# On Localized Countermeasure Against Reactive Jamming Attacks in Smart Grid Wireless Mesh Networks
## 2 Related Work  
The jamming attacks to wireless networks are evolving at a higher rate than their available preventive countermeasures. The main objective of a jamming attack is to effectively jam the communication within the networks without being discovered and located. In the literature, there are various countermeasures proposed against different jamming attack models. Based on different techniques and the technology involved, the solution can be broadly classified into: (1) Physical layer approaches, (2) MAC layer approaches and (3) Network layer approaches. The countermeasures against the jamming attack at the physical layer makes use of technologies such as FH spread spectrum [5; 6; 7] and Direct-Sequence Spread Spectrum (DSSS) [8; 9] which requires very excessive computational resources. In ref. [6], [PERSON] et al. introduced FH against jamming attacks by shifting the wireless communication frequency to secure one so as to dodge the jammed communications according to channel sequences generated by shared secret Transmission Security Key (TRANSEC). To solve the leftover problem of how to distribute the TRANSEC key in this method, [PERSON] et al. [7] proposed an Uncoordinated FH (UFH) scheme as a point-to-point anti-jamming manner. Due to the fundamentally low spectral efficiency from the design of proactive hopping procedure, a message driven frequency hopping technique has been recently introduced to achieve higher efficiency [5]. Using CDMA technology, [PERSON] et al. in ref. [8] proposed a countermeasure for the jamming attack, but as the approach is based on a dynamic tree reemerging scheme, there is a huge maintenance overhead and furthermore, computing the orthogonal codes is required with a considerable amount of latency. In ref. [9], using CDMA technology, [PERSON] et al. propose a solution for the jamming attack but it involves the issue of common key sharing problem. In ref. [11], [PERSON] et al. introduced the channel surfing against jamming attacks at MAC layer. This approach is inherently based on FH and switches channel in an on-demand manner. The important issues involved in this approach are scalability, latency and synchronization of coordinated communication channel shifting across the network. Furthermore, in ref. [10], [PERSON] et al. introduced a spatial retrieval method, where a mobile node is physically repositioned out of jammed region, but this may result in parts of the network getting isolated. In addition, [PERSON] et al. in ref. [15] introduced a link layer countermeasure technique to solve the critical challenges in exploring the un-jammed survived bits in wireless messages from the reactive jamming attacks in order to re-assemble them into the originally transmitted messages. This literature provides the system delivering wireless messages by harnessing the invocation time of the reactive jammer, but it could not avoid the activation of the jammer. In addition, a linear programming based countermeasure in ref. [16] has been introduced against a wireless jamming threat to disrupt network flow. However, such types of solutions are not practical as they cannot be implemented in real time in the Smart Grid wireless mesh networks. In ref. [12], [PERSON] et al. proposed a solution at the network layer level, where the jammed nodes cooperatively identify the jammed region and a path is identified to detour this jammed region. The problem with this approach is that it may result in a considerably large part of the isolated network. Besides the countermeasures described above, an area mapping based defense from the network layer has been investigated in JAM [12]. In this approach, the wireless devices under the jamming attack would map cooperatively the jammed area a path in order to detour communication messages around the identified area. A deficiency on the scheme would be the possibility of creating unnecessarily large jammed area to avoid the jamming attack, which might result in the isolated networks.