Hybrid SONs offer bottom-line results for 3G as well as LTE

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Deploying hybrid self-organizing networks (SONs) can slash service provider capex and opex by at least 25 percent and, in the case of a large U.S. mobile operator, could save more than $3 billion over three years, according to a joint study released by vendor Aircom International and consultancy Analysys Mason.

The study also revealed that savings for a communications service provider (CSP) from the use of hybrid SONs can lead to EBITDA that is 5 percent larger than if SON features were not implemented.

Hybrid SONs combine the features of distributed SONs, in which SON algorithms are deployed locally in the base station/controller, and centralized SONs, in which algorithms are deployed above the network infrastructure. A hybrid SON is generally located in the operations and maintenance center (OMC) or a server sitting northbound of the OMC. "In a hybrid architecture, the manufacturer deploys distributed algorithms at the base stations and provides a set of open interfaces to allow the CSP to use a control algorithm that operates on a wider geographic area on a slower time scale," according to the study.

The savings uncovered by the study result from a number of hybrid SON benefits. For example, engineers might spend 50 percent of their time optimizing neighbor cell site relations, but if that chore is automated, the engineers can instead focus on larger problems that absolutely require human intervention, Steve Bowker, Aircom CTO, told FierceBroadbandWireless.

Minimizing the number of costly site visits is also an advantage. "If you put a remote electrical tilt on the antennas, there's obviously a capital outlay to do that, but once it's fitted, it reduces significantly the visits to the site," Bowker said.

Aircom and Analysys Mason were surprised to find that hybrid SONs could dramatically reduce energy costs. "Powering down certain aspects of a base station or taking them down to a standby state, that saves a significant amount of energy and prolongs the life of the equipment as well," Bowker said.

SONs can also help reduce churn by improving coverage and cutting the number of dropped calls, though Bowker said the study did not heavily weight that benefit because operators tend to be skeptical when churn improvements are touted.

The study, which did not include the impact of small cells such as picos and femtos on the considered scenarios, also revealed that hybrid SONs benefit WCDMA networks even more than LTE networks. The primary reason is that adding SON architecture to an existing 3G infrastructure will give an operator extra capacity, enabling it to defer upgrades or roll them out incrementally.

Mark Mortensen, principal analyst with Analysys Mason, said hybrid SONs also deliver significantly higher energy savings to WCDMA networks as opposed to LTE networks because 3G equipment tends to be more energy-inefficient by nature.

Despite the benefits promised by SON architecture, there can be significant drawbacks for an operator that is not technically up to the challenge of overseeing the technology. Bowker noted that some people suggest SON should stand for "self-oscillating networks" because they can get out of control if not closely managed.

Mortensen cautioned that issues could arise in the future when SONs automatically take actions based on certain policies, which may conflict with QoS and traffic management policies. "You end up with multiple systems here that are non-procedurally programmed," making network events difficult to predict, he said.

Operators will likely need to conduct considerable simulation work to ensure their SON deployments do not cause unintended consequences.

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