help with EntityFieldQuery


I downloaded a template, that is using EntityFieldQuery() to generate previous / next buttons on the detail view of the specific Content type. My problem is, that the prev/next buttons are showing all nodes and not only the nodes of a specific category.
->entityCondition(‘entity_type’, ‘node’)
->propertyCondition(‘status’, 1)
->entityCondition(‘bundle’, $node->type);

How do I need to change the query, that it only gives me back the nodes, that have the same category_type of the selected node. The field with the stored info of my custom content type is:
field_portfolio_category, Term reference.

Thanks for your help.

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