| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 102 === Long Term Evolution (LTE) is a standard for wireless mobile network from The 3rd Generation Partnership Project Agreement (3GPP). Long Term Evolution–Advanced (LTE-A) is evolutionary version from LTE. LTE-A add some new technologies, one of which is Heterogeneous networks (HetNets). HetNets can build Pico eNB (eNodeB), Femto eNB and Relay whose transmission power is less than Macro eNB in Macro network to improve the communication quality on cell edge or hot spot users. However, when different kind of eNB transmit signals to their UEs (User Equipment) using same frequency at the same time, and two of UEs are in each other's transmission signal range, that will cause Co-channel Interference to make two of UEs can’t accurately receive the transmitted signals from their service eNB.
LTE TDD system specification seven kinds of uplink and downlink configuration, but failed to say how you can efficiently use the seven kinds of configurations. And LTE interference between cells exist in, especially in the TDD system is more important to note the presence of the frame interlace interference. When a different frame interlace interference ratio of the vertical line of the groove is configured by the two adjacent regions of the TDD system used in a portion of the time there will be "during a downlink transmission system, the other system uplink transmission frame interleaved into the interference ", so in a heterogeneous network, the dynamic between the base station using a different proportion of uplink and downlink configuration problem to cause Crossed Timeslot Interference, resulting in a decrease in the transmission data rate of the phenomenon.
In order to solve the above problems, this paper proposes four models to dynamically adjust the ratio method and the uplink and downlink slot configuration, considering the heterogeneous network environment, flexibility of use in the uplink and downlink slot configuration to increase the proportion of traffic system and make improvements for frame interleaving impact. The numerical results show that the performance evaluation of each project, this paper proposes a method to dynamically adjust the ratio of the uplink and downlink configuration to get better traffic and solve the existing TDD systems can be flexibly adjusted the uplink and downlink configuration proportion situation.
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