SON for reducing Opex in Legacy Networks

Presented by Stéphane Téral, Principal Analyst, Mobile and FMC Infrastructure, Infonetics Research in the 1st Self-Organizing Networks Conference, 30th Nov and 1st Dec. 2010 at the Waldorf Hilton.

SON Features in Legacy Networks

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When Femtocells become Picocells

Femtocells are not really becoming Picocells but when you read about the new features coming up in Femtocells, you can imagine why operators are embracing Femtocells.

A typical Picocell, offers limited coverage but the same capacity as a macro-cell and can cost between £5000 to £10000. A Femtocell overs very limited coverage and very few users but its dirt cheap.

What if a compromise Femtocell is made that can solve both the coverage/capacity and price then its a win win situation for everyone.

This is where "Metro Femtocells" come into picture. They can be called by different names but lets stick to Metro Femtos.

Ubiquisys's press release about the Colo-Node HSPA Femtocell shows us the direction in which the device manufacturers are moving. It allows 16 users (as opposed to 4) and the range of 2km (as opposed to couple 100 metres). Picochip has already released a chip that can serve 32 users at 2km range. These femto's are Release-7 compliant with 42Mbps peak dl and and 11Mbps peak ul.

The good thing is that they may be soon used to fill the coverage black holes but that can also mean that the operators may stop putting lot of effort in Network optimisations.

The ubiquisys Colo-Node HSPA will be available end of July this year.

Ubiquisys has also demonstrated a wide area femtocell with 12 sq. km range. I wonder where they will be used.

Self Organizing Networks and Enhancements

I have blogged about SON earlier here and here. The following is an update from the 3G Americas Whitepaper on Mobile Broadband:

SON concepts are included in the LTE (E-UTRAN) standards starting from the first release of the technology (Rel-8) and expand in scope with subsequent releases. A key goal of 3GPP standardization is the support of SON features in multi-vendor network environments. 3GPP has defined a set of LTE SON use cases and associated SON functions. The standardized SON features effectively track the expected LTE network evolution stages as a function of time. With the first commercial networks expected to launch in 2010, the initial focus of Rel-8 has been functionality associated with initial equipment installation and integration.

The scope of the first release of SON (Rel-8) includes the following 3GPP functions, covering different aspects of the eNodeB self-configuration use case:

• Automatic Inventory

• Automatic Software Download

• Automatic Neighbor Relations

• Automatic PCI Assignment

The next release of SON, as standardized in Rel-9, will provide SON functionality addressing more maturing networks. It includes the following additional use cases:

• Coverage & Capacity Optimization

• Mobility optimization

• RACH optimization

• Load balancing optimization

Other SON-related aspects that are being discussed in the framework of Rel-9 include improvement on the telecom management system to increase energy savings, a new OAM interface to control home eNodeBs, UE reporting functionality to minimize the amount of drive tests, studies on self testing and self-healing functions and minimization of drive testing. It should be clarified that SON-related functionality will continue to expand through the subsequent releases of the LTE standard.

The SON specifications have been built over the existing 3GPP network management architecture, reusing much functionality that existed prior to Rel-8. These management interfaces are being defined in a generic manner to leave room for innovation on different vendor implementations. More information on the SON capabilities in 3GPP can be found in 3G Americas’ December 2009 white paper, The Benefits of SON in LTE.

SON technologies have been introduced in Rel-8/Rel-9 to help decrease the CAPEX and OPEX of the system. LTE-Advanced further enhances the SON with the following features:

• Coverage and Capacity Optimization. Coverage and Capacity Optimization techniques are currently under study in 3GPP and will provide continuous coverage and optimal capacity of the network. The performance of the network can be obtained via key measurement data and adjustments can then be made to improve the network performance. For instance, call drop rates will give an initial indication of the areas within the network that have insufficient coverage and traffic counters can be used to identify capacity problems. Based on these measurements, the network can optimize the performance by trading off capacity and coverage.
• Mobility Robustness Optimization. Mobility Robustness Optimization aims at reducing the number of hand over related radio link failures by optimally setting the hand over parameters. A secondary objective is to avoid the ping-pong effect or prolonged connection to a non-optimal cell.
• Mobility Load Balancing. Related to Mobility Robustness is Mobility Load Balancing, which aims to optimize the cell reselection and handover parameters to deal with unequal traffic loads. The goal of the study is to achieve this while minimizing the number of handovers and redirections needed to achieve the load balancing.
• RACH Optimization. To improve the access to the system, RACH Optimization has been proposed to optimize the system parameters based upon monitoring the network conditions, such as RACH load and the uplink interference. The goal is to minimize the access delays for all the UEs in the system and the RACH load.

In addition to the enhanced SON technologies described above, minimization of manual drive testing functionality is also currently under examination in 3GPP to enhance and minimize the effort for optimization of the LTE-Advance network. The main goal is to automate the collection of UE measurement data. In so doing, it will minimize the need for operators to rely on manual drive tests to optimize the network. In general, a UE that is experiencing issues, such as lack of coverage, traffic that is unevenly distributed or low user throughput, will automatically feed back measurement data to the network which may be used by the network as a foundation for network optimization.

SON related 3GPP references can be found on Martin Sauter's blog here.

3G & LTE: What Lies Ahead for Performance Management?

Long but Interesting presentation (with audio) for Technically minded people.

3G & Beyond: What Lies Ahead for Performance Management?

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