Abstract: A great delay in communication and deterioration in quality are avoided from occurring.

Abstract: A WCDMA enabled user equipment device configured to have functions collectively or selectively idle to conserve power. A discontinuous receiver is used to detect and read network messages and report the messages to the computer within the WCDMA enabled user equipment device. The computer then activates functions previously powered down to receive incoming messages for the user of the device. The discontinuous receiver is also used when the device is active to read network messages, freeing a modem of the device to operate on user messaging; and therefore, enhancing user related performance.

Abstract: A WCDMA enabled user equipment device configured to have functions collectively or selectively idle to conserve power. A discontinuous receiver is used to detect and read network messages and report the messages to the host processor within the WCDMA enabled user equipment device. The host processor then activates functions previously powered down to receive incoming messages for the user of the WCDMA device. The discontinuous receiver is also used when the WCDMA device is active to read network messages, freeing a modem of the device to operate on user messaging; and therefore, enhancing user related performance.

Abstract: A WCDMA enabled user equipment device configured to have functions collectively or selectively idle to conserve power. A discontinuous receiver is used to detect and read network messages and report the messages to the computer within the WCDMA enabled user equipment device. The computer then activates functions previously powered down to receive incoming messages for the user of the device. The discontinuous receiver is also used when the device is active to read network messages, freeing a modem of the device to operate on user messaging; and therefore, enhancing user related performance.

Abstract: In accordance with various aspects of the present disclosure, an apparatus is disclosed that includes a sensor node configured to operate in a wireless sensor network, wherein the sensor node is configured to receive a data packet that comprises a quality of service field, examine the quality of service field, and invoke one of a plurality of pre-stored algorithms depending on the value of the quality of service field.

Abstract: A WCDMA enabled user equipment device configured to have functions collectively or selectively idle to conserve power. A discontinuous receiver is used to detect and read network messages and report the messages to the computer within the WCDMA enabled user equipment device. The computer then activates functions previously powered down to receive incoming messages for the user of the device. The discontinuous receiver is also used when the device is active to read network messages, freeing a modem of the device to operate on user messaging; and therefore, enhancing user related performance.

Abstract: A base station that communicates with subscriber stations in an OFDM wireless network. The base station transmits broadcast data and unicast data to the subscriber stations from a plurality of antennas using multiple-input, multiple-output (MIMO) techniques. The base station transmits a first broadcast pilot signal from a first antenna orthogonally to at least one of: i) a first unicast pilot signal transmitted from the first antenna; ii) a second unicast pilot signal transmitted from a second antenna; iii) a second broadcast pilot signal transmitted from the second antenna; and iv) superimposed broadcast data traffic and unicast data traffic transmitted from the first and second antennas. The base station uses orthogonal subcarriers or orthogonal time slots.

Abstract: An integrated circuit (IC) includes a processing module and main memory. The processing module includes a processing core and a first processing module millimeter wave (MMW) transceiver coupled to the processing core. The main memory includes memory and a first memory MMW transceiver coupled to the memory. At least one of an instruction and data is conveyed between the processing core and the memory via the first processing module MMW transceiver and the first memory MMW transceiver.

Abstract: A method may include establishing a first Point-to-Point Protocol (PPP) session on an interface, receiving an indication of a layer one failure, omitting for a period of time, an indication that the first PPP session on the interface is down, based on the indication of the layer one failure, establishing a layer one switchover to another interface based on the indication of the layer one failure, and attempting during the period of time, to establish a second PPP session on the other interface.

Abstract: A method for offloads SMS messages from a voice network of a wireless carrier to a data network. The method includes sending a mobile originated SMS using hypertext transfer protocol (HTTP) from a wireless handset to a short message service center (SMSC) over a wireless data network. The method further includes conducting a lookup at the SMSC to determine the home SMSC for the originating mobile handset and sending a redirect to the mobile handset as means to facilitate a dynamic update of the home SMSC location stored on the wireless handset.

Abstract: A wireless base station apparatus according to the present invention has a plurality of wireless resources allocated in correspondence with communication processings on real-time data, non-real-time data and shared data, and a control section. The control section stores a table for recording states of use of the wireless resources, and upon receiving a signal for requesting setting some of the wireless resources for new real-time data, and if no released resource is found by referring to the table, allocates part of wireless resources for communication processing on the shared data to wireless resources for communication processing on the new real-time data, and upon receiving a signal for requesting setting some of the wireless resources for new shared data, and if no released resource is found by referring to the table, allocates part of wireless resources for communication processing on the non-real-time data to wireless resources for communication processing on the new shared data.

