ROAMING ENCODED INFORMATION READING TERMINAL
The present application claims the benefit of U.S. patent application Ser. No. 14/107,048 for a Roaming Encoded Information Reading Terminal, filed Dec. 16, 2013 (and published Apr. 10, 2014 as U.S. Patent Application Publication No. 2014/0098792), now U.S. Pat. No. 9,167,421, which claims the benefit of U.S. patent application Ser. No. 13/470,510 for a Roaming Encoded Information Reading Terminal, filed May 14, 2012 (and published Nov. 15, 2012 as U.S. Patent Application Publication No. 2012/0287910), now U.S. Pat. No. 8,611,309, which is a division of U.S. patent application Ser. No. 12/070,895 for a Roaming Encoded Information Reading Terminal, filed Feb. 21, 2008 (and published Aug. 27, 2009 as U.S. Patent Publication No. 2009/0213811), now U.S. Pat. No. 8,179,859. Each of the foregoing patent applications, patent publications, and patents is hereby incorporated by reference in its entirety. The invention is generally related to data collection systems employing encoded information reading (EIR) terminals and is specifically related to a system and method of data communication in a data collection system employing EIR terminals. Encoded information reading (EIR) terminals equipped with wireless communication interfaces are widely used in retail stores, shipping facilities, etc. The protocol most widely used for providing data communications within the data collection system employing EIR terminals is Internet Protocol (IP) version 4. The routing scheme of IPv4 determines the destination network information from the destination IP address of a datagram. This can be analogized to the “old” phone numbering scheme (which became out-of-dated with the introduction of phone number portability), where an area code and a three-digit prefix determined the geographical location of the land-line phone. Whenever a land-line phone subscriber moved from a geographical zone served by one local exchange to a geographical zone served by another local exchange, the subscriber's phone number would change to satisfy the area code and local exchange-based numbering scheme. An IPv4 address consists of network address bits and host address bits, as defined by a netmask. Continuing the analogy, the network address bits can be considered playing the role of the area code and local exchange part of the phone number. Hence, whenever a networked device moves out of the zone served by the network defined by the network address bits of the device's IP address, the device must change its IP address, since IPv4 routing would not work and IP datagrams to the device would not be delivered if the device is connected to a network whose network address is different from the network part of the device's IP address. The requirement of changing the IP address by a roaming device is not of a great concern unless the device, e.g., an EIR terminal equipped with a wireless network interface, moves from one network to another while at least one communication session (e.g., a TCP connection) in which the terminal participates, is active: the TCP connection would be lost immediately upon the terminal changing its IP address. Accordingly, there is a need for a method of keeping the active communication session alive while a wireless networked device, e.g., an EIR terminal, is roaming from one network to another. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. There is provided a portable encoded information reading (EIR) terminal for incorporation in a data collection system. The data collection system, schematically shown in In one aspect, the networks 110 In another aspect, an EIR terminal can establish one or more wireless links with one or more peer EIR terminals, with a wireless AP, or with a wireless portal. The EIR terminal can provide IEEE 802.11-conformant wireless distribution system services, including association, disassociation, distribution, integration, and re-association, to the peer EIR terminals, thus acting as a wireless mesh access point (MAP) or a wireless mesh point portal (MPP). In another aspect, a wireless AP or portal can be provided, e.g., by an infrastructure AP or portal, or by a mesh point terminal providing IEEE 802.11-conformant wireless distribution system services to its peer EIR terminals. While different networks are designated herein, it is recognized that a single network as seen from the network layer of the Open System Interconnection (OSI) model can comprise a plurality of lower layer networks, e.g., what can be regarded as a single Internet Protocol (IP) network, can include a plurality of different physical networks. In a further aspect, the data collection system can further include a router 150 An EIR terminal 100 Under the teachings of the prior art, if the EIR terminal 100 was physically moved (e.g., by the terminal operator) from the wireless transmission range of the wireless AP or portal 140 In accordance with the one embodiment of the invention, the EIR terminal 110 always keeps its permanent IP address, so that the EIR terminal 110 can maintain all the active communication sessions using the permanent IP address when roaming between the networks 110 In one aspect, the functionality related to using a temporary IP address can be implemented in accordance with RFC 3344 by Network Working Group. An EIR terminal can have a home network whose address space can include the terminal's permanent IP address. The permanent IP address can be also referred to as a home address. In one aspect, the home network can be identified by the network part of the terminal's permanent IP address. In one embodiment, the home network can be provided by a wireless network, e.g., the wireless network 110 For example, for the EIR terminal 100 In one embodiment, a home address can be permanently assigned to an EIR terminal using a manual or an automated procedure. In another embodiment, a home address can be assigned to an EIR terminal using Dynamic Host Configuration Protocol (DHCP) upon the EIR terminal association with the home network. A skilled artisan would appreciate the fact that other ways of assigning the home address to an EIR terminal are within the scope and the spirit of the invention. The data collection system can include one or more mobility agents, including home agents and foreign agents, which facilitate the EIR terminal roaming functionality. An EIR terminal can be associated with a home agent. The home agent functionality can be provided by a router having an interface on the EIR terminal's home network. For example, an EIR terminal 110 In one aspect, a home agent can maintain current location information for a roaming