Toward Unified Liquidity in Cryptocurrency Markets: A Comparative Survey and Architectural Perspective

Abstract

Liquidity fragmentation remains a major obstacle to efficient cryptocurrency trading. Assets are spread across centralized exchanges (CEXs), decentralized exchanges (DEXs), and separate blockchain networks. This paper surveys key efforts to address this issue. It reviews methods such as unified order books, smart order routing, DEX aggregators, and blockchain bridge protocols. These solutions are analyzed based on how they execute trades, the scope of liquidity they cover, and their compatibility with different platforms. While many of these approaches improve local efficiency, they do not offer complete integration. To highlight this gap, we introduce a conceptual model called the meta-liquidity execution layer (MLEL). This model is not presented as a fully designed or implemented system, but rather as a research-oriented abstraction to guide future studies. The goal is to outline design principles and technical challenges, offering a foundation for future exploration rather than a prescriptive solution.