2. Motivations
Since each node plays the dual role of data gathering
and data relaying, the energy consumption at each node
can be divided into the two corresponding parts. To simplify
the discussion, we assume that the proportional energy
allocation for data relaying in each node’s lifetime
can be achieved by the proportional power control
mechanism.
To investigate the importance of power control on data
relaying, let us look at an example sensor networks with
topology shown in Fig. 1. In this example, n1 and n2 are
sensor nodes and d1 is a sink node. The distances between
every two neighbor nodes are 100 m. There is a route from
n1 to d1 via n2. n2 always relaying the traffic from n1 to d1
until it runs out of its energy. Each sensor node has 1 Joule
initial energy. The node energy dissipation models and
parameters are set as same as those in [6].
In the first group of simulation, we set the relaying
power ratio at n2 as 0.5 and 0.6, respectively and obtain
data throughput at the sink node d1 as shown in Table 1.
We can find that different relaying power ratios deployed
at n2 result in different data throughput received at the
sink node d1. Thus, the relay power ratio does affect the
performance of end-to-end data throughput.
In the second group of simulation, we set the source
rate at n1 as 250 Kbps and 1 Mbps, respectively, then measure
the total energy consumption of node n1 and n2 in
transmitting 1Mbits traffic to d1. As shown in Table 2,
although the data throughput received at sink node d1
are equal, the total energy consumption is different with