UMTS Network Interfaces and Protocol Stack

UMTS network follows the typical communication model in telecom which defines a set of horizontal and vertical layers. The horizontal layers are physical, network, transport and application layers – as defined in the OSI model. The vertical layers are functional areas, namely control plane, user plane and data plane. Control planes are used to control a link or a connection; user planes are used to transparently transmit user data from the higher layers. The UMTS network interfaces and protocol stacks follow the same communication model. Standard transmission issues, which are independent of UTRAN requirements, are applied in the horizontal transport network layer. The UTRAN requirements are addressed in the horizontal radio network layer across different types of control and user planes. The UMTS network introduces four new key interfaces and protocol stacks: Uu, Iub, Iur, and Iu.

Iu: Radio Access Network Application Part (RANAP) [3G TS 25.413]. This interface provides UTRAN–specific signaling and control over the Iu. The following is some typical RANAP functions:

• Overall radio access bearer (RAB) management, which includes the RAB’s setup, maintenance, and release
• Management of Iu connections
• Transport of nonaccess stratum (NAS) information between the UE and the CN; for example, NAS contains the mobility management signaling and broadcast information.
• Exchanging UE location information between the RNC and CN
• Paging requests from the CN to the UE
• Overload and general error situation handling

Iur: Radio Network Sublayer Application Part (RNSAP) [3G TS 25.423]. This interface provides UTRAN–specific signaling and control for the following sample functions:

• Management of radio links, physical links, and common transport channel resources
• Paging
• SRNC relocation
• Measurements of dedicated resources

Iub: Node B Application Part (NBAP) [3G TS 25.433]. This interface provides UTRAN specific signaling and control for the following sample areas:

• Management of common channels, common resources, and radio links
• Configuration management, such as cell configuration management
• Measurement handling and control
• Synchronization (TDD)
• Reporting of error situations

Uu: Radio Resource Control (RRC) [3G TS 25.331]. This interface handles the control plane signaling over the Uu between the UE and the UTRAN. Some of the functions offered by the RRC

include the following areas:

• Broadcasting information
• Management of connections between the UE and the UTRAN, which include their establishment, maintenance, and release
• Management of the radio bearers, which include their establishment, maintenance, release, and the corresponding connection mobility
• Ciphering control
• Outer loop power control
• Message integrity protection
• Timing advance in the TDD mode
• UE measurement report evaluation
• Paging and notifying

UTRAN Iu, Iub, Iur, Interfaces protocol stacks:

UTRAN Iu, Iub, Iur, Interfaces protocol stacks

Circuit Domain Mc, Nb, Nc interfaces protocol stacks:

Circuit Domain Mc, Nb, Nc interfaces protocol stacks

GSM Abis, A, C, D, E, F, H interfaces protocol stacks:

GSM Abis, A, C, D, E, F, H interfaces protocol stacks

GPRS Gb, Gn, Gp, Gs Interfaces protocol stacks:

GPRS Gb, Gn, Gp, Gs Interfaces protocol stacks

Location service La, Lb, Lp, Um, Uu interfaces protocol stacks:

Location service La, Lb, Lp, Um, Uu interfaces protocol stacks

A Look Back at A Year in the Life of the Clash of the Titans

2008 started out as the launch year for mass mobile WiMAX deployments that would capitalize on WiMAX’s prior meteoric rise in ecosystem development. During the year the rapid pace of component, device and systems developments and certifications continued to accelerate, but commercial deployments – particularly that expected from Clearwire – were delayed, slowing overall momentum at the onset of a worsening economic climate for greenfield and alternative operators. Meanwhile, the LTE effort gained momentum and ratcheted up the level of hype preceding finalization of the 3GPP standard and commercial deployments.

The theme of open source development and IP access clearly took hold of consumer markets The industry witnessed mind and market share gains of Apple’s iPhone, Google’s Android, and Yahoo! Go/Direct, which reshaped the mobile device services and Internet portal landscape. Mobile industry giants including Nokia, Ericsson, Motorola, Samsung and LG did not stand still: new rich software interface-based devices came to market that mimic iPhone’s salient features, while adding a few unique twists. It seems that every major player among mobile and web companies has now joined the gambit to become the next unified services provider.