EIR terminal. In one embodiment, a home agent can maintain a mobility binding table. The mobility binding table 200 can have a structure shown in In another aspect, a home agent can be adapted to forward IP datagrams addressed to a roaming EIR terminal's home address, so that the datagrams would be delivered to the roaming EIR terminal via a router having an interface on a foreign network. In one embodiment, the home agent can be adapted to perform tunneling of the IP datagrams addressed to a roaming EIR terminal, by encapsulating each IP datagram into a new IP datagram as shown in On a foreign network, the routing services to a roaming EIR terminal can be provided by a foreign agent. The foreign agent can be provided by a router having an interface on a network visited by an EIR terminal. When the EIR terminal determines that it has just moved to a new foreign network, it can acquire a new care-of address. In one embodiment, an EIR terminal can get associated with a care-of address advertised by a foreign agent. In another embodiment, an EIR terminal can acquire a care-of address via an external address assignment mechanism (e.g., DHCP; a skilled artisan would appreciate the fact that other IP address assignment mechanisms are within the scope and the spirit of the invention) and associate the acquired care-of address with one of the terminal's network interfaces (e.g., by establishing an IP alias) in order to be able to receive datagrams addressed to the care-of address. The care-of address acquired by an EIR terminal via an external address assignment mechanism is referred to as a co-located IP address. In one embodiment, the foreign agent can be adapted to receive the tunneled datagrams addressed to the care-of address, de-capsulate the original IP datagrams, look up the roaming EIR terminal by its home address in a visitor list maintained by the foreign agent, and forward them to the roaming EIR terminal using an OSI layer 2 delivery mechanism. In one embodiment, the visitor list 400 can have a structure shown in In another aspect, the foreign agent can act as a default router for the roaming EIR terminal, so that the EIR terminal would transmit outgoing IP datagrams to the foreign agent for forwarding to the respective destinations. A mobility agent can advertise its presence on a network by periodically transmitting to a broadcast or a multicast address an agent advertisement message. The agent advertisement message can contain a flag indicating whether the mobility agent transmitting the message is home or foreign agent. In one embodiment, an agent advertisement message transmitted by a foreign agent can contain one or more care-of addresses. In another aspect, an EIR terminal, instead of waiting for an agent advertisement broadcast, can transmit an agent solicitation message which can be responded to by a mobility agent. In a further aspect, an EIR terminal can determine, e.g., from an agent advertisement message that it is has just moved to another network. A skilled artisan would appreciate the fact that other ways of detecting a new network by an EIR terminal, e.g., by associating with a wireless AP or wireless portal, are within the scope and the spirit of the invention. An EIR roaming on a foreign network can register its care-of address with its home agent by transmitting a registration request message, either directly to the home agent or via a foreign agent. The registration request message can include the terminal's home address, the home agent address, and the care-of address. A skilled artisan would appreciate the fact that the registration request message can further include other fields. The home agent, upon receiving a registration request message, can add a new entry to its mobility binding table. In one embodiment, the registration request message can contain an authentication extension for authenticating a roaming EIR terminal to its home agent in order to prevent a malicious party from posing as the EIR terminal and thus attempting to intercept IP datagrams intended to be delivered to the EIR terminal. In one aspect, the authentication extension can contain a Security Parameter Index (SPI) followed by an authenticator. The SPI can contain an identifier of an algorithm (e.g., MD5) used to encrypt the authenticator. In another aspect, the authentication extension can further contain one or more unique data items designed to prevent recording and re-play by a malicious party of a valid message exchange between a roaming EIR terminal and its home agent. The unique data items can be generated using timestamps, or randomly generated numbers. A skilled artisan would appreciate the fact that other ways of authenticating a roaming EIR terminal to its home agent, and preventing message recording and re-play are within the spirit and the scope of the invention. The home agent can be adapted to intercept the datagrams sent to the EIR terminal's home address and forward the IP datagrams to the care-of address via IP encapsulation described herein supra. In a foreign agent care-of address embodiment, the IP datagrams addressed to the care-of address can be received by the foreign agent, which can de-capsulate the original IP datagrams and forward them to the roaming EIR terminal using an OSI layer 2 delivery mechanism. In a co-located care-of address embodiment, the IP datagrams addressed to the care-of address can be received by the EIR terminal itself, which then can perform the de-capsulation of the original IP datagrams. In another aspect, the wireless AP or portal 140 In one embodiment, the roaming buffer implemented by a wireless AP or portal providing home agent services for a roaming EIR terminal can extend the functionality of an IEEE 802.11-conformant power save buffer. The wireless AP providing home agent services for a roaming EIR terminal or portal can start buffering MAC frames responsive to: (a) receiving a notification from the destination EIR terminal that the EIR terminal is entering power save mode; (b) receiving a disassociation request from the destination EIR terminal; or (c) not receiving, within a pre-defined timeout, an acknowledgement from the destination EIR terminal responsive to transmitting a unicast data or control MAC frame to the EIR terminal. The wireless AP or portal providing home agent services for a roaming EIR terminal can forward one or more buffered MAC frames to the destination EIR terminal responsive to: (a) receiving a power save poll frame from the destination EIR terminal indicating that the EIR terminal is ready to receive any frames which have been buffered by the AP or portal while the terminal was in the