Method, apparatus and computer readable medium for hfn handling at inter-base station handover in mobile communication networks

Related application

This application, filed October 30, 2007, claims priority to US Provisional Application No. 60 / 983,838 entitled "HFN Handling at Inter-base Station Handover". The application has been assigned to the assignee of the present application, filed by the inventor of the present application and incorporated herein by reference.

The present disclosure relates generally to the cryptographic integrity of wireless communications, and more specifically to the handling associated with Hyper Frame Number (HFN) during inter-base station handoffs in mobile systems.

Wireless communication systems have been widely developed to provide various types of content such as voice, data and the like. These systems can be multiple access systems that can support communication with multiple users by sharing available system resources (eg, bandwidth, transmit power). Examples of such multiple access systems are code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP long term evolution (LTE) systems, and Includes orthogonal frequency division multiple access (OFDMA) systems and the like.

Generally, a wireless multiple access communication system can support communication for a plurality of wireless terminals at the same time. Each terminal can communicate with one or more base stations via transmission via forward and reverse links. A forward link (ie, downlink) refers to a communication link from a base station to a terminal, and a reverse link (ie, uplink) refers to a communication link from a terminal to a base station. This communication link may be established by a single-input single-output system, a multi-input single-output system, a multi-input multi-output (MIMO) system, or the like.

Multiple MIMO systems (N) for data transmission_T(1) transmitting antenna and multiple (N)_RUse with) receiving antennas. N_TTransmitting antennas and N_RThe MIMO channel formed by the receiving antennas is N, which is also called a spatial channel._SDivided into independent channels. Here N_S min {N_T, N_R}. N_SEach of the independent channels corresponds to a dimension. When the additional dimensions generated by multiple transmit and receive antennas are utilized, MIMO systems provide improved performance (eg, higher throughput and / or higher reliability).

MIMO systems support time division duplex (TDD) and frequency division duplex (FDD) systems. In the TDD system, the forward link transmission and the reverse link transmission are in the same frequency domain so that the forward link channel can be estimated from the reverse link channel by a mutual principle. This allows the access point to extract the transmit beamforming gain on the forward link if multiple antennas are available at the access point.

The present disclosure relates to systems and methods for managing encryption / decryption parameters during handoffs between base stations in mobile systems, as well as variants thereof.

One of the various aspects of the disclosure provides a method used for synchronization associated with a hyper frame number (HFN) between base stations during a handoff in a wireless communication system. This method uses at least the latest (latest) encrypted HFN and packet data convergence protocol (PDCP) sequence number (SN) and the latest (latest) decrypted HFN and PDCP sequence number from the source base station to the target base station. And to transfer the next PDCP sequence number to be used from the source base station to the target base station. Here, if the information of the (later) HFN and PDCP sequence number after the last (last) HFN and PDCP sequence number transmitted by the source base station is not received by the target base station, the transferred information will be used for the target. The base station will be able to provide substantial continuity of HFN and PCDP sequence numbers for terminals handing off from the source base station.

In one of the various aspects of the disclosure, the methods disclosed as described above are provided. This method also uses a backward offset from the count value used by the target base station to at least with the latest (latest) encrypted HFN and PDCP and the latest (latest) decrypted HFN and PDCP. Prepare to perform count maintenance based on.

One of the various aspects of the disclosure provides a device for synchronization associated with a hyper frame number (HFN) between base stations during a handoff in a wireless communication system. The apparatus includes a source base station, a target base station, a communication link between the source base station and the target base station, and a terminal handing off from the source base station to the target base station. The source base station travels to the target base station via a communication link, at least with the latest (latest) encrypted HFN and packet data convergence protocol (PDCP) sequence number (SN) and the latest (latest) decrypted HFN. Transfer the PDCP sequence number and the next PDCP to be used to the target base station via the communication link. Equipped with transferring SN. Here, if the information of the (later) HFN and PDCP sequence number after the last (last) HFN and PDCP sequence number transmitted by the source base station is not received by the target base station, the transferred information is used for the target. The base station will be able to provide substantial continuity of HFN and PCDP sequence numbers for terminals handing off from the source base station.

In one of the various aspects of the disclosure, the device disclosed as described above is provided. Here, by using the backward offset from the count value used by the target base station, it is based on at least the latest (latest) encrypted HFN and PDCP and the latest (latest) decrypted HFN and PDCP. Count maintenance is performed.

One of the various aspects of the disclosure provides a device used for synchronization associated with a hyper frame number (HFN) between base stations during a handoff in a wireless communication system. The device comprises a processor and memory coupled to the processor to store data. The processor, from the source base station to the target base station, at least the latest (latest) encrypted HFN and packet data convergence protocol (PDCP) sequence number (SN) and the latest (latest) decrypted HFN and PDCP sequence number. Is configured to transfer the next PDCP SN to be used from the source base station to the target base station. Here, if the information of the (later) HFN and PDCP sequence number after the last (last) HFN and PDCP sequence number transmitted by the source base station is not received by the target base station, the transferred information is used for the target. The base station will be able to provide substantial continuity of HFN and PCDP sequence numbers for terminals handing off from the source base station.

