Wireless Sensor Networks (W) consist of a number of nodes such as distributed wireless sensors with limited battery power. The sensor network jointly monitors environmental conditions and physical parameters, such as temperature, sound , vibration , pressure , and movement in different locations. Nodes are connected with each other using wireless channels. One major challenge in sensor networks is energy consumption and reliability of the network with respect to the characteristics of wireless channel. Transmitted messages may not successfully received at the destination due to a variety of reasons, including collision of packets and poor channel conditions. Different methods are used to increase the reliability, the common method to improve the reliability in sensor networks is using error control schemes. The purpose of this thesis i to develop a plan to improve the error control and energy consumption for wireless sensor networks. In this work, a method based on alternative routes is proposed to improve the error control in wireless sensor networks. In this method, if a link failure is reported, the best alternative route will be found to be replaced with that link. To do this, an algorithm is proposed to find intermediate nodes,and also alternativelyome methods are introduced to compute error control using those intermediate nodes. Simulation results show that the performance ofthe channel coding scheme using alternative routes (ARQ-R, HARQ-R) is better than that of previous designs (ARQ, HARQ) according to the number of retransmissions. Additionally, performance of the HARQ-R design is better than any other design. By increasing SNR, energy consumption is reduced. It is shown that by increasing packet length, the number of retransmissions for successful reception of a packet is increased. As a result, to transmit the packets with large length in an efficient way, they could be broken into smaller packets before transmission. In order to minimize theumber of retransmissions and the energy consumption, a specific code rate for HARQ-R is proposed in each SNR. This code rate is significantly smaller than previous code rates. Keywords: 1.Wireless sensor networks 2.HARQ 3. Number of retransmissio 4.Energy consumption,