WO2013005077A1

WO2013005077A1 - Wi-fi wt (walkie-talkie) simplex radio

Info

Publication number: WO2013005077A1
Application number: PCT/IB2011/052981
Authority: WO
Inventors: Hamdi Erhan Kum; Ihsan ERDIN; Ramachandra ACHAR; Erik Russell KRAMER; Ersin YIGITER
Original assignee: Hamdi Erhan Kum; Erdin Ihsan; Achar Ramachandra; Kramer Erik Russell; Yigiter Ersin
Priority date: 2011-07-05
Filing date: 2011-07-05
Publication date: 2013-01-10

Abstract

The new invention "Wi-Fi WT (Walkie-Talkie) Simplex Radio" presents a new kind of radio that can be used by every group or organizations to make simplex based point to point or point to multi -point wireless communication. In the new invention, important merits of the simplex communication and the features of Wi-Fi are combined to design an optimum simplex mode communication network that outperforms most conventional protocol based wireless communication networks. The invention provides for global communication coverage among multiple users, features to communicate via public networks based on Wi-Fi or land based WAN, LAN, Ethernet and dedicated server as well as dedicated network deployment for individual organizations. In the new communication system, Wi-Fi is not only used for connecting associated base stations but also to act as base stations. The proposed simplex system is designed to cover the entire globe under one network with an existing Infrastructures and Internet to make it cheaper, more affordable and easily deployable.

Description

WI-FI WT (WALKIE-TALKIE) SIMPLEX RADIO

Field of the Invention The present invention relates to a general radio communication focused on Wi-Fi enabled handheld devices such as walkie-talkies and/or cell phones that can be used by every organization or group of individuals to make simplex type point to point or point to multi-point wireless communication. Background of the Invention and Related Art

Wireless communication has become one of the main modes of communications for the mankind during the last two decades. Recent advances in wireless communication include MIMO (multiple input multiple output) communication, space-time coding, opportunistic communication, OFDM (orthogonal frequency-division multiplexing), CDMA (code division multiple access), GSM (global system for mobile), Flash OFDM and ArrayComm SDMA (space-division multiple access) systems.

Recently, Wi-Fi (wireless fidelity) based short range wireless access has gained immense popularity. Wi-Fi utilizes one of the IEEE 802.11 wireless standards to achieve a wireless network. Wi-Fi enabled devices such as laptops or PDAs can connect to a network and/or the Internet through wireless access point. Wi-Fi is the wireless technology to handle the networking/communication. Wi-Fi allocates internet connection globally and is transmitted by the radio waves. Radio waves are transmitted from antenna and Wi-Fi receivers pick them up. When a user receives the Wi-Fi signals, a wireless internet connection is produced and a user may be prompted to provide the user name and password if required to establish a wireless connection. State-of-the-art Wi-Fi connections are fast enough to allow the broadband type internet connection. Wi-Fi adds great levels of convenience for communication. Today it is very easy and inexpensive to build Wi-Fi networks. There are lots of commercial-off-the-shelf (COTS) devices for setting up Wi-Fi networks. There are lots of public hot spots everywhere and their number is growing every day. It is possible to benefit from the entire existing infrastructure or build a new one for a specific purpose and cover places for Wi-Fi access as needed with a fraction of a cost of conventional wireless radio systems.

Recently Voice over IP (VoIP) applications has also gained popularity. VoIP is a telephony system which uses TCP/IP networks to make the connections. In VoIP, mostly the communications are between only two people; that is point to point. VoIP needs a number to call. After a call connection, VoIP uses a duplex channel during the entire call. Minimum of 30 Kbits/sec in both ways are needed during the conversation. VoIP is very sensitive to delays, jitter and interruptions and its servers are complex. It is not possible to put a replay feature for previous conversations. Besides that the security of the communication can be a major challenge in VoIP applications.