In one of the various aspects of the disclosure, the device described above is provided. Here, the processor also uses the backward offset from the count value used by the target base station to at least the latest (latest) encrypted HFN and PDCP and the latest (latest) decrypted HFN and It is configured to perform count maintenance based on the PDCP.

One of the various aspects of the disclosure provides a device used for synchronization associated with a hyper frame number (HFN) between base stations during a handoff in a wireless communication system. This device provides at least the latest (latest) encrypted HFN and packet data convergence protocol (PDCP) sequence number (SN) and the latest (latest) decrypted HFN and PDCP sequence number from the source base station to the target base station. It is provided with a means for transferring and a means for transferring the next PDCP SN to be used from the source base station to the target base station. Here, if the information of the later (later) HFN and PDCP sequence number after the last (last) HFN and PDCP sequence number transmitted by the source base station is not received by the target base station, the transferred information The target base station will be able to provide substantial continuity of HFN and PCDP sequence numbers for terminals handing off from the source base station.

In one of the various aspects of the disclosure, a computer program product comprising a computer readable medium is provided. This computer-readable medium is from the source base station to the target base station, at least the latest (latest) encrypted HFN and packet data convergence protocol (PDCP) sequence number (SN), and the latest (latest) decrypted HFN and It includes a code for transferring the PDCP sequence number and a code for transferring the next PDCP SN to be used from the source base station to the target base station. Here, if the information of the (later) HFN and PDCP sequence number after the last (last) HFN and PDCP sequence number transmitted by the source base station is not received by the target base station, the transferred information is used for the target. The base station will be able to provide substantial continuity of HFN and PCDP sequence numbers for terminals handing off from the source base station.

In one of the various aspects of the disclosure, the computer program product described above is provided. This computer program product also uses a backward offset from the count value used by the target base station to at least the latest (latest) encrypted HFN and PDCP and the latest (latest) decrypted HFN. And provides code to perform count maintenance based on PDCP.

<figref num="1">FIG. 1 illustrates a multiple access wireless communication system according to one embodiment.</figref><figref num="2">FIG. 2 is a block diagram of the communication system.</figref><figref num="3">Figure 3 is a block diagram of an encryption and decryption scheme for mobile systems.</figref><figref num="4">Figure 4 illustrates the relationship between HFN and PDCP SN.</figref><figref num="5">Figure 5 is an example of a handoff parameter between two eNBs.</figref><figref num="6A">Figure 6A is an example of an offset scheme for HFN / PDCP SN control.</figref><figref num="6B">Figure 6B is an example of an offset scheme for HFN / PDCP SN control.</figref><figref num="7">FIG. 7 is a flowchart illustrating a typical process.</figref>

Various aspects are described with reference to drawings in which the same reference numbers are used to indicate the same elements throughout. In the following description, many specific details are given to provide a complete understanding of one or more embodiments for purposes of explanation. However, it is clear that such an embodiment can be realized without these specific details. In other cases, well-known configurations and devices are shown in block diagram format to facilitate the description of one or more embodiments.

As used herein, the terms "component", "module", "system", etc. are either hardware, firmware, hardware-software combinations, software, or running software. It is intended to refer to a computer-related entity. For example, components can be, but are not limited to, processes, processors, objects, executables, threads of execution, programs, and / or computers running on the processor. By way of example, both an application running on a computer device and the computer device can be components. One or more components may exist within a process and / or execution thread, and the components may be localized to one computer and / or distributed to two or more computers. Moreover, these components are executable from different computer-readable media containing different data structures. These components (eg, data from one component that interacts with other components in a local or distributed system by signals, and / or networks such as the Internet with other systems. It can be communicated by local and / or remote processing according to a signal that has packets of one or more data (such as data from one component that interacts with other components through it).

In addition, various embodiments are described herein with respect to access terminals. Access terminals can also be systems, subscriber units, subscriber stations, mobile stations, mobiles, remote stations, remote terminals, mobile devices, user terminals, terminals, wireless communication devices, user agents, user devices, or user devices. Can also be called (UE). Access terminals can be cellular phones, cordless phones, session initialization protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), handheld devices with wireless connectivity, computer devices, or It can be another processing device that is connected to or utilizes a wireless modem. In addition, various embodiments are described herein with respect to the base station. A base station is used to communicate with an access terminal and may also be referred to as an access point, node B, e-node B (eNB), or some other terminology. Depending on the context of the description provided below, the term node B may be replaced by eNB and vice versa, depending on the relevant communication system applied.

