Department of Computer Science and Engineering, Kangwon National University, Chuncheon, Gangwondo, 200-701, Korea.
Sensors (Basel). 2010;10(4):2919-45. doi: 10.3390/s100402919. Epub 2010 Mar 29.
Congestion in a wireless sensor network causes an increase in the amount of data loss and delays in data transmission. In this paper, we propose a new congestion control technique (ACT, Adaptive Compression-based congestion control Technique) based on an adaptive compression scheme for packet reduction in case of congestion. The compression techniques used in the ACT are Discrete Wavelet Transform (DWT), Adaptive Differential Pulse Code Modulation (ADPCM), and Run-Length Coding (RLC). The ACT first transforms the data from the time domain to the frequency domain, reduces the range of data by using ADPCM, and then reduces the number of packets with the help of RLC before transferring the data to the source node. It introduces the DWT for priority-based congestion control because the DWT classifies the data into four groups with different frequencies. The ACT assigns priorities to these data groups in an inverse proportion to the respective frequencies of the data groups and defines the quantization step size of ADPCM in an inverse proportion to the priorities. RLC generates a smaller number of packets for a data group with a low priority. In the relaying node, the ACT reduces the amount of packets by increasing the quantization step size of ADPCM in case of congestion. Moreover, in order to facilitate the back pressure, the queue is controlled adaptively according to the congestion state. We experimentally demonstrate that the ACT increases the network efficiency and guarantees fairness to sensor nodes, as compared with the existing methods. Moreover, it exhibits a very high ratio of the available data in the sink.
在无线传感器网络中，拥塞会导致数据丢失量增加，并延迟数据传输。在本文中，我们提出了一种新的拥塞控制技术（ACT，基于自适应压缩的拥塞控制技术），该技术基于自适应压缩方案，在发生拥塞时通过减少数据包来实现拥塞控制。在 ACT 中使用的压缩技术包括离散小波变换（DWT）、自适应差分脉冲编码调制（ADPCM）和游程长度编码（RLC）。ACT 首先将数据从时域转换到频域，使用 ADPCM 缩小数据范围，然后在将数据传输到源节点之前，借助 RLC 减少数据包的数量。它引入了基于 DWT 的优先级拥塞控制，因为 DWT 将数据分为四个具有不同频率的组。ACT 按照数据组的频率成反比为这些数据组分配优先级，并按照优先级成反比定义 ADPCM 的量化步长。RLC 为优先级较低的数据组生成较少数量的数据包。在中继节点中，ACT 在发生拥塞时通过增加 ADPCM 的量化步长来减少数据包的数量。此外，为了便于反向压力，队列根据拥塞状态自适应地进行控制。实验表明，与现有方法相比，ACT 提高了网络效率，并保证了传感器节点的公平性。此外，它在接收器中具有非常高的可用数据比例。
