# Moving Ad Hoc Networks--A Comparative Study
## 2 Mobile Ad-Hoc Network (MANET)  
In MANET, nodes/devices can move independently and freely in all directions. MANET does not have any infrastructure (base station) where each node in the network acts as a router. The routers are free to move randomly and organize themselves. Therefore, the wireless network topology may change unpredictably and frequently. For example, Figure 2 represents a mobile ad hoc network where we have four devices that can communicate with each other. The first device can communicate with all other devices (Devices 2, 3, 4, and 5), but if another device wants to communicate with other devices (for example Devices 2 and 4 or Devices 3 and 5) they must route through Device 1.  
Characteristics of MANET:  
Dynamic network topologies: The nodes can move freely and independently in any direction. The network topology may change randomly at any time (Figure 3).  
Multi-hop: Each node acts as a host and as a router in which the nodes are linked through wireless channels in the network. The message goes through multiple nodes from the sender to the receiver due to the bounded transmission radius.  
Limited battery power: Wireless has a finite bandwidth and the nodes have limited battery power. Therefore, power conservation is a substantial design optimization condition.  
Temporary and rapidly deployable: The network does not have any infrastructure (base station). In nature, this network is temporary. The nodes are rapidly deployable; for instance, when the nodes are in the transmission ring, they make an ad hoc network.  
Infrastructure-less, distributed, and self-organizing: There is no centralized control; due to unreliable links, MANET relies upon the collaboration of the participating nodes.  
Scalability: Because of the limitation of power and memory on the nodes, scalability is an issue when we consider a large network size.  
Low Bandwidth: This wireless network has a shorter transmission range than the fixed infrastructure network. Therefore, its communication is lower than wired communication due to the impact of fading, interference, noise, and multiple accesses.  
Figure 2: Infrastructure-less Network.  
* Advantages and applications of MANET:
* It has more flexibility.
* It has better mobility.
* The network can be set up at any time.
* It is more economical.
* It can provide access to geographical position information and services. There are several applications for MANET:
* The local-level.
* The communication sector.
* The military battlefield.
* Personal area networks.
* Business associates.
* Information exchange when network infrastructure is destroyed, etc.
* MANET routing protocols classification.  
MANET is the primary use for a wireless ad hoc network. In MANET, other participating nodes randomly move in the created wireless ad hoc network. Because the communication link between the two devices changes from time to time, it is very difficult to create a MANET for devices to move dynamically in the network. However, to manage the content change of the route traffic, the main challenge of building a MANET is suspended.  
Most of the research focuses on routing and link connectivity. To evaluate the performance of this type of network, capacity and throughput are good metrics. MANET routing protocol classification is separated into three types, as shown in Figure 4. Table 1 shows a summary of the existing surveys in MANET.  
Figure 3: Characteristics of MANET.  
Due to decentralization and mobility, MANETs have a lot of issues and challenges.  
* Routing,
* Bandwidth-limited wireless range,
* Energy,
* Dynamic topology-induced changes in routes,
* Security threats,
* Mobility-induced packets may be lost,
* Limited battery life,
* Scalability problems,
* Routing overheating.