power save mode; (b) receiving a re-association request from the destination EIR terminal; (c) receiving from the destination EIR terminal an acknowledgement for a previously transmitted unicast data or control MAC frame; or (d) receiving from the destination EIR terminal a registration request message. A skilled artisan would appreciate the fact that other types of events triggering initiating the frame buffering and forwarding buffered frames by a wireless AP or portal are within the scope and the spirit of the invention. In another embodiment, shown in The gateway router 150 A NAT table entry can comprise at least some of the fields shown in The external IP address can be used by any computer in communication with the gateway router 150 A roaming EIR terminal can be adapted to acquire (e.g., via DHCP) a new internal IP address upon associating with one of the networks 110 Upon receiving the registration request message, the gateway router 150 Since the external IP address of a roaming EIR terminal does not change, the EIR terminal 110 can maintain all the active communication sessions using the external IP address when roaming between the networks 110 In another embodiment, one external IP address can be used to route IP datagrams to and from one or more EIR terminals. This can be achieved by assigning one or more TCP/UDP port numbers to each EIR terminal in communication with one of the networks 110 In one embodiment, the address spaces of two or more local networks 110 Since the address spaces of two or more local networks 110 In another aspect, the gateway router 150 A skilled artisan would appreciate the fact that other network and transport layer protocols with acknowledgments are within the scope and the spirit of the invention. Data-link layer (OSI layer 2) behavior of a roaming EIR terminal is now being described with references to a. receive signal strength indication (RSSI) from the wireless AP or portal the EIR terminal is currently associated with, being too low; b. difference between RSSI of the wireless AP or portal the EIR terminal is currently associated with and another wireless AP or portal being larger than a pre-defined threshold; c. excessive interference or noise in the network the EIR terminal is currently associated with; d. excessive number of unsuccessful attempts to re-associate with the wireless AP or portal the EIR terminal is currently associated with; e. insufficient capacity of the wireless AP or portal the EIR terminal is currently associated with; or f. transmission errors exceeding a pre-defined threshold. A skilled artisan would appreciate the fact that other types of events triggering a roaming procedure initiation by an EIR terminal are within the scope and the spirit of the invention. In another aspect, a wireless AP or portal can be provided, e.g., by an infrastructure AP or portal, or by a mesh point terminal providing IEEE 802.11-conformant wireless distribution system services to its peer EIR terminals. In a further aspect, responsive to determining that a roaming procedure needs to be initiated, the roaming EIR terminal can disassociate with the current wireless AP or portal, by sending a Disassociate request 610, to which the current wireless AP or portal can reply by sending a Disassociate response 620. Upon disassociating with the current wireless AP or portal, the EIR terminal can send an Associate request 630 to another wireless AP or portal. The association procedure can be completed by the wireless AP or portal replying with an Associate response 640. In a further aspect, the association procedure can be followed by the EIR terminal authenticating with the new wireless AP or portal, and/or exchanging encryption keys. Now referring to attributes of EIR terminal 100 in further reference to In the embodiment of Referring to In the view of While the present invention has been particularly shown and described with reference to certain exemplary embodiments, it will be understood by one skilled in the art that various changes in detail may be affected therein without departing from the spirit and scope of the invention as defined by claims that can be supported by the written description and drawings. In particular, while the present invention has been described with reference to Internet Protocol (IP) networks, it is recognized that other network addressing schemes and standards are within the scope and the spirit of the invention. Further, where exemplary embodiments are described with reference to a certain number of elements it will be understood that the exemplary embodiments can be practiced utilizing less than the certain number of elements. A small sample of systems, apparatuses and methods described herein is as follows: A1. A portable encoded information reading (EIR) terminal for incorporation in a data collection system having a plurality of peer EIR terminals and a plurality of interconnected networks including one or more wireless networks, said EIR terminal associated with a home network having an associated address range, said home network being one of said plurality of networks, said EIR terminal configured to provide IEEE 802.11-conformant wireless distribution system services, including association, disassociation, distribution, integration, and re-association, to said peer EIR terminals, said EIR terminal comprising: a central processing unit (CPU); a memory; an encoded information reading (EIR) device selected from the group consisting of: a bar code reading device, an RFID reading device, and a card reading device, said EIR device configured to perform one of: outputting raw message data containing an encoded message, outputting decoded message data corresponding to an encoded message; at least one wireless communication interface; wherein said EIR terminal is configured, when roaming from a first network of said plurality of networks to a second network of said plurality of networks, to maintain zero or more active communication sessions with at least one remote host computer using a home address belonging to said associated address range of said home network; and wherein said EIR terminal is further configured to receive an agent advertisement message when in communication with a foreign network other than said home network, said agent advertisement message containing one or more care-of addresses. A2. The EIR terminal of A1, wherein said zero or more active communication sessions is provided by at least one active communication session including at least one message transmitted by said EIR terminal, said at least one message including decoded message data corresponding to said encoded message.