Another quite popular and easy to adopt mode of communication is the "simplex" mode ((Push to talk - Release to listen) of communication. The term simplex refers to the mode of communication where radios communicate directly with each other, without any third-party assistance such as a repeater or a cell phone tower. If the radios are operated on battery power this type of communication is completely independent of any infrastructure, which makes it the only truly reliable way of relaying information in a timely fashion in case of serious emergency when power and telephones are not available.

Unfortunately, whether two or more people can communicate in simplex mode is highly dependent on the capabilities and locations of the radios involved. The quality of the antenna and the available power output determine the capability. However, even a powerful radio cannot always overcome some of the obstacles, such as an intervening mountain. The most common type of radio uses the 2-meter frequency band, which depends on relative line-of-sight communication. If a person is transmitting from a deep canyon it is very unlikely that anyone outside the canyon will receive the signal. Because of the constraints of relatively low-power and line-of- sight communication, simplex operation is usually challenged by covering the large area coverage and typically limited to small areas and few people. On the other hand, simplex communication is a very simple way of sending information to a point or to a group of points. It requires a very small bandwidth (BW) due to its burst characteristics. The bit rate of information being low and being burst in nature brings a lot of opportunities. Also, it is to be noted that the frequency spectrum is a very valuable resource and has to be used very carefully. In order to use it efficiently many methods have been devised. With the recent advancements in the design of micro controllers and digital signal processing technologies, it is possible to make the radios very smart. Today radios can be made very sophisticated and any protocol can be programmed into them. Since from the early days of the radios, many techniques have been used to increase channel efficiency. Protocol based systems were invented to solve the problem of channel and BW inefficiency. Sharing a channel or frequency between different groups was the first step to increase the system efficiency. Then depending on a protocol, sharing of a group of frequencies had been used. In this case depending on a demand from a group, the radios can be assigned a channel for the duration of the conversation. Also features like "channel scan" provides significant benefits for wireless radio communications, which allows a particular channel (or group of channels) to be declared of "higher priority" for communication. In protocol based systems there are several set of frequencies that can be used by a group of users. Instead of giving each group a frequency and leaving the channel idle when it is not used by the group, it is possible to use fewer number of frequencies and assign a frequency on demand. This method significantly reduces the idle channel times and increases the system efficiency by reducing the required BW while increasing the number of users (capacity) benefiting from the system. Protocol based systems have many standards and are still developing.

On the other hand network based systems use a different type of approach. Instead of building a system dedicated only to one network system, network based systems use already existing infrastructures to achieve the same goals as the protocol based systems without sacrificing any of their features. The immediate consequence of this approach is of course the significantly reduced cost. Network based systems require no base station hardware and software. Only a server will be needed instead.

The second major benefit comes from coverage point of view. While the network based systems can be deployed quickly and with a worldwide coverage, it is impossible to cover the entire world with one protocol based system because of the prohibitive cost of deployment and installation.

It is also to be noted that in network based systems, there are no set of frequencies. Instead they benefit from the protocol that multiplexes each and every user that uses the network. This approach significantly maximizes the spectrum efficiency as well as the user capacity.

In the new invention, important merits of the simplex communication, beneficial features of Wi-Fi as well as advantages of a network based communication are combined to design an optimum simplex mode communication network that outperforms most conventional protocol based wireless communication networks. The invented system henceforth is referred to as "Wi-Fi Walkie-Talkie Radio" or "Wi-Fi WT".

It is to be noted that, unlike the VoIP based communication systems, the proposed Wi-Fi WT is a simplex radio system and the communications can be point to multipoint (PMT) as well as point to point (PP). Radio here is always on (always listens to the channel). Communication is of burst mode and uses the channel only when needed. No dedicated BW is required all the time. Because of the simplex mode of operation, the Wi-Fi WT system does not suffer from sensitivities to delay, jitter or interference.