In addition, the various aspects or features described herein can be realized as methods, devices, or manufactured articles using standard programming and / or engineering techniques. As used herein, the term "manufactured article" is intended to include a computer program accessible from any computer-readable device, carrier, or medium. For example, computer-readable media are, but are not limited to, magnetic storage devices (eg, hard disks, floppy (registered trademark) disks, magnetic strips, etc.), optical disks (eg, compact discs (CDs), DVDs, etc.). Etc.), smart cards, and flash memory devices (eg EPROMs, cards, sticks, key drives, etc.). In addition, the various storage media described herein can represent one or more devices for storing information, and / or other machine-readable media. The term "machine readable medium" may include, without limitation, radio channels and any other medium capable of storing, including, and / or carrying instructions and / or data.

The techniques described herein include, for example, code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal frequency division multiple access (OFDMA) networks, singles. It is used for various wireless communication networks such as carrier FDMA (SC-FDMA) networks. The terms "system" and "network" are often used interchangeably. CDMA networks can implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc., for example. UTRA includes wideband CDMA (W-CDMA) and low chip rate (LCR). cdma2000 covers the IS-2000, IS-95, and IS-856 standards. The TDMA network can implement radio technologies such as, for example, the Global Mobile Communication System (GSM). OFDMA networks include, for example, Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE. Radio technologies such as 802.20, Flash OFDM®, etc. can be implemented. UTRA, E-UTRA, and GSM are part of the Universal Mobile Telecommunications System (UMTS). Long Term Evolution (LTE) is the latest release of UMTS using E-UTRA. UTRA, E-UTRA, GSM, UMTS, and LTE are listed in documents from an organization named "3rd Generation Partnership Program" (3GPP). cdma2000 is described in a document from an organization named "3rd Generation Partnership Plan 2" (3GPP2). These various radio technologies and standards are known in the art. For clarification, some aspects of these techniques will be described below with respect to LTE. And LTE terminology is used in most of the following descriptions.

Single Carrier Frequency Division Multiple Access (SC-FDMA) is a communication technology that uses single carrier modulation and frequency domain equalization. SC-FDMA has substantially the same complexity and comparable performance as an OFDMA system. The SC-FDMA signal has a low peak-to-average power ratio (PAPR) due to its unique single carrier structure. SC-FDMA has received a great deal of attention, especially in uplink communications, where low PAPR is of great benefit to mobile terminals in terms of transmission power efficiency. It is currently hypothesized to be operating for an uplink multiple access scheme in 3GPP Long Term Evolution (LTE) or Evolved UTRA.

As shown in FIG. 1, a multiple access wireless communication system according to one embodiment is exemplified. Access point 100 (AP), also known as enode B or eNB, contains multiple antenna groups, one containing 104 and 106, another containing 108 and 110, and yet another. Contains 112 and 114. In Figure 1, only two antennas are shown for each antenna group. However, for each antenna group, more or less than two antennas may also be used. The access terminal 116 (AT), which is also called a user device (UE), communicates with the antennas 112 and 114, and the antennas 112 and 114 transmit information to the access terminal 116 by the forward link 120 and the reverse link. Receive information from the access terminal 116 at 118. The access terminal 122 communicates with the antennas 106 and 108, and the antennas 106 and 108 transmit information to the access terminal 122 by the forward link 126 and receive information from the access terminal 122 by the reverse link 124. In FDD systems, communication links 118, 120, 124, 126 may use different frequencies for communication. For example, the forward link 120 may use a different frequency than that used by the reverse link 118.

Each group of areas and / or antennas designed to communicate is often referred to as the access point sector. In embodiments, each antenna group is designed to communicate with access terminals within a sector of the area covered by the access point 100.

In communication over forward links 120, 126, the transmitting antenna at access point 100 utilizes beamforming to improve the signal-to-noise ratio of forward links for different access terminals 116, 124. In addition, access points that use beamforming to transmit to randomly scattered access terminals over the coverage area have access within neighboring cells rather than access points that transmit to all access terminals with a single antenna. It causes little interference with the terminal.

An access point is a fixed station used to communicate with a terminal and may also be referred to as an access point, node B, or some other terminology. Access terminals can also be referred to by access terminals, user devices (UEs), wireless communication devices, terminals, access terminals, or some other terminology.

FIG. 2 is a block diagram of an embodiment of a transmitter system 210 (also known as an access point) and a receiver system 250 (also known as an access terminal) in MIMO system 200. In the transmitter system 210, the traffic data of many data streams is provided from the data source 212 to the transmitter (TX) data processor 214.

In an embodiment, each data stream is transmitted through its respective transmitting antenna. The TX data processor 214 formats the traffic data for each data stream, encodes, interleaves, and encodes the data based on the specific encoding scheme selected for this data stream. I will provide a.

The encoded data in each data stream can be multiplexed with pilot data using OFDM technology. Pilot data is generally a known data pattern that is processed in a known way and can be used in the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is based on the specific modulation scheme selected for the data stream (eg, BPSK, QPSK, M-PSK, or M-QAM). Is modulated (eg, symbol-mapped) to provide modulated symbols. The data rate, coding, and modulation of each data stream can be determined by a set of instructions executed by processor 230. Memory 232 can be coupled to processor 230.