Abstract: A Protocol for carrying Authentication for Network Access (PANA) authentication system is provided. The system includes: a PANA client (PaC) which establishes, with a PANA authentication agent (PAA), a first PANA session and a second PANA session independent of the first PANA session, and transmits, to the PAA, a PANA update request packet requesting a binding of the first PANA session and the second PANA session; and a PAA which determines whether the first PANA session and the second PANA session are associated with an identical PaC in response to the PANA update request packet received from the PaC.

Abstract: System and method for correlating multiple frames of data associated with a single call into a call record. One embodiment comprises correlating data in a radio access network by capturing data passing to and from a radio network controller, identifying ATM Adaptation Layer type 5 (AAL5) frames within the data, assigning a first call identifier to the AAL5 frames, identifying ATM Adaptation Layer type 2 (AAL2) frames within the data, assigning a second call identifier to the AAL2 frames, and combining AAL2 frames and AAL5 frames having a same first call identifier and a same second call identifier into a call record. The data passing to and from the first radio network controller may be data passing over an Iub interface between a Node B and the radio network controller or data passing over an Iur interface between two radio network controllers.

Abstract: The present invention relates to a wireless mobile communication system, and more particularly, to a method of transmitting data to mobile terminals in the wireless mobile communication system capable of transmitting multicast data. In order to solve the aforementioned problems in the prior art, a method of transmitting data to mobile terminals in a mobile terminal communicating with a network through which multicast data are transmitted. The method of the present invention comprises the steps of transmitting a requesting frame to the network for requesting the multicast data when the start of a multicast service is recognized through an upper layer of the mobile terminal; receiving a response frame from the network in response to the request frame; and receiving the multicast data from the network.

Abstract: An apparatus, a method, and logic encoded in computer readable media that when executed operable to carry out the method. The method includes wirelessly receiving at a receiving station a signal transmitted from a transmitting station in a wireless network. The signal includes a network identifier, e.g., MAC address of the transmitting station. The method includes determining one or more RF waveform characteristics of at least a transient part of the received signal, decoding the received signal to determine the network identifier, e.g., MAC address, determining one or more behavior characteristics from the received signal; and using the decoded network identifier, e.g., MAC address and a combination of the one or more waveform characteristics and the one or more behavior characteristics to ascertain whether or not the network identifier, e.g., MAC address is a spoofed identifier, the ascertaining using historical samples of combinations for different network identifiers.

Abstract: An improved connectivity to radio access point is enabled by a server that includes a database storing data about various radio access points, and an evaluation module evaluating the quality of connection to each of the access points. Clients receive updates about relevant access points from the server and use the information to connect to the preferred access point. The clients also check connectivity to other access points in the vicinity, and report the findings to the server. The server uses the reports to update its database, and send corresponding updates to the clients.

Abstract: A method for asynchronous transmission of communication data between periodically blanked terminals separated by an unknown distance is disclosed. A bursted signal is transmitted from a first terminal with a burst time tB and a burst cycle period T. The bursted signal is received at a second terminal. A bursted response signal is transmitted from the second terminal to the first terminal. The bursted response signal has a burst cycle period of T/2 and includes a pair of response bursts, with each burst in the pair having a burst time tA?T/2?tB. Each burst in the pair of response bursts carries an identical data payload. At least one of the response bursts is received at the first terminal.

Abstract: A mobile communication system includes a control device and a base station device. Data communication between the control device and the base station device is conducted using a fixed-length data size and a variable-length data size. The control device transmits information indicating whether a data size of the data communication has a fixed length or a variable length. The base station device receives the information from the control device.

Abstract: A system for providing one or more services at a network access point is described. The system comprises a controller, a wireless interface coupled with the controller, a network interface coupled with the controller, at least one of an internal interface coupled with the controller and an external interface coupled with the controller, and at least one of one or more internal modules coupled with the internal interface and one or more external modules coupled with the external interface.