wherein second network has at least one second network wireless access device selected from the group consisting of: a wireless access point (AP), a wireless portal; and wherein said EIR terminal is further configured to disassociate with said first network and associate with said second network responsive to detection of a roaming process triggering condition selected from the group consisting of: receive signal strength indication (RSSI) of said first network wireless access device being too low; difference between RSSI of said first network wireless access device and said second network wireless access device being larger than a first pre-defined threshold; excessive interference or noise in said first network; excessive number of unsuccessful attempts to re-associate with said first network wireless access device; insufficient capacity of said first network wireless access device; and transmission errors exceeding a second pre-defined threshold. B1. A portable encoded information reading (EIR) terminal for incorporation in a data collection system having a plurality of peer EIR terminals and a plurality of interconnected networks including one or more wireless networks, said EIR terminal associated with a home network having an associated address range, said home network being one of said plurality of networks, said EIR terminal configured to be associated with a care-of address when in communication with a foreign network other than said home network, said EIR terminal configured to provide IEEE 802.11-conformant wireless distribution system services, including association, disassociation, distribution, integration, and re-association, to said peer EIR terminals, said EIR terminal comprising: a central processing unit (CPU); a memory; an encoded information reading (EIR) device selected from the group consisting of: a bar code reading device, an RFID reading device, and a card reading device, said EIR device configured to perform one of: outputting raw message data containing an encoded message, outputting decoded message data corresponding to an encoded message; at least one wireless communication interface; wherein said EIR terminal is configured, when roaming from a first network of said plurality of networks to a second network of said plurality of networks, to maintain zero or more active communication sessions with at least one remote host computer using a home address belonging to said associated address range of said home network; and wherein said EIR terminal is further configured to transmit a registration request message to one of: a home agent having a home agent address and being in communication with said home network, a foreign agent in communication with said foreign network, said registration request message including said home address, said home agent address, and said care-of address. B2. The EIR terminal of B1, wherein said zero or more active communication sessions is provided by at least one active communication session including at least one message transmitted by said EIR terminal, said at least one message including decoded message data corresponding to said encoded message.
wherein second network has at least one second network wireless access device selected from the group consisting of: a wireless access point (AP), a wireless portal; and wherein said EIR terminal is further configured to disassociate with said first network and associate with said second network responsive to detection of a roaming process triggering condition selected from the group consisting of: receive signal strength indication (RSSI) of said first network wireless access device being too low; difference between RSSI of said first network wireless access device and said second network wireless access device being larger than a first pre-defined threshold; excessive interference or noise in said first network; excessive number of unsuccessful attempts to re-associate with said first network wireless access device; insufficient capacity of said first network wireless access device; and transmission errors exceeding a second pre-defined threshold. C1. A portable encoded information reading (EIR) terminal for incorporation in a data collection system having a plurality of peer EIR terminals and a plurality of interconnected networks including one or more wireless networks, said EIR terminal associated with a home network having an associated address range, said home network being one of said plurality of networks, said EIR terminal configured to be associated with a care-of address when in communication with a foreign network other than said home network, said EIR terminal configured to provide IEEE 802.11-conformant wireless distribution system services, including association, disassociation, distribution, integration, and re-association, to said peer EIR terminals, said EIR terminal comprising: a central processing unit (CPU); a memory; an encoded information reading (EIR) device selected from the group consisting of: a bar code reading device, an RFID reading device, and a card reading device, said EIR device configured to perform one of: outputting raw message data containing an encoded message, outputting decoded message data corresponding to an encoded message; at least one wireless communication interface; wherein said EIR terminal is configured, when roaming from a first network of said plurality of networks to a second network of said plurality of networks, to maintain zero or more active communication sessions with at least one remote host computer using a home address belonging to said associated address range of said home network; and wherein said EIR terminal is further configured to receive datagrams addressed to said care-of address. C2. The EIR terminal of C1, wherein said zero or more active communication sessions is provided by at least one active communication session including at least one message transmitted by said EIR terminal, said at least one message including decoded message data corresponding to said encoded message.
