IST-4-027756 WINNER II D6.13.12 v1.0 Final CG “local area ...

WINNER II D6.13.12 v1.0normalised to the duration a super-frame TSF, and is evaluated for 5,000 sets of initial conditions, i.e. allparticipants initially commence with a uniformly distributed random clock value, as the coupling value atuser terminals αUTvaries. Base stations parameters are set to: αBS= 1. 1 , βBS= 0. 01 for the coupling,and Trefr,DL= 10⋅Tswhere T sis the duration of an OFDM symbol. User terminal parameters are set toβUT= 0.01 and Trefr,UL= 10⋅Ts. Figure 6.11 and Figure 6.12 show the cumulative distribution functionof the normalised time to synchrony for 10 and 25 participating user terminals.10.8cdf of T sync0.60.4α UT=1.1α UT=1.150.2α UT=1.25α UT=1.300 5 10 15 20 25T / T sync SFFigure 6.11: Local Area Results for 10 UTs10.8cdf of T sync0.60.4α UT=1.1α UT=1.150.2α UT=1.25α UT=1.300 5 10 15 20 25T / T sync SFFigure 6.12: Local Area Results for 25 UTsFrom these figures, the performance of the proposed slot synchronisation algorithm augments as thenumber of nodes in the system increases.For 10 user terminals, low coupling values is preferable, as synchronisation is always reached for α = 1. 1and α = 1. 15 . For higher coupling values, synchronisation is not always reached, but convergence isquicker.As the number of user terminals increases, the results for high coupling improve: synchronisation isalways reached for α = 1. 25 and α = 1. 3 and the time to synchrony is always below 10 super-frames. For90% of initial conditions, Tsyncis equal to 5 periods when α = 1. 3 .Page 43 (86)