Modulation symbols for all data streams are provided to the TX MIMO processor 220, which processes the modulation symbols (eg, for OFDM). The TX MIMO processor 220 then N_TN modulation symbol streams_TProvided to a number of transmitters (TMTR) 222a-222t. In one embodiment, the TX MIMO processor 220 applies beamforming weights to a symbol of the data stream and to the antenna on which the symbol is transmitted.

Each transmitter 222a-222t receives and processes its respective symbol stream to provide one or more analog signals, and further provides a suitable modulated signal for transmission over MIMO channels. To do this, adjust (eg, amplify, filter, and upconvert) this analog signal. In addition, N from transmitters 222a-222t_TThe number of modulated signals is N_TIt is transmitted from each of the antennas 224a to 224t.

In receiver system 250, the transmitted modulated signal is N_RReceived by the antennas 252a to 252r, the received signal from each of the antennas 252a to 252r is provided to the respective receivers (RCVR) 254a to 254r. Each receiver 254a-254r tunes (eg, filters, amplifies, and downconverts) each received signal, digitizes the tuned signal to provide a sample, and further processes this sample. Provides the corresponding "received" symbol stream.

RX data processor 260 is N_RN from receivers 254a to 254r_RReceive N symbol streams and process these received symbol streams based on specific receiver processing techniques._TProvides a stream of "detected" symbols. The RX data processor 260 demodulates, deinterleaves, and decodes each detected symbol stream to restore the traffic data for this data stream. The processing by the RX data processor 260 is complementary to that performed by the TX MIMO processor 220 and the TX data processor 214 in the transmitter system 210.

Processor 270 periodically determines which precoded matrix to use, as described above. Further, the processor 270 can specify a reverse link message having a matrix index part and a rank value part. Memory 272 is coupled to processor 270.

Reverse link messages can contain different types of information about communication links and / or received data streams. The reverse link message is processed by the TX data processor 238, which receives the traffic data of many data streams from the data source 236, modulated by the modulator 280, tuned by the transmitters 254a-254r, and the base station. Send back to 210.

In transmitter system 210, the modulated signal from receiver system 250 is received by antennas 224a-224t, tuned by receivers 222a-222t, demodulated by demodulator 240, processed by RX data processor 242, and processed. Extract the reverse link message sent by receiver system 250. In addition, processor 230 processes this extracted message to determine which pre-coded matrix to use to determine the beamforming weights.

In aspects, logical channels are classified into control channels and traffic channels. The logical control channel includes: A broadcast control channel (BCCH), which is a DL channel for broadcasting system control information. A paging control channel (PCCH), which is a DL channel that transfers paging information. Multicast Control Channel (MCCH), a point-to-multicast DL channel used to send multimedia broadcast and multicast service (MBMS) schedule and control information for one or several MTCHs. Generally, after establishing an RRC connection, this channel is only used by UEs that receive MBMS (Note: Old MCCH + MSCH). A dedicated control channel (DCCH) is a point-to-point bidirectional channel that transmits dedicated control information and is used by UEs with RRC connections. In aspects, the logical traffic channel comprises: A dedicated traffic channel (DTCH), which is a point-to-point bidirectional channel dedicated to a single UE for transferring user information. Multicast traffic channel (MTCH) for point-to-multipoint DL channels for sending traffic data.

In aspects, transmission channels are classified into DL and UL. DL transmission channels include broadcast channels (BCH), downlink shared data channels (DL-SDCH), and paging channels (PCH). PCH supports UE power savings by being broadcast throughout the cell and mapped to PHY resources used for other control / traffic channels (eg, DRX cycles are shown to the UE by the network). Uru etc.). UL transmission channels include random access channels (RACH), request channels (REQCH), uplink shared data channels (UL-SDCH), and multiple PHY channels. The PHY channel comprises a set of DL and UL channels.

The DL PHY channel comprises: Common Pilot Channel (CPICH), Synchronous channel (SCH), Common Control Channel (CCCH), Shared DL Control Channel (SDCCH), Multicast Control Channel (MCCH), Shared UL Allocation Channel (SUACH), Acknowledgment Channel (ACKCH), DL Physical Shared Data Channel (DL-PSDCH), UL Power Control Channel (UPCCH), Paging Indicator Channel (PICH), Load indicator channel (LICH). UL PHY channels include: Physical Random Access Channel (PRACH), Channel Quality Indicator Channel (CQICH), Acknowledgment Channel (ACKCH), Antenna Subset Indicator Channel (ASICH), Shared request channel (SREQCH), UL Physical Shared Data Channel (UL-PSDCH), Broadcast pilot channel (BPICH).

In aspects, a channel structure is provided that maintains the low PAR characteristics of a single carrier waveform (channels are adjacent in frequency or arranged at regular intervals at a given time).