Abstract: A method provides detecting a roaming operator by a mobile communications device, where the mobile communications device is associated with a home operator; receiving a data service, by the mobile communications device, provided by the roaming operator independent of the home operator; sending information, from the mobile communications device, to the roaming operator for the roaming operator to authenticate the mobile communications device with the home operator; and receiving a voice service, by the mobile communications device, provided by the roaming operator based on the authentication by the roaming operator of the mobile communications device with the home operator.

Abstract: A system and method use multiple access technologies at an access device to increase capacity and throughput. The system comprises an access device configured to communicate with a wireline switch and a wireless switch. The access device may use one or more access technologies, including digital subscriber line protocols (xDSL), multipoint multichannel distribution system (MMDS), hybrid fiber coax (HFC), satellite, and other access technologies. Preferably the access device uses inverse multiplex asynchronous transfer mode (IMA) to inversely multiplex and multiplex wireline communications and wireless communications. The wireline switch is configured to communicate with the access device using wireline communications. The wireless switch is configured to communicate with the access device using wireless communications.

Abstract: Systems and methods for providing network access to mobile devices that travel with a vehicle, such as a train, a bus, a boat, etc. along or adjacent to a relatively fixed path that may extend over a large geographic area. Mobile devices access the network through stationary access points arranged along or adjacent to the path and communicate with a communication network. The communication network may be arranged as an asynchronous transfer mode (ATM) local area network emulation (LANE) network. One of the mobile devices may be a mobile access point which can couple other mobile devices to the network and record authentication information of other mobile devices so that fast transitions can be made from one stationary access point to another as the vehicle moves along the path.

Abstract: Physical layer interface system for use in a broadband wireless access communication network is provided. The broadband wireless access communication network comprises a base station, a subscriber station and a wireless communication link for transmitting wireless communication signals upstream and downstream between the base station and the subscriber station. The physical interface system comprises a first physical layer interface for the base station for processing the communication signals upstream and downstream between the subscriber station and the base station and a second physical layer interface for processing communication signals upstream and downstream between the subscriber station and the base station. The first physical layer interface transmits downstream transmission of communication signals from the base station to the subscriber station in a burst mode.

Abstract: Disclosed herein is a method of collecting data using a Mobile Identification Number (MIN) in a Wideband Code Division Multiple Access (WCDMA) network. The method includes the steps of (a) reassembling ATM/AAL5 data into SCCP and higher layer data in an Iu-PS interface link, and capturing the reassembled data; (b) extracting SLR or DLR data from Connection Request (CR) or Connection Confirm (CC) of the captured SCCP data, and storing reference Radio Access Network Application Part (RANAP) message data having the higher layer data in storage based on the extracted SLR or DLR data; (c) extracting a mobile IP address related to the MIN of the mobile station in the Gn interface link; and (d) registering SLR or DLR data having the mobile IP address, and, afterward, capturing and extracting transmitted and received data having the SLR or DLR data in the Iu-PS interface link.

Abstract: Disclosed herein are devices and methods for communicating full-rate voice data under an ATM protocol. An exemplary device is configured to communicate voice data through a vocoder in a CDMA backbone network using an ATM Adaptation Layer 0 (AAL0) cell-generating system, which is configured to generate an AAL0 cell for each frame of full-rate voice data. In an exemplary embodiment, the device generates AAL0 cells that each comprise (a) 5 bytes of a Header field; (b) 1 byte of a Length field indicating a size of the voice data; (c) 24 bytes of a Voice-Data field containing the voice data; (d) 19 bytes of a Control-Data field containing information for controlling the voice data; (e) 1 byte of an Error-Detection field containing information for detecting an error of the voice data; and (f) 3 bytes of a PAD field for padding data used to exactly fit into the ATM cell.

Abstract: A method of configuring and registering an Internet Protocol (IPv6) address in a wireless mobile communication system having a connection-oriented radio link is provided. In an IP configuration method without Duplicate Address Detection (DAD), a Mobile Station (MS) is allocated a unique Connection Identifier (CID) specific to the MS from a serving Base Station (BS), and the MS and BS configure the IPv6 address independently using a known network prefix, a Medium Access Control (MAC) address of the MS, and the allocated CID. The BS registers the configured IPv6 address to a HA on behalf of MS.

