Submitted By :-

Narayan Prajapat

2011uec1273

EC-2

CONTENTS

INTRODUCTION

SYSTEM MODEL

OUTAGE PROBABILITY MINIMIZATION

BATTERY ENERGY CONSUMPTION

MINIMIZATION PROBLEMS

CONCLUSION

INTRODUCTION

Improving the energy efficiency of wireless communication systems. Energy harvesting (EH) technique has been regarded as an effective way to achieve this goal. The capability that EH transmitters can harvest the external energy makes communications environmentally friendly since such external energy sources, e.g., solar energy, wind energy, and vibration energy, are clean and renewable in general

SYSTEM MODEL

Consider a point-to-point communication link with hybrid energy supply as depicted in Fig, where the transmitter is powered by a primary battery and an energy harvester. The primary battery is the traditional rechargeable battery, which has its initial energy capacity. The energy storage is used to store the energy from the energy harvester, which cannot be charged and discharged at the same time

Note:- the system model in this work is different to that

First, we consider only one energy storage in the transmitter, instead of two energy storage systems which reduces the implementation cost.

Second, a primary battery is implemented to power the transmitter since the harvested energy is usually unstable and may be insufficient toguarantee the QoS of data transmission

THREE STAGE IN SYSTEM MODEL EH stage: During [0, ρT], S1 is switched on and S2 is switched off, the energy storage accumulates the harvested energy. Since the storage cannot be charged and discharged simultaneously

Switching stage: At time t = ρT, an amount of Eg Joule from the primary battery is scheduled for the transmitter to accomplish the data transmission in case of insufficient energy from the energy harvester

Data transmission stage: During (ρT, T], S1 is switched off, S2 is switched on, and data is transmitted. During this stage, the transmitter is powered by both the energy storage and the primary battery

OUTAGE PROBABILITY MINIMIZATION

we will derive the optimal saving factorto minimize the outage probability for the considered hybrid energy supply system with a given battery energy. For a given throughput requirement R0, the outage probability could be written as

BATTERY ENERGY CONSUMPTIONMINIMIZATION PROBLEMS

For sufficiently large harvesting power, the transmitter may deliver all data packets by the harvested energy solely. But in general, successful transmission cannot be achieved without utilizing the energy from the primary battery. Hence, the optimal transmission scheduling policy to minimize the battery energy consumption by proper packet scheduling and saving factor optimization is very important

We now focus on the energy efficient transmission scheduling problem in hybrid energy supply system with the save-then transmit protocol. An N-slot transmission model is shown in Fig. 2 where B = {B0, B1, . . . , BN−1}, λ = {λ1, λ2, . . . , λN},and γ = {γ1, γ2, . . . , γN} are the traffic profile , the harvesting power, and the channel gain in each slot, respectively.In each slot, the system operates under the save then-transmit protocol.

CONCLUSIONwe investigate the hybrid energy supply communication system under the save-then-transmit protocol. First, the optimal saving factor for the outage probability minimization problem is derived. We find that, for sufficiently large spectral efficiency requirement, harvested energy is unnecessary and it is preferred to transmit with battery energy only Then, we formulate the BECM problems In the case that full knowledge about the packet arrival, the harvesting power, and the channel gain are available,

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