We look back at a listing of 2008’s major events:

1. 700 MHz auction ends, incumbent wireless operators are the biggest winners: 700 MHz to be LTE heavy - AT&T Mobility, VZW announce LTE plans for the ‘beach front property’ spectrum
2. Sprint-Nextel reels from subscriber defections and resulting losses, stalling rollout momentum of Xohm WiMAX service.
3. Nokia and Qualcomm reach an IPR settlement: parties enter into IPR cross-licensing that extends to LTE and Qualcomm-Nokia chip and device collaboration.
4. Qualcomm drops UMB to focus on LTE, solidifies 3GPP and 3GPP2 efforts going forward.
5. China reorganized its telecommunications industry to consolidate and leverage TC-SCDMA efforts to support TDD-LTE, the TDD version of LTE-Advanced. Datang and Huawei are primary developers; China Mobile expected to see deployment in 2009-10.
6. The U.S. and world economy stumbled headlong into a deep recession precipitated by an unprecedented collapse in major financial institutions.
7. Packaged 3G data services and flat rate plans presage introduction of Clearwire.
8. WiMAX ICs and device development crosses the threshold of opportunity for mobile network adoption. Low power needed for mobile devices exceed market cycle expectations.
9. The formation of ‘New Clearwire’: joins efforts of Clearwire, Sprint, Comcast, Time Warner Cable, Brighthouse Networks, Google, and Intel Capital.
10. The LTE Licensing framework is formed to help orchestrate a licensing regimen for patents essential to LTE.
11. The Open Patent Alliance is formed to establish form a pool for patents essential to WIMAX.
12. Lawsuits by Intel and Adaptix over WiMAX IPR are initiated to test the orchestration of IPR licensing in next generation wireless.
13. Sprint Xohm WiMAX is officially launched in Philadelphia and additional cities are planned. Reviewers agree that performance exceeds but coverage lags.

14. HSPA and EVDO data subscriber growth surged. What’s more, bandwidth usage outpaced earlier expectations, particularly on the uplink side, pressuring network capacity including backhaul.
15. With the standard recently locked down and publication expected in the first quarter, Verizon eagerly announced its intent to deploy 3G-LTE during 2009.
16. LG announced demonstration of the first LTE handset modem IC, but does not expect production to start expected until 2010. Qualcomm had previously announced plans to have LTE plus HSPA and EVDO multi-mode chips by mid-2009.
17. President-elect Obama’s technology policy team indicates broadband access to be part of the expected economic stimulus and technology development program.
18. The IEEE announces collaboration with VIA Licensing Inc. to facilitate patents pools for all standards.
19. The FCC announces that the White Spaces spectrum decision will be punted to the next administration. Decisions on AWS-3 also are unlikely until next year.
20. Sprint announced availability of the U-300 WiMAX and EVDO modem in the Baltimore area, with broader availability to coincide with the launch of WiMAX. The 3G/4G connection plan is priced at $80 million.
21. Femtocell gains momentum among major operators: this extension of 3G may blunt the need for migration to LTE.
22. IPR and leading commercial developments show that 4G networks will be ‘smart’, self-configuring and highly granular.
23. Forecasts for communications sector growth are cut as credit tightens and consumer spending declines.
24. Patent applications and standards development activity appears unaffected by the turbulent economy; particularly, the pace of smart antenna and advanced wireless network segments continues to accelerate.

Upon reflection, we see that the past year has resulted in several watershed events and groundbreaking developments. Much has been afoot that foretells industry transformation that lies ahead. 2008 has neither been the year of WiMAX nor of LTE, but it has witnessed a chain of events that prepare the way for widespread adoption of next generation network evolution to 4G alongside existing mobile networks. Although the appetite of consumers may be partly hedged by economic doldrums, trends toward open services, and flat and flexible rate plans indicates room for growth of more efficient NG networks.

The delay of Sprint’s Xohm WiMAX has allowed development of devices to proceed closer to the sweet spot of low power and lower cost needed for embedded and mobile devices. The software and services community has also had more time to unfold environments suitable for the open mobile device and network business model. Perhaps if Xohm had rolled out aggressively during 2008 it would have met with startup problems that would have been open to ridicule.

Tier 1 suppliers and most incumbent operators have rallied around the LTE flag even as the ship remains in dry dock. Mobile operators have moved swiftly to migrate core networks to IP and host more open services and devices. This helps to prepare the way for the coming age of unified communications that melds IT/Networking and consumer electronics business models in a more compelling and disruptive manner than mere convergence within standards and technologies. On this front, we have seen confirmation of the forecast convergence of 802.16 and LTE, particularly for the ITU-Advanced version, which more fully aspires to be called 4G.