It is also to be noted that the proposed Wi-Fi WT system is different from the simplex mode of communication employed by GSM networks. GSM PTT is operator dependent, where the overage is determined by the operator. Handheld devices used in GSM networks should be GSM compatible and can't be used outside the coverage of the operator or by other networks. GSM does not provide for enhanced security, ACK mode of operation or reply modes. Besides that, GSM neither provides individual organization specific dedicated server operations. It also doesn't support channel scan based operations.

Summary of the Invention

In the new invention, important merits of the simplex communication, beneficial features of Wi-Fi as well as advantages of a network based communication are combined to design an optimum simplex mode communication network that outperforms most conventional protocol based wireless communication networks. In the new system, it is proposed to build a simplex and multi point system by defining the equipments to be used by any group or companies on a world wide scale. In the new communication system, Wi-Fi is not only used for connecting associated base stations but also to act as base stations. The proposed simplex system is designed to cover the entire globe under one network with an existing Infrastructures and Internet to make it cheaper, more affordable and easily deployable. For this purpose, most versatile properties of the simplex communication, network based servers and TCP/IP systems are combined to make a brand new World Wide Networking system. In the new system, handheld units and Intercom are designed to be network capable devices and are considered as elements of the network. Also the new invention allows for dual mode of operation as well as using Wi-Fi as a RF section. · In one embodiment, the new invention, proposed Wi-Fi WT system consists of several modules as described in Fig. 1. The system consists of: a) wireless module (or wireless modules) such as handheld radios, walkie-talkies or any Wi-Fi enabled devices, and wired devices (such as land based intercoms), b) a server (or servers) which is used to relay or repeat the conversations from the source radio to the destination radios depending on the pre-determined group lists, and c) Wi-Fi network and land based networks.

• Operation mode is simplex communication which provides a very simple way of sending information to a point or to a group of points. It requires a very small BW due to its burst characteristics. Consequently, related communication can be accomplished using low bit rates.

In one embodiment, the proposed Wi-Fi WT system significantly benefits from the advantages of deploying it with a land based network infrastructure. Instead of building a system dedicated only to one network system, proposed Wi-Fi WT can take advantage of the already existing network based infrastructures to achieve the same goals as the protocol based systems without sacrificing any of their features. This not only makes the deployment of the network based systems extremely fast, cost-effective and easy but also provides worldwide coverage.

When the radio is turned on, it will search and determine the Wi-Fi network around. After getting an IP address from the DHCP server, it will try to register to the Wi-Fi network server (WNS). When it is registered, user can now select which network group to talk or to listen. There may be several groups or users who may want to communicate with the turned on radio. In one embodiment, the implementation of the proposed Wi-Fi WT not only provides the use with handheld devices but also can be used in conjunction with land-based (desktop version of the hand-held) devices, such as intercoms.

When a group (note that an individual can be thought of as a group having only one member) is selected, the radio starts to receive all the details from the server. When someone places a call to that group, the radio will start to receive it. When the user wants to talk to that group, he simply presses the PTT button on the radio and talks. Each conversation has sender information, destination information and a time stamp.

The relaying from the server can be done in two modes, namely, a) ACK (acknowledgment) mode, where the server waits for an acknowledgment from each member of the group to confirm that the relayed conversation is received perfectly. Otherwise it repeats the conversation again, until all the group members acknowledge, b) Non ACKmode, where the server only relays the communication once.

• Depending on the memory of the radio, some portion of the conversation can be kept within the radio. The user can go back as much as she needs and replay the conversation. This feature is particularly useful to avoid any misunderstandings and makes the communication system very reliable and dependable. Depending on the customer needs every conversation can also be kept in the server, ordered, and sorted.

• In one embodiment, the proposed Wi-Fi WT provides for enhanced security features, security protocols (even military grade) for the communication. Due to the burst nature of the system (because of simplex communication), it is almost impossible to intercept the communications. The conversations can be encrypted at the device itself. Hence regardless of whether the transmission medium is Internet, a public hot-spot or a proprietary network, all transmitted data can be encrypted at the source and decrypted at the destination. Since the delay in simplex communication is not an issue and the amount of information is low due to low bit rate, very sophisticated encryption algorithms can be used. All the radios can be designed to ask a pin code after power up to prevent unauthorized access to the network.