wherein second network has at least one second network wireless access device selected from the group consisting of: a wireless access point (AP), a wireless portal; and wherein said EIR terminal is further configured to disassociate with said first network and associate with said second network responsive to detection of a roaming process triggering condition selected from the group consisting of: receive signal strength indication (RSSI) of said first network wireless access device being too low; difference between RSSI of said first network wireless access device and said second network wireless access device being larger than a first pre-defined threshold; excessive interference or noise in said first network; excessive number of unsuccessful attempts to re-associate with said first network wireless access device; insufficient capacity of said first network wireless access device; and transmission errors exceeding a second pre-defined threshold. D1. A data collection system comprising: a plurality of interconnected networks including one or more wireless networks; a router configured to route datagrams between said plurality of networks and at least one remote host computer; a plurality of EIR terminals, each EIR terminal associated with a home network having an associated address range, said home network being one of said plurality of networks, each EIR terminal comprising a central processing unit (CPU), a memory, at least one wireless communication interface, and an encoded information reading (EIR) device selected from the group consisting of: a bar code reading device, an RFID reading device, and a card reading device, said EIR device configured to perform one of: outputting raw message data containing an encoded message, outputting decoded message data corresponding to an encoded message; wherein at least one EIR terminal of said plurality of EIR terminals is configured to provide IEEE 802.11-conformant wireless distribution system services, including association, disassociation, distribution, integration, and re-association, to said peer EIR terminals; wherein said at least one EIR terminal is configured, when roaming from a first network of said plurality of networks to a second network of said plurality of networks, to be associated with a care-of address when in communication with a foreign network other than said home network, and to maintain zero or more active communication sessions with said at least one host computer using a home address belonging to said associated address range of said home network; and wherein said at least one EIR terminal is further configured to transmit a registration request message to one of: a home agent having a home agent address and being in communication with said home network, a foreign agent in communication with said foreign network, said registration request message including said home address, said home agent address, and said care-of address. D2. The data collection system of D1, wherein said zero or more active communication sessions is provided by at least one active communication session including at least one message transmitted by said EIR terminal, said at least one message including decoded message data corresponding to said encoded message.
wherein said foreign agent is configured, upon receiving a datagram addressed to said care-of address, to retrieve a MAC address of said EIR terminal from said visitor list and forward said datagram to said MAC address. D8. The data collection system of D1, wherein at least one network of said plurality of networks is an OSI layer 2 network.
wherein said home agent is further configured to start buffering MAC frames addressed to said at least one EIR terminal in said roaming buffer responsive to a first triggering event; and wherein said home agent is further configured to forward buffered MAC frames addressed to said at least one EIR terminal responsive to a second triggering event. D11. The data collection system of D1, wherein said first triggering event is selected from the group consisting of: receiving a notification from said at least one EIR terminal that said EIR terminal is entering a power save mode; receiving a disassociation request from said at least one EIR terminal; and not receiving, within a pre-defined timeout, an acknowledgement from said at least one EIR terminal responsive to transmitting a unicast MAC frame to said at least one EIR terminal
wherein second network has at least one second network wireless access device selected from the group consisting of: a wireless access point (AP), a wireless portal; and wherein said EIR terminal is further configured to disassociate with said first network and associate with said second network responsive to detection of a roaming process triggering condition selected from the group consisting of: receive signal strength indication (RSSI) of said first network wireless access device being too low; difference between RSSI of said first network wireless access device and said second network wireless access device being larger than a first pre-defined threshold; excessive interference or noise in said first network; excessive number of unsuccessful attempts to re-associate with said first network wireless access device; insufficient capacity of said first network wireless access device; and transmission errors exceeding a second pre-defined threshold. E1. A data collection system comprising: a plurality of interconnected networks including one or more wireless networks; a router configured to route datagrams between said plurality of networks and at least one remote host computer; a plurality of EIR terminals, each EIR terminal associated with a home network having an associated address range, said home network being one of said plurality of networks, each EIR terminal comprising a central processing unit (CPU), a memory, at least one wireless communication interface, and an encoded information reading (EIR) device selected from the group consisting of: a bar code reading device, an RFID reading device, and a card reading device, said EIR device configured to perform one of: outputting raw message data containing an encoded message, outputting decoded message data corresponding to an encoded message; wherein said at least one EIR terminal is configured, when roaming from a first network of said plurality of networks to a second network of said plurality of networks, to be associated with a care-of address when in communication with a foreign network other than said home network, and to maintain zero or more active communication sessions with said at least one host computer using a home address belonging to said associated address range of said home network; wherein said at least one EIR terminal is further configured to transmit a registration request message to one of: a home agent having a home agent address and being in communication with said home network, a foreign agent in communication with said foreign network, said registration request message including said home address, said home agent address, said care-of address; and wherein said home agent is configured to maintain a roaming buffer for buffering MAC frames addressed to said at least one EIR terminal, said home agent further configured to start buffering MAC frames addressed to said at least one EIR terminal in said roaming buffer responsive to a first triggering event, said home agent further configured to forward buffered MAC frames addressed to said at least one EIR terminal responsive to a second triggering event. E2. The data collection system of E1, wherein said first triggering event is selected from the group consisting of: receiving a notification from said at least one EIR terminal that said EIR terminal is entering a power save mode; receiving a disassociation request from said at least one EIR terminal; and not receiving, within a pre-defined timeout, an acknowledgement from said at least one EIR terminal responsive to transmitting a unicast MAC frame to said at least one EIR terminal.
