A symbiotic perspective on low-cost cellular and multihop WLAN interworking solutions

Interworking between wireless local area networks (WLANs) and cellular networks (such as 2G and 3G) is expected to break new ground for sophisticated business models. Omnipresent cellular networks have a well-defined infrastructure, but lack capability to provide broadband and/or real-time services (e.g., streaming video and gaming). Conversely, WLANs supports high data rates, while the infrastructure for service provision is vague. Therefore, the combination of the cellular core network infrastructure with its service centers and accounting capabilities with the achievable data rate of WLANs can provide the possibility of offering new services to the customer. This interworking is being considered in different standardization and operational activities. WLAN hotspots are already on the way, but the high installation costs of WLANs, especially for larger hotspots, are repressing a faster evolution. The installation costs are mainly driven by the cabling infrastructure. To reduce these costs and to gain flexibility, we advocate exploiting multihop capability for WLAN coverage extension by introducing the concept of virtual access points. However, the high data rates of WLAN solutions are hindered by the standard IEEE 802.11 MAC protocol, which has been shown to be inappropriate for multihop operation. In this article we consider an improved version of the IEEE 802.11 MAC that involves only minor changes to the existing standard, which allows for a faster deployment and the usability of the approach in existing interworking scenarios. The specific contribution of this article is a thorough exploration, by means of simulation, of the performance of such an approach. In particular, we demonstrate that the enhanced MAC is capable of offering high data rates in multihop WLAN extensions to the cellular network. Besides the networking structure, a pertinent issue in the WLAN cellular symbiosis is security. In this respect we discuss multihop operation in light of current interworking (security) activities.