Brief Description of the Drawings

The new invention can be easily understood by the following detailed drawings and detailed descriptions. The provided drawings illustrate only the preferred embodiments of the invention and therefore should not be considered as limiting in scope. Persons of ordinary skills in the art with the benefit of this description appreciate that the disclosed inventive concepts lend themselves to other equally effective embodiments. Fig. 1 shows the block diagram illustrating the components and modules for a general implementation of the proposed Wi-Fi WT System.

Fig. 2 shows the block diagram illustrating the components and modules of the proposed Wi-Fi WT system for the case with closed proprietary network implementation.

Fig. 3 shows the block diagram illustrating the components and modules of the proposed Wi-Fi WT system when implemented with both handheld wireless devices as well as land based intercom devices.

Detailed Description of the Embodiments

The new invention Wi-Fi WT presents a new kind of radio that can be used by every group or organizations to make simplex point to point or point to multi-point wireless communication. In the new invention, important merits of the simplex communication and the features of Wi-Fi are combined to design an optimum simplex mode communication network that outperforms most conventional protocol based wireless communication networks.

In the following, a detailed description of the preferred embodiments of the invention is given. Persons of ordinary skills in the art with the benefit of this description appreciate that the disclosed inventive concepts lend themselves to other equally effective embodiments and may be practiced without some of the specific details or with minor modifications to the described ones here. Also, indicated naming conventions for the devices in the figures are purely for the purpose of illustration, which can be done in any way based on an implementer's choice while using the inventive concepts outlined in this application. The Wi-Fi WT System

The details of the preferred embodiment of the new invention for the Wi-Fi WT System are outlined below. The new invention, "Wi-Fi WT System" consists of several modules as described in Figure 1. The system consists of: a) wireless module 1001 (or wireless modules) such as handheld radios, walkie- talkies or any Wi-Fi enabled devices, and wired devices (such as land based intercoms 1006), connected by either through Ethernet 1006 via a Router 1002 or by Access-Points (AP) 1007, b) a server 1003 (or servers) which is used to relay or repeat the conversations from the source radio to the destination radios depending on the pre-determined group lists, and c) Wi-Fi network(s) 1005 and Internet network 1004. The system consists of a) wireless module 1001 (or wireless modules) such as handheld radios, walkie-talkies or any Wi-Fi enabled devices, and wired devices (such as land based intercoms 3010), b) a server 1003 (or servers) which is used to relay or repeat the conversations from the source radio to the destination radios depending on the pre-determined group lists, and c) Wi-Fi network 1005 and land based networks 1004.

Wireless Modules

The wireless module is represented by handheld devices 1001 such as radio, walkie- talkie or any Wi-Fi enabled device. In the case of a Walkie-Talkie, it resembles a conventional radio in appearance however, with marked differences in how it operates and how it is made. Important difference between a conventional radio and the new Wi-Fi WT is that, Wi-Fi WT is a radio in which the RF section of a conventional radio is replaced by Wi-Fi (802.1 la/b/g/n) hardware. The wireless section being a Wi-Fi adapter, it is possible to use this radio in conventional/public Wi-Fi Networks.

