Claims:We claim,

A low cost, energy efficient, network of transport layer devices, having two separate classes of network accessibility, termed as Master and Slave stations, for fast establishment of radio data connectivity in dead-zones, using the said dual transport layer technology stack, allowing internet access to end-user devices and messaging services to said intra-network Stations without the need for an Access Point.
A device as claimed in claim 1, containing a long range radio module termed as the transporter radio working in the ISM band, for data transfer over large distances with interfacing support at the transport layer.
A device as claimed in claim 1, containing a processor with said multithreading support to which a WiFi module termed as the endpoint connector and the said transporter radio is connected.
A device as claimed in claim 1, which may include a said ethernet module for said internet connectivity in which case it will act as the said master device for the said entire network tree.
A method as claimed in claim 1, for maintaining optimum power usage using the said supervisory circuit using the said doze mode and said iterative power limitation method.
A method as claimed in claim 1, to send and receive said messages between said stations without need for external internet connection.
A method as claimed in claim 1, allowing multiple said Masters stations to exist in the said network tree in the said passive mode.
A method as claimed in claim 1, which allows a new said ethernet capable station to be elected as the said network tree’s Master if the original Master station goes down. , Description:The present invention relates to low energy devices that can be used to rapidly establish wireless connectivity in network deprived zones at minimal costs. The system described herein works in the Industrial, Scientific, and Medical (ISM) band.
In some embodiments, the system consists of a network of devices, herein referred to as “Stations”, containing low powered radio frequency (RF) transceivers, herein referred to as transporter radios, working in 2.4 GHz, 5 GHz ISM range. In some embodiments, radio modules of the nRF24L01+ family may be used to establish a mesh network, while in some other embodiments, XBee modules may establish mesh networking among themselves using the Zigbee protocol.
In one embodiment, the transporter radio is attached with high gain directional antennas for line-of-sight communication. In other embodiments, the transporter radio is attached with high gain omnidirectional antennas for non-line of sight, omnidirectional communication. The antennas have a range of over 100 meters. In some embodiments, they have a range of more than 1 km (radially measured for omnidirectional antennas).
In some embodiments, the transporter radio is connected to a microcontroller using a serial Receiver Transmitter (Rx/Tx) port. In other embodiments, the transporter radio is connected to the microcontroller using a Serial Peripheral Interface (SPI) bus. In some embodiments, a microprocessor is used in place of the microcontroller with necessary hardware support.
In some embodiments, the microcontroller or microprocessor hereafter referred to as the processor receives data packets from other Stations inside its own network (intra) or from other networks (inter) and transmits using the radio module connected to it as described above.
In some embodiments, the processor also consists of an endpoint connector, wireless radio module working on Wi-Fi or Bluetooth technology for end-user connectivity. User devices compliant with the above-mentioned technologies can connect to the Station for message transmission using techniques described below.
In some embodiments, the endpoint connectors run a DHCP server which automatically assigns a unique IP address (IPv4 or IPv6) to every connecting device. In other embodiments, a unique static IP is assigned manually to every connecting device.
In some embodiments, a software application is provided to the end user for data transmission purposes. The software application consists of an interface that allows users to browse the internet and download web pages. It also consists of an interface to send and receive data packets from other Stations.

The network consists of 2 mutually independent sections as illustrated in Figure. The core section consists of a mesh network established using Stations connected to radio frequency (RF) transceivers. Each node in this network may be attached or detached in an ad-hoc manner. In some embodiments a mesh routing algorithm has been implemented on one of these nodes designated as a master node. This master node is responsible for assigning addresses to each of the Stations and also routing packets to and from different Station. In some embodiments each Station is connected to one or more stations wirelessly in a tree topology resulting in only one path existing between any pair of Stations. This path may or may not include the Master node. Hence each Station by itself also has to perform a certain amount of routing function.
In some embodiments a data link layer routing protocol has been implemented on each node.

In some embodiments, a TCP connection is setup between the endpoint connector and the end device to transmit data packets to and from its parent station. In other embodiments, a UDP connection is used to send data packets between the pair. In one embodiment, a SCTP connection is setup for data transmission. The data transferred from all the connected end-devices and received by the Station is then input to a Time Division Multiplexer attached to the transporter radios, which then transmits the data to other stations using a protocol described later.
In some embodiments, the stations are powered using a DC power source like a battery (Lithium ion). In other embodiments, an AC-power adapter is used to power the module. In some other embodiments, solar panels are connected to the station to power it using solar energy.
In some embodiments, the Stations consists of a supervisory circuitry which uses a power management system to conserve energy. During network setup, the power management system puts the radio modules at full power, then iteratively decreases the power allocation to the radios until the least power level required to maintain a stable connection is achieved. The endpoint connectors and the transporter radios operate are also operated in a doze mode. In this mode, all network activity is kept at a bare minimum with only the required modules being awakened only during data transfers. All long range data transmission is done using the low energy transporter radio. In some embodiments, the above mentioned power management system is implemented as a hardware unit while in other embodiments, it is implemented as a software module running on the processor. This makes the whole system energy efficient, with observed battery lives being between a few months to years.
The protocol assumes the presence of a fully functional TCP/UDP stack running on each Station. The procedure of operation involves a proxy server running on each Station at a certain port. The credentials of this proxy server must be configured into each end device which attempts to use the network, else it will not be able to communicate with any node in the network. Through the end device interface, the proxy server accepts incoming TCP/UDP requests, and transmits them using the services provided by the aforementioned TCP/UDP stack running over the RF interface. The process of sending the TCP/UDP request and retrieving the requested resources is delegated to the TCP/UDP stack running over the RF interface. Once the response arrives, the proxy server returns the response to the corresponding end device through the end device interface.
The aforementioned TCP/UDP stack running over the RF interface assumes the Master of the RF network to be the gateway Station. In some embodiments this implies that the Master must have an Ethernet interface, capable of connection to the external network like the Internet. The Master must also be capable of running a Network Address Translation system, since all internal Stations will be allocated private IP addresses.
The Master selection algorithm in Figure 3 highlights the important facets of the protocol. Since this is an ad-hoc network, each Station is capable of assuming the role of the network Master. Once a Station is powered on, it will attempt to establish a connection, either directly or indirectly through hops to an already running Master Station, if any. The process of sending the request to join the network is delegated to a lower level stack. In some embodiments, the Zigbee stack may be delegated this process of connecting to the coordinator. In another embodiment, a stack based on the ANT protocol may be used to perform this function. In another embodiment a bluetooth piconet may be established over which a TCP/UDP stack may be running.
If the Station is able to successfully connect to a Master then it attempts to check whether the Master is Internet capable or not, by requesting a resource from the Internet. If this is successful then it completes the Master selection process. Else the Station checks whether it has any Internet capable network interfaces of its own. If it does not then it accepts the existing Master and completes the selection. Otherwise it will assume the role of the network Master itself. This will also be the case if it is unable to connect to a Master in the first place, even after waiting for a random back-off interval.
When the Station assumes the role of a network Master, it must run additional routing functions apart from the proxy server. This requires additional processing capabilities which a microcontroller is unable to fulfil. Hence there is a check in the header to determine whether the device is able to run a Master algorithm, otherwise it will not even run the Master selection algorithm and simply attempt to connect to any existing Master else wait for one to be activated.
Also once a Station assumes the role of a Master from a previously running Master, it must inform all other Stations of this change. This is simply achieved by sending a Master termination command to the previous Master (for which the Master must be listening). Upon receipt of this command, the Master will stop running the routing functions. After a certain interval all other nodes will come enter the disconnected state and run the Master selection algorithm. Hence they will connect to the new Master and complete the process.