv4.

Most of network infrastructure manufacturers have their equipment ready for IPv6 as some of the handset manufacturers. The main driver being that someday soon IPv4 addresses would be exhausted (Internet Assigned Numbers Authority will run out of IPv4 addresses in September of 2011, based on current projections) and their equipment would be ready to provide IPv6 addresses without any problems.

Recently, IETF-3GPP Workshop on IPv6 in cellular networks was held in San Francisco, USA on 1 - 2 March, 2010. There are lots of interesting presentations available here for people who want to dig a bit deeper. The concluding report that summarises the presentations and discussions are available here. Here is a brief summary from one of the reports (with links at the end):

Summary
  • Scenarios for IPv6 migration were discussed based on 3GPP Technical Report 23.975
    • The discussion focused on validating the scenarios
  • General IPv6 transition and deployment guidelines were outlined based on input from IETF
  • Solutions for migration and v4-v6 co-existence were presented
    • Solutions included existing RFCs and working group items but also proposals in Internet Drafts
    • Gap analysis wrt transition scenarios was discussed

Conclusions on scenarios
  • Scenarios 1 and 3 based on dual-stack and IPv6-only deployments were generally recognized as valid
  • Scenario 2 was also recognized as valid, addressing two separate problems related to insufficient RFC1918 space and subscriber identification
  • Scenario 4 did not receive wide support from the workshop, largely because it was felt that it addressed a problem already solved by other scenarios
  • Variants of some of these scenarios were brought up during the discussions, conclusions were not reached on these
    • These may need further discussion

Conclusions on solutions
  • It was recognized that necessary support in the network and devices is already available to “switch on” IPv6 in 3GPP networks
    • Some networks reported running dual stack
    • Some networks reported running IPv6-only now
  • Solutions enhancing existing mechanisms for dual stack deployments and new solutions for IPv6-only deployments drew wide support
    • Gateway-initiated Dual Stack Lite
    • Stateful IPv4/IPv6 translation
Next steps: 3GPP
  • IETF and 3GPP are expected to focus further work based on the conclusions of the workshop
    • Note that the workshop itself does not have the mandate to make formal decisions
  • 3GPP is expected to identify possible normative specification impacts, if any, of the preferred solutions
  • A need was identified to provide more operational guidelines about IPv6 deployment to 3GPP operators
    • The best location for these guidelines is FFS (e.g. 3GPP TR 23.975, GSMA, etc)
Next steps: IETF
  • IETF and 3GPP are expected to focus further work based on the conclusions of the workshop
    • Note that the workshop itself does not have the mandate to make formal decisions
  • IETF is encouraged to continue working on stateless and stateful IPv4/IPv6 translation mechanisms
    • These mechanisms are being worked on in IETF BEHAVE group
  • IETF is also encouraged to consider new solutions that are not yet working group items
    • Gateway Initiated DS Lite
    • Per-interface NAT44 bindings addressing IPv4 address shortage
  • Note that the workshop has not set any timelines

Further reading:

Friday, 6 November 2009

Inter-Layer Communication Primitives


IEEE defines service primitives that are used for communication between different layers in a protocol stack. There are 4 types of service primitives as can be seen in the diagram above and are described below:

Request: This is sent by the initiating side and from a higher layer to a lower layer. For example when RRC wants to send a message to peer RRC entity, it sends an RLC Data Request to RLC.

Indication: This primitive on the receiving entity is passed from Layer N to the layer above (N+1). For example when RLC entity receives MAC data from MAC and its addressed to RRC, it sends RLC Data Ind to the RRC.

Response: This is the response to the Indication on the receiving entity. So in our example case, RLC Data Resp would be sent by RRC when it receives RLC Data Ind.

Confirm: This is used as a reply in the sending entity as the lower layer conveys the result of one or more previous request primitives. The confirm will generally contain status code indicating success or failure of the procedure. In our example, RLC Data Cnf will be sent by RLC as a response to RLC Data Req.

Sunday, 14 June 2009

Verizon's bold step towards IPv6


Verizon is taking bold step of mandating the devices that connect to its LTE Network support IPv6. The following is from Telecom Asia via Network World:

According to device requirements Verizon released earlier this year, any device that hooks onto the LTE network currently being built on the 700MHz band "shall support IPv6" and further states that "the device shall be assigned an IPv6 address whenever it attaches to the LTE network." The requirements make support for IPv4 optional and state that any device supporting IPv4 "shall be able to support simultaneous IPv6 and IPv4 sessions."

IPv6 is a long-anticipated upgrade to the Internet's main communications protocol, which is known as IPv4.

As CircleID blogger and Pennsylvania State University senior systems programmer Derek Morr notes, the adoption of IPv6 is going to be particularly important for wireless carriers that are expecting a surge in mobile data traffic in the next few years, as they will need a fresh batch of Internet addresses to handle the multitude of wireless devices that will hook onto their networks.
"The problem, of course, is that we're running out of IPv4 addresses," Morr writes. "The IANA pool will most likely be depleted by the end of 2010. This has led many people to wonder if LTE deployments will require IPv6. Now we have an answer: Yes."

Verizon is planning to launch its LTE services commercially in 25 to 30 U.S. markets in 2010. The network will be the first mobile broadband network in the United States to be based on the LTE standard, which is the latest variation of Global Systems for Mobile Communications (GSM) technology that is used for 3G High-Speed Packet Access (HSPA) networks. AT&T and T-Mobile have also announced plans to commercially launch LTE networks after 2010, while Sprint has already commercially launched its high-speed mobile WiMAX network.

One of the biggest drivers for carriers upgrading their mobile data networks to 4G technologies is the expected explosion in demand for mobile video services. A recent Cisco study on Internet traffic trends projects that 64% of mobile data traffic will be for video by 2013, vs. 19% for data services, 10% for peer-to-peer and 7% for audio. The study also says that the projected video traffic will increase four-fold between now and 2012

You may also want to read my post on the case for early LTE in USA.

Wednesday, 25 March 2009

Difference between SDU and PDU

This question keeps propping up in many discussions so here is an explanation for the difference between PDU and SDU.



Going back to the basics, a protocol stack consists of many different individual protocols. Protocols can be simply described as set of rules that allow communication between peer entities or they can also be described as set of rules that facilitate horizontal communication. Now these protocols are arranged in layers as can be seen in the figure above. In the transmitter side, a layer N receives data from layer N+1 and this data is called the SDU or Service Data Unit. This layer will modify the data and convert it into a PDU or a Protocol Data Unit. The peer entity in the receiver is only able to understand this PDU.

In simplest form, this modification by layer N of the layer N+1 SDU contains encapsulation. In encapsulation, the SDU is preserved as it is and an additional header is added by the layer N protocol. The modification can also perform concatenation (where more than one SDU is combined in a single PDU), segmentation (where a SDU can be split so that different parts of it end up in different PDU) and padding (where SDU is so small that filler bits are added in the end to complete the PDU).

In the receiver side, the peer entity receives the PDU from layer N-1 (its actually layer N-1 SDU) and convert it back into SDU(s) and passes it to layer N+1.


The figure above shows an example of RLC SDU and PDU. The SDU's are received from higher layer, which is from PDCP in case of LTE. These SDU's have to be converted to PDU's so they undergo segmentation and concatenation and suitable RLC headers are added to form the RLC PDU's.

First Figure Source: The TCP/IP Guide

Second Figure Source: 3G Evolution - HSPA and LTE for Mobile Broadband, Erik Dahlman et al.