Networks for Wi-Fi WT

The proposed Wi-Fi can be implemented with the following two types of networks, depending on the need of the user. a) Closed proprietary network: In a closed network, Figure 2, Wireless coverage

2003 composed of several different geographical networks where wireless devices 2001 are connected by AP's 2005 and the coverage of the network will be determined by the number of the AP's an by their locations. The Intercom devices 2004 will be connected by Ethernet network. If needed a Wi-Fi bridge can be used to connect these devices to the network instead of wired network. An existing network can be shared or a brand new Wi-Fi network can be built. In this case, the corresponding network operations are controlled by that organization. Since the operation belongs only to this organization, a dedicated server can be placed in the network. The design an building the proprietary network for Wi-Fi WT system is essentially building an ordinary Wi-Fi network. No extra conditions or features are needed to use an ordinary Wi-fi network for our implementation of Wi-Fi WT system b) Public networks: It is also possible to use the devices in public networks. Any Wi-Fi network providing Wi-Fi access network 1005 can be used with the proposed Wi-Fi WT system. c) Land based Networks: In one embodiment, the proposed Wi-Fi WT system significantly benefits from the advantages of deploying it with a land based network infrastructure 1004. Instead of building a system dedicated only to one network system, proposed Wi-Fi WT can take advantage of the already existing network based infrastructures to achieve the same goals as the protocol based systems without sacrificing any of their features. The immediate consequence of this approach is of course the reduced cost. With this approach of implementation, no expensive base station hardware/software are required for while implementing the Wi-Fi WT system instead only server (or servers) will be needed. This not only makes the deployment of the network based systems extremely fast and easy but also provides worldwide coverage. This approach also benefits from the protocol that multiplexes each and every user who uses the network, thereby significantly maximizing the spectrum efficiency as well as the user capacity. The Server

The server 1003 is used to relay or repeat the conversations from the source radio to the destination radios depending on the pre-determined group lists. Prior to deployment, all the information related to the groups has to be determined and programmed into the server. The main operational data-base will be kept in the server. The only information that has to be programmed into the radio is the name of the groups of the network they belong to. In order to reduce cost, some servers can be shared between different organizations. But if needed every operation can have its own server and put as much security as desired on top of it. A server can be anywhere in the network. To further increase the reliability, several redundant servers can be used.

In Figure 3, a possible implementation of the devices is given as an illustrative example. In this figure one can see that intercom devices and the wireless devices are only different at the network connection level. One of them uses a Wi-Fi bridge 3001 and the other uses Ethernet hardware 3009 to connect to the network. Rest will utilize the same hardware and software. Hand-held device will utilize a CPU 3005 which will do all the tasks to convey verbal conversation to the Server through the Network. It will drive the display 3002, the keypad 3003 and the buttons 3004 for the user interface. Audio Circuits 3006 will sample the incoming communication to be sent to the network and will reassemble or convert the conversation coming from the network to audible sound. In order to make the communication secure either an Encryption module 3009 can be used or this function can be implemented by the CPU. Similarly to increase the efficiency of the system, an audio codec hardware 3007 can be utilized.

The provided drawings and above descriptions are only the preferred embodiments of the invention and therefore should not be considered as limiting in scope. Persons of ordinary skills in the art with the benefit of this description appreciate that the disclosed inventive concepts lend themselves to other equally effective implementation and embodiments.

Mode of Operation

Operation mode is simplex communication which provides a very simple way of sending information to a point or to a group of points. It requires a very small BW and low bit rate due to its burst characteristics. Functioning of the Wi-Fi WT System

When the radio is turned on, it will search and determine the Wi-Fi network around. After getting an IP address from the DHCP server, it will try to register to the Wi-Fi network server (WNS). When it is registered, user can now select which network group to talk or to listen. There may be several groups or users who may want to communicate with the turned on radio.

When a group (note that an individual can be thought of as a group having only one member) is selected, the radio starts to receive all the details from the server. When someone places a call to that group, the radio will start to receive it. When the user wants to talk to that group, he simply presses the PTT button on the radio and talks. Each conversation has sender information, destination information and a time stamp. The relaying from the server can be done in two modes, namely, a) ACK (acknowledgment) mode, where the server waits for an acknowledgment from each member of the group to confirm that the relayed conversation is received perfectly. Otherwise it repeats the conversation again, until all the group members acknowledge, b) Non ACKmode, where the server only relays the communication once.

