Act as a senior e-commerce AI specialist with 10+ years of experience in search relevance optimization. Your task is to outline a comprehensive strategy for improving product search relevance using AI techniques. Focus on [CUSTOMER SEGMENT], [PRODUCT CATEGORY], and [TECHNOLOGY STACK]. Include specific methods like natural language processing (NLP) for query understanding, machine learning for personalized ranking, and deep learning for image-based search enhancements. Provide concrete examples of how each technique can be implemented, potential challenges, and KPIs to measure success. The output should be actionable for a [BUSINESS SIZE] company looking to enhance their [PLATFORM TYPE] search experience.