c++ typedef/type substitution for enumeration class

As far as I am aware at the moment it is not possible to do a typedef of the C++11 enum class. I would like to know if there is any other way I can reduce the length of the name of an enum variable when referring to it outside of the encapsulating class. Here is an example:

// I would like to do something along the lines of:
class SegmentActivityState;
using SegmentActivityType = SegmentActivityState::ActivityStateType;

// ...However, this results in the compile time error:
// 'SegmentActivityState' does not name a type. 

// Enumeration class definition
class SegmentActivityState
{
public:
    enum class ActivityStateType : Index
    {
        PreExecution = 0,   /**< Pre-execution state. */
        Execution = 1, /**< Execution state. */
        PostExecution = 2 /**< Post-execution state. */
    };

private:
    ActivityStateType ActivityState;
    /**< unique object identifier tag. */

public:
    // ... Methods that work on the ActivityState
}

The most important issue is the length of the name by which I have to refer to the enum outside of SegmentActivityType. For example, in order to do a type comparison I need to write SegmentActivity.getState() == SegmentActivityState::ActivityStateType::PreExecution, which is very verbose. Two things that I do not want to do are:

1. Do a typedef on SegmentActivityState.
2. Move the enum class ActivityStateType outside of the class SegmentActivityState definition.