Abstract: A wireless network apparatus and a method for controlling the transmission rate of the same, whereby a receiver side is capable of constantly maintaining the full transmission rate by coordinating the maximum number of packets to be sent to the network from a sender side. Further, a wireless network apparatus including a time interval calculating unit to calculate the time intervals of received packets, a receiving mode determining unit to determine a receiving mode to receive packets according to the calculated time intervals, a packet determining unit to calculate a period during which the determined receiving mode is maintained, and a maximum packet determining unit to determine the maximum number of packets which can be sent to the network by a device, according to the number of packets consecutively received during the calculated period.

Abstract: A base station, in a mobile communication network, includes a receive component to receive, from a higher rank station in the network, a particular data unit that includes multiple data units multiplexed together; a master processor to determine that the first portion of the particular data unit is destined for the base station and that the second portion of the particular data unit is not destined for the base station, and discard the second portion of the particular data unit; and a slave processor to determine that the second portion of the particular data unit is destined for the other base station and that the first portion of the particular data unit is not destined for the other base station, and send the second portion of the particular data unit to the other base station.

Abstract: A method and apparatus are disclosed for efficiently de-scrambling one or more bytes of data according to DSL standards on a processor. This is achieved by providing an instruction for de-scrambling one or more bytes of data according to the DSL standards. Accordingly, the invention advantageously provides a processor with the ability to de-scramble data with a single instruction thus allowing for more efficient and faster de-scrambling operations for subsequent processing.

Abstract: A method and apparatus are disclosed for efficiently de-scrambling and bit-order-reversing one or more bytes of data according to DSL standards on a processor. In a preferred embodiment, this is achieved by providing an instruction for de-scrambling and bit-order-reversing one or more bytes of data according to DSL standards. Accordingly, the invention advantageously provides a processor with the ability to de-scramble and bit-order-reverse data with a single instruction thus allowing for more efficient and faster de-scrambling operations for subsequent processing.

Abstract: A first network apparatus transmits data via a plurality of sequenced packets. A second network apparatus sets a packet holding time to be an appropriate value for every service class, and holds an earlier arriving packet up to the maximum packet holding time when an earlier transmitted packet from the first network apparatus is overtaken and a later transmitted packet arrives earlier. In addition, the second network apparatus rearranges the packets in the transmitted sequence if the overtaken packet arrives during the packet holding time, and gives up rearranging the packets in the transmitted sequence if the overtaken packet does not arrive during the packet holding time.

Abstract: A cell-based router comprising a controller to receive provisioning information including a transport rate of at least one frame-based router among a group of frame-based routers in a communication network, adjust cell transmission rate to avoid packet losses at the frame-based routers, where cell-based traffic is routed to a bidirectional cell and frame based switch according to updated bandwidth comprising the adjusted cell transmission rate, where the bidirectional cell and frame based switch is coupled to the cell-based router and the frame-based routers.

Abstract: The invention relates to communications systems, and particularly to enhancing tolerance to failures in network elements and transmission systems. The fault tolerance is achieved by providing two or more active ATM permanent virtual channel (PVC) connections between a core network element and an access network element, and providing a separate ATM interface unit for each such ATM PVC connection in the core network element. The user and signalling traffic is distributed among these active connections and interface units. In case of a failure in one of the ATM PVC connections or interface units, the communication is maintained over the other connection(s) and interface unit(s). Thus, only part of the transport capacity is lost, and a total block of communication is avoided. Any new communication will be setup over the other connections.

Abstract: A method for registering a home address of a mobile node with a home agent in a network. Instead of using the home address of the mobile node as the key element in identifying the mobile node, the home agent uses the network access identity of the mobile node included in a registration request sent by the mobile node to the home agent in the registration process. Upon receiving the registration request, the home agent authenticates the mobile node by selecting the appropriate security association based on the network access identity. In response, the home agent may send Authentication and Key material to the mobile node so as to allow the mobile node to further provide the home agent with a mobile node authentication for use in a challenge-response procedure.

Abstract: The present invention relates to a method or unifying operations of a plurality of boards in a CDMA communication system by using logical addresses of the boards. Conventionally, since a board with a physical slot ID must be attached to a slot of the system corresponding to the physical slot ID, the board cannot be recognized by the system if it is attached to another slot of the system. In the present invention, a board is attached to a slot of the system on the basis of a logical address of the board, which is stored in a board configuration information. According to the present invention, since a board can be attached to any slot of the system regardless of the physical slot ID of the board, the boards can be easily managed.