a plurality of interconnected networks including one or more wireless networks; a router configured to route datagrams between said plurality of networks and at least one remote host computer; a plurality of EIR terminals, each EIR terminal comprising a central processing unit (CPU), a memory, at least one wireless communication interface, and an encoded information reading (EIR) device selected from the group consisting of: a bar code reading device, an RFID reading device, and a card reading device, said EIR device configured to perform one of: outputting raw message data containing an encoded message, outputting decoded message data corresponding to an encoded message; wherein said router is configured to maintain a network address translation (NAT) table, said NAT table comprising at least one NAT entry, said at least one NAT entry including an internal address associated with an EIR terminal of said plurality of EIR terminals; wherein said EIR terminal is further configured, when roaming from a first network of said plurality of networks to a second network of said plurality of networks, to maintain zero or more active communication sessions with said at least one host computer using an external address; and wherein said EIR terminal is configured to acquire a new internal address upon associating with a network of said plurality of interconnected networks. F2. The data collection system of F1, wherein said zero or more active communication sessions is provided by at least one active communication session including at least one message transmitted by said EIR terminal, said at least one message including decoded message data corresponding to said encoded message.
wherein said EIR terminal is further configured to transmit a registration request message to said router, said registration request message including said terminal identifier and said new internal address. F6. The data collection system of F1, wherein said EIR terminal has a terminal identifier and is associated with a home network having a home network identifier and an associated address range, and is further associated with a home address, said home network being one of said plurality of networks, said home address belonging to said associated address range of said home network, said terminal identifier provided by one of: said home address, a combination of said home address and said home network identifier, a MAC address associated with said at least one wireless communication interface, a serial number of said EIR terminal; and wherein said EIR terminal is further configured to transmit a registration request message to said router, said registration request message including said terminal identifier and said new internal address. F7. The data collection system of F1, wherein said at least one NAT entry further includes one of: an external address associated with said EIR terminal, an external port associated with said EIR terminal.
wherein said at least one NAT entry further includes said terminal identifier. F11. The data collection system of F1, wherein at least one network of said plurality of networks is an OSI layer 2 network.
wherein said gateway router is further configured to remove one or more TCP packets from said roaming buffer responsive to said at least one EIR terminal acknowledging receipt of said one or more TCP packets; and wherein said gateway router is further configured to forward buffered TCP packets addressed to said at least one EIR terminal responsive to receiving a registration request message from said at least one EIR terminal. F15. The data collection system of F1, wherein at least one said local router in communication with a local network is configured maintain a local network address translation (NAT) table, said local NAT table comprising at least one local NAT entry, said at least one local NAT entry including an internal address associated with an EIR terminal in communication with said local network.
wherein second network has at least one second network wireless access device selected from the group consisting of: a wireless access point (AP), a wireless portal; and wherein said EIR terminal is further configured to disassociate with said first network and associate with said second network responsive to detection of a roaming process triggering condition selected from the group consisting of: receive signal strength indication (RSSI) of said first network wireless access device being too low; difference between RSSI of said first network wireless access device and said second network wireless access device being larger than a first pre-defined threshold; excessive interference or noise in said first network; excessive number of unsuccessful attempts to re-associate with said first network wireless access device; insufficient capacity of said first network wireless access device; and transmission errors exceeding a second pre-defined threshold. G1. A portable encoded information reading (EIR) terminal for incorporation in a data collection system having a plurality of peer EIR terminals and a plurality of interconnected wireless networks, said EIR terminal associated with a home network having an associated address range, said home network being one of said plurality of networks, said EIR terminal comprising: a central processing unit (CPU); a memory; an encoded information reading (EIR) device selected from the group consisting of: a bar code reading device, an RFID reading device, and a card reading device, said EIR device configured to perform one of: outputting raw message data containing an encoded message, outputting decoded message data corresponding to an encoded message; at least one wireless communication interface; wherein said EIR terminal is configured, to maintain zero or more active communication sessions with at least one remote host computer when roaming from a first network of said plurality of networks to a second network of said plurality of networks, said first network having at least one first network wireless access device selected from the group consisting of: a wireless access point (AP) and a wireless portal, said second network having at least one second network wireless access device selected from the group consisting of: a wireless access point (AP) and a wireless portal; and wherein said EIR terminal is further configured to disassociate with said first network and associate with said second network responsive to detection of a roaming process triggering condition selected from the group consisting of: receive signal strength indication (RSSI) of said first network wireless access device being too low; difference between RSSI of said first network wireless access device and said second network wireless access device being larger than a first pre-defined threshold; excessive interference or noise in said first network; excessive number of unsuccessful attempts to re-associate with said first network wireless access device; insufficient capacity of said first network wireless access device; and transmission errors exceeding a second pre-defined threshold. G2. The EIR terminal of G1, wherein said zero or more active communication sessions is provided by at least one active communication session including at least one message transmitted by said EIR terminal, said at least one message including decoded message data corresponding to said encoded message.