The following abbreviations apply for the purposes of this document. AM: Acknowledgment mode. AMD: Acknowledgment mode data. ARQ: Automatic repeat request. BCCH: Broadcast control channel. BCH: Broadcast channel. C-: Control-. CCCH: Common control channel. CCH: Control channel. CCTrCH: Encoded synthetic transmission channel. CP: Cyclic prefix. CRC: Cyclic redundancy check. CTCH: Common traffic channel. DCCH: Dedicated control channel. DCH: Dedicated channel. DL: Downlink. DSCH: Downlink shared channel. DTCH: Dedicated traffic channel. FACH: Forward link access channel. FDD: Frequency Division Duplex. L1: Layer 1 (physical layer). L2: Layer 2 (data link layer). L3: Layer 3 (network layer). LI: Length indicator. LSB: The least significant bit. MAC: Medium access control. MBMS: Multimedia broadcast multicast service. MCCH: MBMS point-to-multipoint control channel. MRW: Motion reception window. MSB: Most significant bit. MSCH: MBMS point-to-multipoint scheduling channel. MTCH: MBMS point-to-multipoint traffic channel. PCCH: Paging control channel. PCH: Paging channel. PDU: Protocol data unit. PHY: Physical layer. PhyCH: Physical channel. RACH: Random access channel. RLC: Wireless link control. RRC: Radio resource control. SAP: Service Access Point.

SDU: Service data unit. SHCCH: Shared channel control channel. SN: Sequence number. SUFI: Super field. TCH: Traffic channel. TDD: Time division duplex. TFI: Transmission format indicator. TM: Transparent mode. TMD: Transparent mode data. TTI: Transmission time interval. U-: User-. UE: User device. UL: Uplink. UM: Non-acknowledgement mode. UMD: Non-acknowledged mode data. UMTS: Universal mobile communication system. UTRA: UMTS Terrestrial Radio Access. UTRAN: UMTS Terrestrial Radio Access Network. MBSFN: Multicast broadcast single frequency network. MCE: MBMS coordination entity. MCH: Multicast channel. DL-SCH: Downlink shared channel. MSCH: MBMS control channel. PDCCH: Physical downlink control channel. PDSCH: Physical downlink shared channel. eNB: Base station or base transceiver station. PDCP: Packet data convergence protocol. HFN: Hyper frame number.

FIG. 3 is a block diagram 300 illustrating an encryption and decryption scheme suitable for use in mobile systems. The above figure shows the general teaching of the encryption procedure in eNB. Here, the data 310 is combined with a cipher containing the HFN 320 and the Packet Convergence Protocol (PDCP) Layer Sequence Number (SN) 33 and is combined with the encryption key 340 using the encryption algorithm 350, thereby the UE. Encrypted data 360 to be transferred to is generated.

The lower figure illustrates a general decoding procedure in the UE. Here, the received encrypted data 360 is combined with PDCP SN330 and HFN320 (acquired or generated at initialization / startup in the UE) to perform encryption key 340 (often referred to as security key) and decryption algorithm 370. Decrypted using, which regenerates the original data 310. Figure 3 is understood to provide a general overview of using the HFN320 and PDCP SN330 for encryption / decryption. Further factors or factors relating to encryption / decryption are beyond the scope of understanding the various embodiments disclosed herein and will not be described in further detail.

It is understood that in cryptography, security can be enhanced by combining data with large sets that increase the number of possible combinations. In the mobile community, this large set has HFN and PDCP SN and is referred to as cryptosync, which is continuously ordered by incrementing the value of PDCP SN. Increment gives the order or array of HFN / PDCP SN values and guarantees that the cryptosync for each set of encrypted / decrypted packets will change. cryptosync shows a large value, and since this value changes (depending on the PDCP SN array), a certain amount of randomness will be introduced, resulting in a more robust encryption scheme. However, this robustness assumes that the same HFN / PDCP SN sequence will not be used again for a given key. This is because cryptographic methods that repeatedly use "encoding elements" are known to be more vulnerable to cracks.

FIG. 4 is an example 400 showing the relationship between HFN and PDCP SN. The PDCP SN is a fixed bit counter, as shown as a 12-bit counter in Figure 4. In various implementations, the PDCP SN can be a 5-bit counter, a 7-bit counter, a 12-bit counter, or any other size counter, so the PDCP SN is used in the 12-bit implementations shown here. It should be noted that it is not limited. The PDCP SN acts as a circular counter that "resets" itself and rolls over to the previous start value. For example, a PDCP SN (using 12 bits) has a decimal range of 1 to 4096 (or 0 to 4095). Using this range from 0 to 4095, the value 4096 is equivalent to 0. Similarly, the value 4097 is equivalent to 1 and the value 4098 is equivalent to 2. Therefore, a PDCP SN with a value of 1 is equivalent to a rolled-over value such as 4097, 8193, 12,289. PDCP The HFN can be used as a counter to track the number of "rollovers" of SNs. Therefore, if the PDCP SN is rolled over 4 times, the HFN will show a value of 4 on the right side (in some cases, the HFN can reserve higher bits for other information). .. As is clear, there can be significantly larger numbers that can be obtained by the HFN / PCDP SN combination.