Abstract: Fast macrodiversity switching (FMS) dynamically switches radio links used for traffic and control channels for a mobile station among a number of base transceiver stations (BTS) without changing the radio resource, that is, using the same frequency and time slot combination (TDMA) or frequency and spreading code combination (CDMA). The traffic channel switching is under control of zone managers. Each BTS includes a zone manager where a host BTS has its zone manager designated as a host zone manager and other BTSs (assistant BTSs) have their zone managers designated as assistant zone managers. The control by the host and assistant zone managers includes switching down-link signals to and up-link signals from mobile stations among base transceiver stations which include broadcast channels (non-switched) and dedicated (switched) channels. Measurements of the wireless signals are made at macrodiverse locations.

Abstract: The present invention provides a VoIP wireless telephone system utilizing a wireless LAN wherein expansion of an IP wireless extension telephone is realized while ensuring secrecy of talk in a VoIP service. In the system, ID and password for connection to the Internet by PPPoE are set to a wireless LAN terminal; user authentication is executed with the above information upon connection to a BAS through a DSLAM; an ADSL modem transmits, to the BAS, IP frames received from the wireless LAN terminal; and after connection by PPPoE an IP address is given from the BAS to the wireless LAN terminal.

Abstract: A method and apparatus for packing management messages in a broadband wireless communication system. Management messages are sent across a link in packets addressed to a particular connection, where the address identifies messages which may be specially treated. Such special treatment may include recognition of an overall message conveyed in such packets as containing one or more implicit messages embedded within the overall message. Two methods are disclosed to efficiently convey such management messages. First, each packet of information sent across the link may include a message type identifier, in which case it need not be repeated in the payload of the packet, and a number of such messages may be sent within a packet. Second, a packet of information may contain mixed management messages, in which case the byte with the message type identifier should be included with each such message. In this case, an overall message may be constructed from individual management messages simply concatenated together.

Abstract: A profile for bearer data as found in IuUP and NbUP so that it can be signaled over SDP. The present invention provides AAL2 profiles that can be used to describe AAL2 bearer connections in a radio access network between a radio network controller (RNC) and a media gateway, or between two media gateways in a core network. In an embodiment, the call agent is a wireless call agent, such as a mobile switching center (MSC). The profiles provided by the present invention are used by the call agent to set up AAL2 bearer connections on the media gateway.

Abstract: A central controller (CC) [22] of a wireless Local area network (LAN) [20], in conjunction with an association operation with a mobile terminal [24] and upon receiving from the mobile terminal (MT) a first control signal [CS1] of a sequence of control signals involved in the association operation, pre-reserves a MAC resource for transmission of at least a further control signal in the sequence. The MAC resource for the further control signal is pre-reserved prior to information for the further control signal being stored in a transmission buffer [58] of the mobile terminal. In essence, judging from the nature of the first control signal, the central controller (CC) anticipates eventuality of the further control signal and pre-reserves the MAC resource for the further control signal. The central controller (CC) pre-reserves the MAC resource to avoid transmission of a separate message to request a MAC resource for the further control signal.

Abstract: A data communication network provides techniques for handling frame discard of non-delineable flows. When a data flow is established, it is evaluated to determine whether a frame delimiter value is required and, if so, whether it is present. If the frame delimiter is required and missing, then the flow is declared non-delineable. If, subsequently, a congestion threshold is reached for this data flow, cells are discarded until a) a frame delimiter value is received, b) congestion drops below the threshold or c) a predetermined number of cells are discarded. These techniques provide frame discard handling mechanisms that alleviate the need for NOC personnel to intervene in problems caused by non-delineable frame discard flows.

Abstract: A method and apparatus for packing management messages in a broadband wireless communication system. Management messages are sent across a link in packets addressed to a particular connection, where the address identifies messages which may be specially treated. Such special treatment may include recognition of an overall message conveyed in such packets as containing one or more implicit messages embedded within the overall message. Two methods are disclosed to efficiently convey such management messages. First, each packet of information sent across the link may include a message type identifier, in which case it need not be repeated in the payload of the packet, and a number of such messages may be sent within a packet. Second, a packet of information may contain mixed management messages, in which case the byte with the message type identifier should be included with each such message. In this case, an overall message may be constructed from individual management messages simply concatenated together.

