Advanced Power Control for UTRAN LTE UL
Author
Quintero Goncalves, Nestor
Term
10. term
Publication year
2008
Pages
95
Abstract
3GPP selected SC-FDMA for the LTE uplink. Because SC-FDMA keeps users in the same cell from interfering with each other (intra-cell orthogonality), the main limitation becomes interference from neighboring cells. This is intensified by a frequency reuse factor of 1, where all cells use the same spectrum, making transmit power control critical. The standard defines a power-control rule with two parts: open loop and closed loop. Open-loop power control (OLPC) compensates for slow effects such as path loss and shadowing, while closed-loop power control (CLPC), which is vendor-specific and still under study, reacts to fast changes and helps manage interference. In this thesis, OLPC is analyzed to set a reference baseline, and two CLPC techniques are proposed to improve upon it. All methods are evaluated in a static simulator that models slow variations. We compare them using key indicators such as cell outage and total cell throughput. The results show up to a 22% increase in outage user throughput (i.e., for the worst-served users), together with about a 5% improvement at the cell level. Parameters can also be tuned to obtain larger gains at the cell level at the cost of smaller gains for outage users.
3GPP har valgt SC-FDMA til LTE-uplink. Fordi SC-FDMA gør, at brugere i samme celle ikke forstyrrer hinanden (intra-celle-ortogonalitet), bliver den største udfordring interferens fra naboceller. Problemet forstærkes af frekvensgenbrugsfaktor 1, hvor alle celler bruger de samme frekvenser, og derfor er effektkontrol (power control) afgørende. Standarden beskriver en effektkontrolregel med to dele: åben sløjfe og lukket sløjfe. Åben sløjfe-effektkontrol (OLPC) kompenserer for langsomme variationer som stisdæmpning og skygning, mens lukket sløjfe-effektkontrol (CLPC) er leverandørafhængig og stadig under forskning; den kan reagere hurtigt og hjælpe med at styre interferens. I denne afhandling analyseres OLPC for at etablere en reference, og der foreslås to CLPC-teknikker for at forbedre den. Alle metoder testes i en statisk simulator, der modellerer langsomme variationer. Vi sammenligner dem ved hjælp af nøgletal som cellens outage og samlet cellegennemstrømning. Resultaterne viser op til 22% forbedring af outage-brugeres throughput (de dårligst stillede brugere) sammen med omkring 5% forbedring på celleniveau. Parametrene kan også indstilles, så man opnår større gevinst på celleniveau på bekostning af en mindre gevinst for outage-brugere.
[This apstract has been rewritten with the help of AI based on the project's original abstract]
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