While the present invention has been described with reference to a number of specific embodiments, it will be understood that the true spirit and scope of the invention should be determined only with respect to claims that can be supported by the present specification. Further, while in numerous cases herein wherein systems and apparatuses and methods are described as having a certain number of elements it will be understood that such systems, apparatuses and methods can be practiced with fewer than the mentioned certain number of elements. A portable encoded information reading (EIR) terminal for incorporation in a data collection system having a host computer, a plurality of peer EIR terminals, and a plurality of interconnected networks including one or more wireless networks, can comprise a central processing unit (CPU), a memory, an encoded information reading (EIR) device configured to output raw message data containing an encoded message or decoded message data corresponding to an encoded message, and at least one wireless communication interface. The EIR terminal can provide IEEE 802.11-conformant wireless distribution system services, including association, disassociation, distribution, integration, and re-association, to the peer EIR terminals. The EIR terminal can be associated with a home network and have a home address belonging to the address range associated with the home network. 1. A terminal, comprising:
a central processing unit (CPU); and an encoded information reading (EIR) device in communication with the CPU and configured for outputting data; wherein the terminal is configured for:
transmitting a registration request to a home agent, the registration request comprising a care-of address and an authentication extension for authenticating the terminal to the home agent. 2. The terminal of 3. The terminal of 4. The terminal of 5. The terminal of 6. The terminal of detecting a roaming process triggering condition; and in response to a triggering condition, disassociating with the first network and associating with the second network. 7. The terminal of a low receive signal strength indication (RSSI) of the first network; a difference between the first network's RSSI and the second network's RSSI that exceeds a first pre-defined threshold; excessive interference or noise in the first network; an excessive number of unsuccessful attempts to re-associate with the first network; insufficient capacity of the first network; and/or transmission errors exceeding a second pre-defined threshold. 8. A terminal, comprising:
a central processing unit (CPU); and an encoded information reading (EIR) device in communication with the CPU and configured for outputting data; wherein the terminal is configured for:
transmitting a registration request to a home agent or a foreign agent, the registration request comprising a care-of address and an authentication extension for authenticating the terminal to the home agent or the foreign agent, wherein the home agent has a home agent address and is in communication with a home network and the foreign agent is in communication with a foreign network; and transmitting a registration request as part of a registration request message comprising the home address and the care-of address. 9. The terminal of 10. The terminal of 11. The terminal of 12. The terminal of the first network comprises a wireless access point and/or a wireless portal; and the second network comprises a wireless access point and/or a wireless portal. 13. The terminal of detecting a roaming process triggering condition; and in response to a triggering condition, disassociating with the first network and associating with the second network. 14. The terminal of a low receive signal strength indication (RSSI) of the first network; a difference between the first network's RSSI and the second network's RSSI that exceeds a first pre-defined threshold; excessive interference or noise in the first network; an excessive number of unsuccessful attempts to re-associate with the first network; insufficient capacity of the first network; and/or transmission errors exceeding a second pre-defined threshold. 15. The terminal of 16. A terminal, comprising:
a central processing unit (CPU); and an encoded information reading (EIR) device in communication with the CPU and configured for outputting data; wherein the terminal is configured for:
transmitting an agent solicitation message; receiving an agent advertisement message comprising a care-of address; transmitting a registration request to a home agent, the registration request comprising the care-of address and an authentication extension for authenticating the terminal to the home agent; and when roaming from a first network to a second network, maintaining an active communication session with a remote host computer using a home address for addressing the terminal when providing data of an active communication session across the first network and the second network, the home address belonging to an associated address range of a home network. 17. The terminal of 18. The terminal of 19. The terminal of detecting a roaming process triggering condition; and in response to a triggering condition, disassociating with the first network and associating with the second network. 20. The terminal of a low receive signal strength indication (RSSI) of the first network; a difference between the first network's RSSI and the second network's RSSI that exceeds a first pre-defined threshold; excessive interference or noise in the first network; an excessive number of unsuccessful attempts to re-associate with the first network; insufficient capacity of the first network; and/or transmission errors exceeding a second pre-defined threshold. CROSS REFERENCE TO RELATED APPLICATIONS
FIELD OF THE INVENTION
BACKGROUND
BRIEF DESCRIPTION OF THE DRAWINGS
DETAILED DESCRIPTION
A3. The EIR terminal of A1, wherein said EIR terminal is further configured to transmit an agent solicitation message.
A4. The EIR terminal of A1, wherein at least one network of said plurality of networks is an OSI layer 2 network.
A5. The EIR terminal of A1, wherein said home address and said care-of address are Internet Protocol (IP) addresses.
A6. The EIR terminal of A1, wherein said first network has at least one first network wireless access device selected from the group consisting of: a wireless access point (AP), a wireless portal;
B3. The EIR terminal of B1, wherein said registration request message contains an authentication extension.
B4. The EIR terminal of B1, wherein at least one network of said plurality of networks is an OSI layer 2 network.
B5. The EIR terminal of B1, wherein said home address and said care-of address are Internet Protocol (IP) addresses.
B6. The EIR terminal of B1, wherein said first network has at least one first network wireless access device selected from the group consisting of: a wireless access point (AP), a wireless portal;
C3. The EIR terminal of C1, wherein at least one network of said plurality of networks is an OSI layer 2 network.