Abstract: A network system includes a transmitting apparatus; a transmission path; a relaying apparatus that receives real time information transmitted through the transmission path; a wireless network; and a receiving apparatus that receives data transmitted through the wireless network. The relaying apparatus has a reference time generating part that generates a reference time independently of the transmitting apparatus; and a network transmitting part that transmits both the real time information received from the transmitting apparatus and the reference time via the wireless network.

Abstract: The fundamental idea in the invention is as follows. Instead of setting up and releasing a bearer, e.g. an AAL2 connection, the connection is maintained and only modified to have either a zero bandwidth or the required bandwidth. The zero bandwidth corresponds to a release in the conventional case and the required bandwidth corresponds to the setup of the connection. The invention is especially applicable in the cases where it is reasonable to assume that a connection once established and currently/no longer needed, that usually can be an AAL2 connection, will be needed again after a reasonably short period of time. However, the invention is applicable also in the general case where the AAL2 connections are initially set up with zero or small resources and then modified afterwards to an appropriate bandwidth on demand.

Abstract: A stream parser for receiving, parsing, and/or pre-processing network data traffic directly from an incoming unreconstructed data stream. To extract meaningful data from the unreconstructed data stream, the stream parser employs a context switch module for re-forming parts of packet headers as the data stream is streaming through the stream parser. The stream parser includes a logic unit operated by microcode stored in a program module, as well as a channel configuration memory controlled by software in a master processor. Because of this combination of hardware processing and software control, the stream parser is both quick and flexible.

Abstract: A method for ciphering MBMS (Multimedia Broadcast/Multicast Service) data in a wired/wireless communication system is provided. The MBMS service enables the same service or desired services to be provided to a number of users. In the ciphering method, a ciphering key for encoding MBMS data is previously provided to an authorized UE, and the authorized UE is informed of when MBMS data encoded using the ciphering key is to be transmitted, thereby preventing unauthorized UEs from illegally receiving the MBMS service.

Abstract: An apparatus and a method of communicating a set of user data in an ATM network-based mobile communication system are disclosed. To transmit the set of user data, N internal AAL packets are generated by adding an internal AAL packet header to each of N data subsets of an original set of user data. The internal AAL packet header includes a sequence number of each data subset. Next, one or more internal AAL cells are generated by multiplexing the internal AAL packets. Then, the original set of user data is restored by demultiplexing the internal AAL packets, included in the internal AAL cells. Thereafter, M AAL2 packets are generated by adding an AAL2 packet header to each of M data subsets of the restored set of user data. And finally, one or more AAL2 cells are generated by multiplexing the AAL2 packets. As a result, the set of user data is transmitted in the system in a much more efficient manner. Therefore, the data traffic rate in each part of the system is greatly enhanced.

Abstract: An energy efficient MAC protocol for a sensor network that extends the battery life of remotely located wireless nodes by employing MAC operations involving transmission of a wake-up signal with more processing gain, dynamic adjustment of a transmission rate of synchronization messages for fast time synchronization and an energy efficient neighboring node discovery technique.

Abstract: A wireless communications system in which real-time data and burst data can be mixedly transmitted, and a transmission band can be dynamically assigned according to a state of data transmission. A master station has a scheduler for determining a transmission band assignment including information about the transmission timing of the data, a transmission amount, and a state that is allowed to access. The scheduler regularly carries out scheduling and optimizes the transmission band to be assigned dynamically according to the communication type of the data and a state of data transmission. The master station gives a transmission band assignment which is determined by the scheduler to each slave station. A transmitting station executes data transmission (access) to a receiving station based on the given transmission band assignment. The receiving station gives information about a state of data receiving to the master station, where the scheduler reflects this on scheduling.

Abstract: The present invention is a novel method and apparatus for efficiently transporting and synchronizing data between the Media Access Control (MAC) and physical communication protocol layers in a wireless communication system. An inventive method and apparatus for transporting and synchronizing to fixed-length ATM cell boundaries and for protecting against the potential misinsertion of ATM cells has been described. An inventive ATM packet format is described. The ATM packet format is used by the present invention for the transportation and synchronization of ATM cells. The ATM packets include fields that are used to detect errors occurring within each ATM cell. ATM cells are transported in exactly two TC/PHY packets, or TDUs. ATM header information is contained in the first TDU only. No ATM header information is carried by the second TDU. An entire ATM cell is discarded if an uncorrectable error is detected in the first TDU. If no uncorrectable error occurs in the first TDU, the second TDU is checked for errors.