As shown in FIG. 3, the decryption algorithm 370 requires that the PDCP SN and HFN values be the same as those used in the encryption algorithm 360. Therefore, it is important that the decrypting entity (receiving terminal) correctly obtains the same PDCP SN and HFN values used by the cryptographic entity (transmitting station). During a handoff between two transmitters, the target transmitter may not receive the correct sequence PCDP SN / HFN value from the source transmitter. In order to avoid this, it has been proposed that the HFN used by the target transmitter is reset to zero at the time of handover while the PDCP sequence is maintained, and the key change at the time of handover is requested. However, this approach offers the possibility that the HFN value will be reset "prematurely". That is, the entire range of HFN values is not fully utilized before it is reset to zero at handoff, thus effectively negating the "large" cryptosync contribution to the cryptographic algorithm. What is desired is PDCP with a wide range of HFN / PDCP SN values. It would be a scheme to avoid ambiguity from SN rollover.

Figure 5 is an example 500 of handoff parameters between two eNBs according to a typical approach in which HFN is also retained during movement. In this embodiment, the HFN does not need to be reset (thus the key does not need to be changed during handover). If the source transmitter 510 sends the encrypted data over link 515 and the receiver 520 (UE) is handing off to the target transmitter 530, then "next PDCP SN to use", The following is transferred from the source eNB 510 to the target eNB 530 via the communication line X2 (540). The latest HFN and PDCP SN used for encryption in the source eNB 510. The latest HFN and PDCP SN used for decoding in the source eNB 510.

For DL encryption, the target eNB530 is the normal count for encryption based on the PDCP SDU SN to be transmitted and the latest (latest) HFN and PCDP SN transferred for encryption. -Maintenance can be performed. The term count can represent the set of HFN and PDCP SN. The following is an example for DL encryption according to a typical embodiment as illustrated in FIG.

Source eNB510 uses HFN value = x at PDCP SN value = 4093 for pre-handover encryption. This combination can be symbolized by equation (x || 4093). During the handover, the source eNB 510 transfers the current HFN value = x and the current PDCP SN value 4093 (ie x || 4093) to the target eNB 530, and the "next PDCP SN = 2 to use" also goes to the target eNB 530. Forward. The source eNB530 also forwards the PDCP PDUs of SN4094, 4095, 0, 1 to the target eNB530.

At the time of handover, the target eNB 530 transmits the following to the UE 520. x || 4094, x || 4095, (x + 1) || 0 (count maintenance requires increment of HFN), (x + 1) || 1, and (x + 1) || 2 ..

If PDCP SN = 4094 and PDCP SN = 4095 are lost at data link X2 (540) to target eNB 530 when receiving the starting PDCP SN value = 4093 and the next PDCP SN = 2 to be used from the source eNB 510. Even so, the target eNB530 will know when to increment the HFN because it knows that the last PDCP SN reported by the source eNB510 is 4093. Therefore, as seen at link 535, the target eNB530 forwards the correct sequence of encrypting / decrypting the HFN / PDCP SN value to the UE520.

Therefore, the possibility that the source eNB and the target eNB lose synchronization during the handoff eliminates the need to force a reset of the HFN and / or PDCP SN values during the handoff. In addition, this scheme allows a wider range of HFN and / or PDCP SN values to be utilized.

Based on the above description, UL deciphering the procedure will adapt appropriately and follow the same. Since this is within the understanding of those skilled in the art, the details of the UE procedure are generally redundant and will not be discussed in further detail.

6A-6B are examples of offset schemes for HFN / PDCP SN control. If the UE is only communicating with the base station for a long period of time, the combination of HFN and PDCP SN can extend to a full cycle. That is, cryptosync (or, in some cases, called a count) overflows and starts at zero. Alternatively, that particular practice forces a reset to zero. In a typical system, to avoid reuse of the count = 0 value, there is a threshold as to which key will be changed if the count reaches or exceeds the threshold. The value can be used. This scenario is illustrated in Figure 6A.

However, as described in the typical embodiment above, the need for threshold triggers is less clear when it is assumed that the HFN is preserved in the inter-eNB handover. Specifically, count wraparound does not necessarily mean that the life of the key has expired. This is because the eNB key is changed during the inter-eNB handover, and the count value starts from an arbitrary value.

Figure 6B illustrates a typical approach based on the above description. Assuming that the first key, the new key, is generated at the start or at the first handoff, the count value continues in the next or next provided sequence (according to the embodiment described above). , And then increment past the count = 0 value and continue. At a trigger value prior to the handoff value specified by the backward offset (or forward offset, depending on the practice choice) from the handoff point, the key expires and a new key is released. Will be generated. If desired, the offset can depend on some network parameters.

It is understood that the network can apply a backward offset from the initial count value as shown in Figure 6B. It should be noted that the above key lifetime handling is required for each radio bearer using RLC-AM in the network and can be found to be available in E-UTRAN. The typical handling of counts requires standardization and can be completely transparent to the UE. The UE specification allows wraparound of count values, but the UE does not need to be aware of possible reuse of count values. Appropriate actions (ie, rekeying) can be taken depending on the network to avoid reusing the count value for the same key. This approach has the following advantages: -No need to standardize network behavior. -No over-the-air signaling. -Key life maintenance is completely transparent to the UE.