C4. The EIR terminal of C1, wherein said home address and said care-of address are Internet Protocol (IP) addresses.
C5. The EIR terminal of C1, wherein said first network has at least one first network wireless access device selected from the group consisting of: a wireless access point (AP), a wireless portal;
D3. The data collection system of D1, wherein said home agent is configured to maintain a mobility binding table containing a plurality of mobility binding entries, each mobility biding entry containing a home address, and a care-of address of an EIR terminal of said plurality of EIR terminals.
D4. The data collection system of D1, wherein said foreign agent is configured to maintain a visitor list containing a plurality of visitor list entries, each visitor entry containing a home address, a home agent address, and a MAC address of an EIR terminal of said plurality of EIR terminals.
D5. The data collection system of D1, wherein said foreign agent is configured to maintain a visitor list containing a plurality of visitor list entries, each visitor entry containing a co-located care-of address, a home agent address, and a MAC address of an EIR terminal of said plurality of EIR terminals.
D6. The data collection system of D1, wherein said home agent is configured to intercept datagrams addressed to said at least one EIR terminal and forward said intercepted datagrams to said care-of address.
D7. The data collection system of D1, wherein said foreign agent is configured to maintain a visitor list containing a plurality of visitor list entries, each visitor entry containing a home address, a home agent address, and a MAC address of an EIR terminal of said plurality of EIR terminals; and
D9. The data collection system of D1, wherein said home address, said home agent address, and said care-of address are Internet Protocol (IP) addresses.
D10. The data collection system of D1, wherein said home agent is configured to maintain a roaming buffer for buffering MAC frames addressed to said at least one EIR terminal;
D12. The data collection system of D1, wherein said second triggering event is selected from the group consisting of: receiving a power save poll frame from said at least one EIR terminal; receiving a re-association request from said at least one EIR terminal; receiving from said at least one EIR terminal an acknowledgement for a previously transmitted unicast MAC frame; receiving a registration request message from said at least one EIR terminal.
D13. The EIR terminal of D1, wherein said first network has at least one first network wireless access device selected from the group consisting of: a wireless access point (AP), a wireless portal;
E3. The data collection system of E1, wherein said second triggering event is selected from the group consisting of: receiving a power save poll frame from said at least one EIR terminal; receiving a re-association request from said at least one EIR terminal; receiving from said at least one EIR terminal an acknowledgement for a previously transmitted unicast MAC frame; receiving a registration request message from said at least one EIR terminal.
F1. A data collection system comprising:
F3. The data collection system of F1, wherein said router is further configured to intercept at least one datagram originated by said EIR terminal, said at least one datagram including a source address field, said router further configured to re-write said source address field with said external address.
F4. The data collection system of F1, wherein said router is further configured to intercept at least one datagram addressed to said EIR terminal, said at least one datagram including a destination address field, said router further configured to re-write said destination address field with said internal address.
F5. The data collection system of F1, wherein said EIR terminal has a terminal identifier and is associated with a home network having an associated address range, and is further associated with a home address, said home network being one of said plurality of networks, said home address belonging to said associated address range of said home network; and
F8. The data collection system of F1, wherein said at least one NAT entry further includes an internal port associated with said EIR terminal
F9. The data collection system of F1, wherein said EIR terminal has a terminal identifier; and wherein said at least one NAT entry further includes said terminal identifier.
F10. The data collection system of F1, wherein said EIR terminal has a terminal identifier and is associated with a home network having a home network identifier and an associated address range, and is further associated with a home address, said home network being one of said plurality of networks, said home address belonging to said associated address range of said home network, said terminal identifier provided by one of: said home address, a combination of said home address and said home network identifier, a MAC address associated with said at least one wireless communication interface, a serial number of said EIR terminal; and
F12. The data collection system of F1, wherein said internal address and said external address are Internet Protocol (IP) addresses.
F13. The data collection system of F1, wherein at least one EIR terminal of said plurality of EIR terminals is configured to provide IEEE 802.11-conformant wireless distribution system services, including association, disassociation, distribution, integration, and re-association, to said peer EIR terminals.
F14. The data collection system of F1, wherein said gateway router is further configured to maintain a roaming buffer for buffering TCP packets addressed to said at least one EIR terminal;
F16. The data collection system of F1, wherein address spaces associated with two or more said local networks at least partially overlap.
F17. The EIR terminal of F1, wherein said first network has at least one first network wireless access device selected from the group consisting of: a wireless access point (AP), a wireless portal;
G3. The EIR terminal of G1, wherein said EIR terminal configured to provide IEEE 802.11-conformant wireless distribution system services, including association, disassociation, distribution, integration, and re-association, to said peer EIR terminals.
G4. The EIR terminal of G1, wherein at least one of: said at least one home network wireless AP, said at least one foreign network wireless AP is provided by a peer EIR terminal, said peer EIR terminal said EIR terminal configured to provide IEEE 802.11-conformant wireless distribution system services, including association, disassociation, distribution, integration, and re-association.