Depending on the memory of the radio, some portion of the conversation can be kept within the radio. The user can go back as much as she needs and replay the conversation. This feature is particularly useful to avoid any misunderstandings and makes the communication system very reliable and dependable.

Depending on the customer needs every conversation can be kept in the server too. The conversations at the server can be decrypted or not. In any case all the conversations are kept in the data-base. In server, every conversation can be ordered depending on the time stamp. If some group member stays out of coverage for a while and comes back into coverage, certain portion of the old conversations are loaded from the server and the user can play back and listen to the conversations when the user is out of coverage. Another useful feature will be to convert all the conversations to text at the server. Then it may be easier to search for a certain conversation or it will be easier to monitor the contents of the conversations if needed. Instead of keeping voice recordings of the conversations, it may be more convenient for the organizations to keep the written text. Security of the communication in Wi-Fi WT System

In one embodiment, proposed Wi-Fi WT provides for enhanced security features, security protocols (even military grade) for the communication. a) Due to the burst nature of the system (because of simplex communication), it is almost impossible to intercept the communications. Since there is typically other traffic on the network, the proposed Wi-Fi WT based communication traffic is buried into the traffic generated by other sources. Since the Wi-Fi is a low power system, many AP's are typically deployed. Also in case of using public systems, it is impossible to determine where the particular radio is located. In addition, all the radios are free to change AP's as they are roaming. These all adds to the overall enhanced security for the communication. b) The conversations can be encrypted at the device itself. Hence regardless of whether the transmission medium is Internet, a public hot-spot or a proprietary network, all transmitted data can be encrypted at the source and decrypted at the destination. Anybody trying to listen to these conversations has to deal with the encryption of the system. Since the delay in simplex communication is not an issue and the amount of information is low due to low bit rate, very sophisticated encryption algorithms can be used. c) All the radios can be designed to ask a pin code after power up to prevent unauthorized access to the network. To further increase the security of the system, especially in military applications, voice recognition hardware can be implemented at the server. This feature will determine whether the voice belongs to the real user or not. If not, the message will not be repeated by the server to the group and the device that is sending the message will be disabled.

Use with land based devices

In one embodiment, the implementation of the proposed Wi-Fi WT not only provides for use with hand-held devices but also can be used in conjunction with land based (desktop version of the hand-held) devices, such as intercoms. Land based devices work exactly the same way as the hand-held devices except being in a fixed location. In this case, the intercom device consists of all the features of a hand-held device but it is connected to a network through an Ethernet connection instead of Wi-Fi. It can have the same display/keypad and user interface and same security features as that of the handheld device. Such an implementation is useful for purposes such as monitoring the communication among the entire group.

Claims

We claim the concept and product development based on simplex communication among handheld radios (wireless) as well as land based intercoms (wired), via Wi-Fi connection and land based network and servers, to provide global communication coverage among multiple users, with features to communicate via public networks based on Wi-Fi or land based WAN, LAN, Ethernet and dedicated server as well as dedicated network deployment for individual organizations. We claim the use of Wi-Fi not only for connecting associated base stations but also to act as base stations. We claim design of handheld units and Intercoms to be network capable and are considered as elements of the network.

The method of claims 1, further that:

a) The new Wi-Fi WT system can adopt all the existing network connections, devices and protocols to implement this system. For Wi- Fi connection, any available configuration under IEEE 802.11 standard can be used. In building the wired network, LAN, Internet, Ethernet, Wi-Fi and all the required protocol layers can be utilized to connect the simplex devices together hence to form the backbone of the network system. We will be benefiting from the above mentioned infrastructure to make our base station hardware simpler, cheaper, instead of building and manufacturing custom systems and implementing custom designed protocols. They can be designed to benefit from the properties of the communication layers (physical + datalink + network + transport ) for wide area coverage. The existing network can be of any size, ranging from a single router connecting two devices or the Internet connecting multiplicity of devices in a large area. The proposed system can also be used in a closed network using standard components, dedicated to performing a certain operation.

b) The implemented system can be of both types: with server or without server. If a server (or servers) is used in the proposed system, it can be of the type of dedicated server per user group or sharing of a server with multiple groups of users.