It should be noted that this solution is some network internal behavior or variants thereof, such as: However, the typical methods and systems disclosed herein demonstrate the benefits believed to justify changing the complexity of the network.

FIG. 7 is a flowchart illustrating a typical process 700 that provides an embodiment of this disclosure. After start 710, this typical process 700 begins with a notification that a handoff is imminent (720). Prior to the handoff, the source station sends the required HFN and next PDCP SN number to the target station (730). When the target station receives the appropriate information, it takes over the decryption / encryption control for the UE (740). After the handoff, this typical process 700 optionally initiates a backward offset to the count according to the scheme described in Figure 6 (750). This typical operation ends when step 740 or optional step 750 is completed (760).

It is understood that the specific order or hierarchy of the disclosed processing steps is an example of a typical approach. Based on the design choices, it is understood that the specific order or hierarchy of steps in these processes will be rearranged while maintaining the scope of the present disclosure. The accompanying method claims represent elements in the various steps of the sample order and are not meant to be limited to the specific order or hierarchy shown.

Those skilled in the art will further appreciate the various exemplary logic blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein, in electronic engineering hardware, computer-readable media. You will understand that it is realized as computer software, including computer programs in the form of, or a combination thereof. To articulate the interstitial nature of hardware and software, various exemplary components, blocks, modules, circuits, and steps have been generally described in terms of their functionality. Whether these functions are realized as hardware or software depends on the design constraints imposed on specific applications and the entire system. Those skilled in the art can realize the above-mentioned functions in a manner that changes according to each specific application. However, this application decision should not be construed as causing a deviation from the scope of the invention.

The various exemplary logic blocks, modules, and circuits described in connection with the embodiments disclosed herein include general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), and fields. A programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination of the above designed to achieve the functions described above. Can be realized or implemented using. Although it is possible to use a microprocessor as a general-purpose processor, it is also possible to use a conventional processor, controller, microcontroller, or state device instead. The processor can also be implemented, for example, as a combination of DSP and microprocessor, multiple microprocessors, one or more microprocessors working with a DSP core, or any other combination of computing devices of this configuration. is there.

The above includes an example of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methodologies for the purposes of describing the embodiments described above, but those skilled in the art will appreciate many more combinations of the various embodiments. And can recognize that it can be replaced. Accordingly, the described embodiments are intended to include all such modifications, modifications, and modifications that fall within the spirit and scope of the claims. Moreover, as long as the term "contains" is used either in the detailed description or in the claims, such term shall be interpreted as the term "provide" when applied as a transitional term in the claims. Similarly, it is intended to be inclusive.

