Planning Future Heterogeneous Wireless Networks

In this paper, based on the analyzed emerging challenges encountered by the future radio network, we focus on several candidate techniques targeting at a more spectrum-efficient and cost-effective solution. Among them, spectrum management is one special topic covering fields of technique, regulation and politics. We point out the high tendency of spectrum liberation in terms of spectrum allocation for services and radio technologies even between different network providers. In the network planning topic, we address a number of solutions w.r. t. some typical dominating factors. A solution reducing the risk of high expenditure in conjunction with the flexibility of spectrum management is also given. To further enhance the efficiency, advanced radio resource management allowing interworking among heterogeneous radio technologies is also presented. I. Introduction Furthering the big success of the GSM system (Global System forMobile communications) with the population of subscribers reaches over 250 million worldwide, the international mobile and wireless market turns out to the evolution of third Generation Mobile Communication System termed as the UMTS (Universal MobileT elecommunication System) and the system beyond it. Future radio network faces practical challenges such as the higher throughput and more elastic traffic demand based on the exploiting multimedia services, the scarcity and deployment difficulty, the heterogeneity of different radio air interface and the high cost of network deployment and operation. To achieve high spectrum efficiency with high coverage is always the goal to design a radio network. After the significant contribution from Shannon in the late 50’s, people research on radio transmission technology targeting at approaching the Shannon bounds for different scenarios like AWGN noise-limited channel, fading channel, multi-user communication environment, etc. Several technologies achieve significant improvement of spectrum efficiency, such as the advanced channel coding schemes, diversity approach, digital modulation schemes, joint source-channel coding schemes, accurate channel estimation and joint detection techniques, antenna techniques like MIMO (Multiple Input and Multiple Output), etc. From higher layer mechanism viewpoint, one can see the performance improvements given by a number of mechanisms like Medium Access Control P rotocol (MAC), Data Link Control P rotocols (DLC), Radio Link Control P rotocols (RLC) as well as Radio Resource Control P rotocols (RRC). In the network layer and beyond, mechanisms enhancing the performance for TCP (T ransport control protocol) and UDP (User Diagram protocol) over IP protocol are required for the wireless communication. From the system level, advanced network planning and management techniques are needed catering for the heterogeneity and therefore facilitating the interoperability of the co-existing Radio Access T echnologies (RATs). Apart from the cellular technologies, kinds of Broadband W ireless Access (BWA) technology have been emerged for years. Typical examples are the WLAN (W ireless Local Area Network) represented by IEEE 802.11 family, Hiperlan in Europe and WiMAX (W orldwide interoperability for Microwave Access) represented by IEEE 802.16 family. In order to offer ubiquitous wireless access, the interworking and harmonization among heterogeneous networks are considered as primary important in the coming years. One aspect of it is to design the wireless local network as a complementarity to the cellular radio network, which must be considered in the network planning phase for such heterogeneous networks. Different to the classical network planning scheme, network co-planning for heterogeneous networks is not only based on the carrier strength that the mobile terminals can receive, traffic distribution, networks’ deployment costs, their interoperability, and the terminal capabilities and spectrum management are tightly associated topics.