To indicate the effect of power consumption, we calculate the real power consumption based on TABLE 2.2. In Figure 5.5, we observe that the time for the UE to enter RRC IDLE become longer at lower packet arrival rate;
it implies real power consumption is relatively low. In addition, power con-sumption is increased when CIDLE = 4.8s, which is different from the trend of power-saving factor, as shown in Figure 5.3. It is obviously to see that the real power consumption model can express more reality than power-saving
0.8
Figure 5.3: Power-saving factor with RRC states transition (CIDLEDRX = 1000 ms).
factor in this situation. And we can know if the user uses some applications like web or other some non-GBR(Guranteed Bit Rate) services, we suggest the CIDLE can set in 1 or 2 seconds which can be more power-saving when the UE can stays in RRC IDLE for longer time.
5.5 Transmission Delay with RRC States Transition in Different C
IDLEFigure 5.6 depicts the average transmission delay under different packet ar-rival rate λ. The average transmission delay decreases as the packet arar-rival
0 500 1000 1500 2000 2500
1500 2000 2500 3000 3500 4000 4500
Time Period(ms)
CIDLE Time(ms) TL
TIDLE
Figure 5.4: The trend of E[TL] and E[TIDLE] in different CIDLE.
rate increases since the UE stays in RRC IDLE state for shorter time. Fur-thermore, Figure 5.5 and Figure 5.6 show that there is a trade-off between the transmission delay and the real power consumption. And due to there is much higher delay when the UE enters RRC IDLE, the applications like VoIP or other some GBR services do not aptly to enters RRC IDLE.
5.6 Probability of the UE enters RRC IDLE
We use Figure 5.7 as an evidence to show that the probability of staying in RRC IDLE state for UE decreases as the the packet arrival rate increases.
It implies that there is a high probability of entering the RRC IDLE state when UE with lower packet arrival rate.
600 700 800 900 1000 1100 1200 1300
0.0005 0.001 0.0015 0.002 0.0025
Real Power Consumption (J)
Packet Arrival Rates (1/ms)
CIDLE=1.2s CIDLE=2.4s CIDLE=3.6s CIDLE=4.8s
Figure 5.5: Real Power Consumption in 1 second.
100 150 200 250 300 350 400 450 500
0.0005 0.001 0.0015 0.002 0.0025
Transmission Delay (ms)
Packet Arrival Rates (1/ms)
CIDLE=1.2s CIDLE=2.4s CIDLE=3.6s CIDLE=4.8s
Figure 5.6: Average packet transmission delay with RRC states transition when N = 2 and CIDLEDRX = 1000 ms.
0 0.1 0.2 0.3 0.4 0.5 0.6
0.0005 0.001 0.0015 0.002 0.0025
Probability
Packet Arrival Rates (1/ms)
CIDLE=1.2s CIDLE=2.4s CIDLE=3.6s CIDLE=4.8s
Figure 5.7: Probability of the UE enters RRC IDLE.
Chapter 6 Conclusions
In this thesis, in order to realize the impact of RRC states transition on DRX mechanism, we derive some numerical functions to model this effect from simple probability theory. By dividing the DRX and RRC operations into several independent parts, we can calculate them separately and then combine the result eventually. We obtain the power saving factor with RRC effect, real power consumption, and packet transmission delay. The analyt-ical results show that there is a trade-off between the power consumption and transmission delay, which has also been verified. Furthermore, under lower packet traffic arrival rate, the UE enters RRC IDLE states with higher probability, thus it can save much more power. This work can be extended to determine the best DRX and RRC operation parameters.
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Vita
Cheng-Wen Hsueh
He was born in Taiwan, R. O. C. in 1989. He received a B.S. in De-partment of Electronic Engineering from Chung Yuan Christian University in 2011. From July 2011 to August 2013, he worked his Master degree in the Mobile Communications and Cloud Computing Lab in the Department of Communication Engineering at National Chiao-Tung University. His re-search interests are in the field of wireless communications and mobile com-puting.