The above description of the disclosed embodiments will be provided to those skilled in the art to enable the manufacture or use of the present disclosure. Various variations on these embodiments are also apparent to those of skill in the art, and the general principles defined herein apply to other examples without departing from the gist or scope of the present disclosure. Can be done. As such, the invention is not limited to the embodiments presented herein, but is intended to correspond to the broadest scope consistent with the principles and novel features disclosed herein. ing.<u style="single">In addition, the invention described in the claims at the time of filing is added below.</u><u style="single">[Invention 1]</u><u style="single">A method used for synchronization related to hyper frame number (HFN) between base stations during handoff in wireless communication systems.</u><u style="single">Transfer at least the latest (latest) encrypted HFN and packet data convergence protocol (PDCP) sequence number (SN) and the latest (latest) decrypted HFN and PDCP sequence number from the source base station to the target base station. That and</u><u style="single">It comprises transferring the next PDCP sequence number to be used from the source base station to the target base station.</u><u style="single">If the information of the (later) HFN and PDCP sequence number after the last (last) HFN and PDCP sequence number transmitted by the source base station is not received by the target base station, the transferred information will cause the said. A method by which a target base station can provide substantial continuity of HFN and PCDP sequence numbers for terminals handing off from said source base station.</u><u style="single">[Invention 2]</u><u style="single">The method according to Invention 1, wherein the source base station and the target base station are e-node B.</u><u style="single">[Invention 3]</u><u style="single">By using the backward offset from the count value used by the target base station, at least based on the latest (latest) encrypted HFN and PDCP and the latest (latest) decrypted HFN and PDCP. The method according to invention 1, further comprising performing count maintenance.</u><u style="single">[Invention 4]</u><u style="single">The method according to invention 3, wherein the HFN value and the PDCP value are not required to be reset at the time of handoff.</u><u style="single">[Invention 5]</u><u style="single">The method according to Invention 3, wherein a new key is generated at the time of handoff.</u><u style="single">[Invention 6]</u><u style="single">The method according to Invention 3, which does not require over-the-air signaling during handoff.</u><u style="single">[Invention 7]</u><u style="single">The method according to Invention 3, wherein the key life maintenance for the terminal is transparent.</u><u style="single">[Invention 8]</u><u style="single">A device for synchronization related to the Hyper Frame Number (HFN) between base stations during a handoff in a wireless communication system.</u><u style="single">With the source base station</u><u style="single">With the target base station</u><u style="single">A communication link between the source base station and the target base station,</u><u style="single">It includes a terminal handing off from the source base station to the target base station.</u><u style="single">The source base station delivers at least the latest (latest) encrypted HFN and packet data convergence protocol (PDCP) sequence number (SN) and the latest (latest) decryption to the target base station via the communication link. The next PDCP to be used that transfers the HFN and PDCP sequence number to the target base station via the communication link.</u><u style="single">Transfer SN,</u><u style="single">If the information of the (later) HFN and PDCP sequence number after the last (last) HFN and PDCP sequence number transmitted by the source base station is not received by the target base station, the transferred information will cause the said. A target base station is a device capable of providing substantial continuity of HFN and PCDP sequence numbers for a terminal handed off from the source base station.</u><u style="single">[Invention 9]</u><u style="single">The device according to the invention 8, wherein the source base station and the target base station are e-node B.</u><u style="single">[Invention 10]</u><u style="single">By using the backward offset from the count value used by the target base station, at least based on the latest (latest) encrypted HFN and PDCP and the latest (latest) decrypted HFN and PDCP. The device according to Invention 8, wherein count maintenance is performed.</u><u style="single">[Invention 11]</u><u style="single">The device according to invention 8, wherein the HFN value and the PDCP value are not required to be reset at the time of handoff.</u><u style="single">[Invention 12]</u><u style="single">The device according to invention 10, wherein a new key is generated at the time of handoff.</u><u style="single">[Invention 13]</u><u style="single">The device according to invention 10, wherein over-the-air signaling is not required during handoff.</u><u style="single">[Invention 14]</u><u style="single">The device according to the invention 10, wherein the key life maintenance for the terminal is transparent.</u><u style="single">[Invention 15]</u><u style="single">A device used for synchronization related to Hyper Frame Number (HFN) between base stations during handoff in a wireless communication system.</u><u style="single">It comprises a processor and a memory coupled to the processor to store data.</u><u style="single">The processor, from the source base station to the target base station, at least the latest (latest) encrypted HFN and packet data convergence protocol (PDCP) sequence number (SN) and the latest (latest) decrypted HFN and PDCP sequence number. And is configured to transfer the next PDCP sequence number to be used from the source base station to the target base station.</u><u style="single">If the information of the (later) HFN and PDCP sequence number after the last (last) HFN and PDCP sequence number transmitted by the source base station is not received by the target base station, the transferred information will cause the said. A target base station is a device capable of providing substantial continuity of HFN and PCDP sequence numbers for a terminal handed off from the source base station.</u><u style="single">[Invention 16]</u><u style="single">The processor further uses a backward offset from the count value used by the target base station to at least the latest (latest) encrypted HFN and PDCP and the latest (latest) decrypted HFN and PDCP. The device according to invention 15, configured to perform count maintenance based on.</u><u style="single">[Invention 17]</u><u style="single">A device used for synchronization related to Hyper Frame Number (HFN) between base stations during handoff in a wireless communication system.</u><u style="single">Transfer at least the latest (latest) encrypted HFN and packet data convergence protocol (PDCP) sequence number (SN) and the latest (latest) decrypted HFN and PDCP sequence number from the source base station to the target base station. Means and</u><u style="single">A means for transferring the next PDCP sequence number to be used from the source base station to the target base station is provided.</u><u style="single">If the information of the (later) HFN and PDCP sequence number after the last (last) HFN and PDCP sequence number transmitted by the source base station is not received by the target base station, the transferred information will cause the said. A target base station is a device capable of providing substantial continuity of HFN and PCDP sequence numbers for a terminal handed off from the source base station.</u><u style="single">[Invention 18]</u><u style="single">A computer program product with a computer-readable medium</u><u style="single">The computer-readable medium is</u><u style="single">From the source base station to the target base station, at least the latest (latest) encrypted hyper frame number (HFN) and packet data convergence protocol (PDCP) sequence number (SN), and the latest (latest) decryption HFN and PDCP. The code for transferring the sequence number and</u><u style="single">A code for transferring the next PDCP sequence number to be used from the source base station to the target base station is provided.</u><u style="single">If the information of the (later) HFN and PDCP sequence number after the last (last) HFN and PDCP sequence number transmitted by the source base station is not received by the target base station, the transferred information will cause the said. A target base station is a computer program product capable of providing substantial continuity of HFN and PCDP sequence numbers for a terminal handed off from said source base station.</u><u style="single">[Invention 19]</u><u style="single">By using the backward offset from the count value used by the target base station, at least based on the latest (latest) encrypted HFN and PDCP and the latest (latest) decrypted HFN and PDCP. The computer program product according to Invention 18, further comprising code for performing count maintenance.</u><u style="single">[Invention 20]</u><u style="single">The computer program product according to Invention 18, further comprising a code such that the HFN value and the PDCP value do not need to be reset at handoff.</u>