- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
More and more cellular network operators enable the unplanned deployment of small-sized cellular stations by the end users into the predominant macrocellular network layout. This increases the spatial capacity of the cellular system and reduces the costs for installing, managing, and operating the radio access network. However, the impact of such an unplanned network densification on the robustness of cell handover (HO) still remains unclear and needs to be studied. For this purpose, in this paper we highlight the key aspects of the cell HO process in the presence of small cells and identify the main issues that affect its robustness. We summarize lessons learned from the rich literature on HO decision algorithms for small cells, and present an algorithm for alleviating interference in the cellular uplink while prolonging the battery lifetime of the user terminal. Based on the evaluation methodology of the Small Cell Forum, we conduct a comprehensive system-level simulation study to validate the accuracy of our findings and provide valuable insights on the key performance trade-offs inherent to the HO decision for small cells.
We have overviewed the main open issues for cell HO in the presence of small cells, with emphasis on the implementation-dependent HO decision stage. We have re- viewed existing design approaches for HO decision in order to discuss lessons learned and practices for the algorithmic design of HO decision in small cell networks. Based on this discussion, we have proposed a HO decision algorithm that addresses most of the design guidelines under consideration. Using the Small Cell Forum evaluation methodology, we have validated our views on lessons learned for HO decision in the presence of small cells, and have revealed the key advan- tages and main weaknesses of existing design approaches. The simulation study has shown that the utilization of stan- dard LTE-A measurements allows the proposed algorithm to double the macrocell offloading gain, enhance the uplink ca- pacity (around 0.5 Mbps per user) and reduce the interfer- ence at the UEs (up to 7 dB). On the other hand, the intense utilization of the small cell infrastructure combined with the exchange of the standard LTE-A measurements have been shown to increase the cell interference (up to 8 dB) and the HO probability/signaling requirements. Our results highlight the need for small cell specific interference mitigation and novel cell HO protocols tailored to the specific characteristics of the small cell network.