# A Chaotic Compressive Sensing Based Data Transmission Method for Sensors within BBNs
## 1 Introduction  
With the thriving of technologies that relate to telecommunications, sensors and networks, the traditional internet with servers, personal computers, and cell phones acting as interconnection entities have been gradually transforming into the Internet of things (IoT), which connects vehicles, electric appliances, even human bodies and aims to realize the interconnection of everything. In order to achieve telemedicine, wireless body area networks (WBANs), for example, which represent the internet of human beings, implant specific sensors on the surface of or even in the body of individuals [1, 2, 3, 4]. Recently, apart from medical service and health care, WBANs also have the possibility of applications in military and aerospace fields, such as being applied to monitor vital signs of soldiers or astronauts and to implement first aid treatments. During routine training, WBANs could guard trainees by means of collecting training data and adjusting the training intensity. In military actions, WBANs could assist in developing attackers and defenders' strategies through monitoring body postures of both our armies and the opponents. On battlefields, WBANs could contribute to communications between soldiers as well as to data deliveries to commanders in the base. In addition, WBANs could provide help in monitoring physical status and positions of soldiers by embedding monitor sensors into military uniforms. Generally speaking, WBANs play an essential role in enhancing the accuracy, survivability, and connectivity in virtually every aspect of military operations. In addition, WBANs could be deployed along with astronauts, and by equipping spacecapsules with WBAN sensors, important data that concern space research as well as physical status information are transmitted from space to control centers through satellite channels. Such space applications broaden the scope where WBANs may exert themselves. The WBAN sensors embedded in human bodies can gather a wide range of vital signs, such as heart rates, blood pressures, electroencephalograms (EEGs), electrocardiograms (ECGs), and so forth [5], and some compressive sensing based methods have already been proposed to deal with such signals [6; 7]. The WBAN sensors send data they collect to monitoring centers, and thus distant diagnosis could be carried out and proper solutions may be proposed based on the data received. Because the transmission distances of WBAN sensors are limited, commonly, WBANs need the aid of additional typical network infrastructures to transmit data. For example, sensor nodes within WBANs that are distributed in various parts of individual bodies first send the data they collect to mobile phones, computers, satellites, or other types of terminals, and then these terminals transmit these data to monitoring centers or remote databases through Internet or satellite channels. WBANs are also sought after as they have expanded the service scope of traditional medical services that need specific time and workplaces and helped to realize a real-time and mobile mode of medical services. Apart from limited transmission distances, the WBANs that concern military or space technologies and medical applications often have a limited number of participant entities. When accompanied with the extension of application scopes, being applied in occasions such as major sport events, military actions, or disaster rescues, for instance, WBANs are required to be transferred from centralized data communication modes to distributed ones, and therefore body to body networks (BBNs) are gradually formed. BBNs can be regarded as extended WBANs, that is, multiple WBANs are interconnected with each other to generate a BBN. As a result, entities within WBANs could not only interact with other nodes in the same WBAN, but could also communicate across different WBANs, namely, WBANs can communicate with each other.