3) The method of claims 1 and 2, further that:

a) The handheld or land based devices in the proposed Wi-Fi WT system, can be single mode wireless devices (which are conventional wireless devices with RF sections replaced by a Wi-Fi bridge or Intercom devices that will connect through Ethernet) or multi-mode devices (which use similar hardware user interface like a single mode device plus one or more additional hardware for connecting (benefiting) to other networks where there is no Wi-Fi coverage or where another network connection is preferred for some reasons. Typical scenarios of multimode device operations are, but not limited to: dual mode Wi-Fi + LOE satellite devices benefiting Low orbit satellites as the alternative network, dual mode RF +Wi-Fi devices where classical RF circuits of a wireless device can be activated instead of Wi-Fi to connect to an alternative network, and smart phone applications that can be used to benefit from the simplex system defined in this patent, etc.

b) Communication proposed in the new system can be point-to- multipoint(PMP: with more than two users) or even point-to-point (PP: with only two users)

4) The method of claims 1 , 2 and 3, further that the: a) The communication proposed in the new system can be encryption based or non-encryption based. b) In case of encryption based implementation, any available kind of encryption key or technique can be adopted and it can be implemented system-wide, such as, but not limited to: device (source)-to-device (destination) and device-to-server, server-to-device. Also each group can have the option of having the same or different encryption key or encryption technique. A different or same encryption key or technique can be adopted for each transmission between source and destination servers as well as for each element of multipoint repetition. c) Also voice recognition and user authentication on the server can be adopted based on a previously stored pattern as well as asking a PIN code if the user seems suspicious on his device. d) For the devices (handheld or intercom type), security features such as the following, but not limited to can be adopted: PIN code at power-on against unauthorized access to services, Registration of each device to server at device boot-up and following a location and network change to designate the location at the network thus avoiding any blockage from firewalls and NAT.

method of claims 1 , 2, 3 and 4, further that the:

a) Communication can be uncompressed or compressed to reduce the bit rate. In case of compressed option, any available technique can be used for the purpose of data compression. Also channel scan based operation can be adopted.

b) Transmission of the data can be accommodated without or with error correction and/or detection coding to improve the quality and reliability of the communication. c) Messages can be stored at the server, the communication can be sorted depending on the time stamps of each message (or by user specified preferences).

d) A list of all previous communications can be kept at the server side to guarantee the safe and complete transmission of each and every message. Keeping history of all messages at server side (encrypted or otherwise), thus making it available to authorized users for monitoring from a secure, password protected web site.

e) Old messages can be resent to the devices which were outside the coverage or turned-off temporarily (using ACK mode to achieve this automatically).

f) Voice messages can be converted into text messages at the server side to keep a written log of conversations for further monitoring and search demands. This will facilitate the use of a search engine to find a specific communication.

g) Channel scan based features can be adopted in the proposed Wi-Fi WT radio. Simplest form of implementation is the priority channel scan mode in which case a particular channel is declared a "priority channel" and which always takes the priority when there is a communication in that channel. More general implementation can be made where several channels are assigned a level of priority. Since the replay mode is also implemented, even if another channel takes over, no conversations of any other channel will be lost and the conversations can be re-sent by the server whenever user returns back to a channel from a higher priority channel.

6) The method of claims 1 , 2, 3, 4 and 5, further to: a) Usage of HTTP port for some networks which only allow port 80 to connect to the Internet and block all others.

b) Define user groups (by the administrators of the group) at the server with web based software, to define user groups at the devices and uploading them to the server and also to define users with membership to several groups.

c) Use of small browser on the devices for password entering capability for some Wi-Fi networks which require a password entry from a browser.