WO2014179981A1

WO2014179981A1 - User equipment triggered switch-back to wireless wide area network after offload

Info

Publication number: WO2014179981A1
Application number: PCT/CN2013/075456
Authority: WO
Inventors: Wei Hong; Jari Jaakko ISOKANGAS; Na WEI; Erlin Zeng; Haiming Wang
Original assignee: Broadcom Corporation
Priority date: 2013-05-10
Filing date: 2013-05-10
Publication date: 2014-11-13

Abstract

While a user equipment (UE) is attached to a wireless wide area network and operating on a wireless local area network for offloading traffic from the wireless wide area network, the UE initiates a switch back to the wireless wide area network from the wireless local area network and indicates to the wireless wide area network, via wireless signaling during a connection establishment or connection reestablishment or connection reconfiguration procedure, that the UE is switching back from the wireless local area network to the wireless wide area network. In several but not all embodiments the connection establishment procedure is a random access procedure and the wireless signaling indicating that the UE is switching back comprises a random access sequence reserved for UE switch back purposes.

Description

USER EQUIPMENT TRIGGERED SWITCH-BACK TO

WIRELESS WIDE AREA NETWORK AFTER OFFLOAD

TECHNICAL FIELD:

[0001 ] The exemplary and non-limiting embodiments of this invention relate generally to wireless communication systems, methods, devices and computer programs and, more specifically, relate to connection establishment and related signaling for a user equipment returning to a wireless wide area network after being offloaded to a wireless local area network.

BACKGROUND:

[0002] There has been much research recently into offloading user equipment (UE) traffic from an operator's cellular network onto a wireless local area network (WLAN) that is run by the same operator. Since the WLAN operates on license exempt spectrum, such offloading helps relieve congestion on the licensed cellular spectrum. Cellular bands have become increasingly congested at least in part to the ease with which widely adopted smartphones enable users to utilize data-intensive mobile applications such as email, social networking and Internet browsing.

[0003] Current offloading solutions such as seamless and non-seamless mobility from Third Generation Partnership Project (3 GPP) networks to WLANs tend to be supported only at the core network level. Universal Terrestrial Radio Access (UTRA) and evolved UTRA (E-UTRA, sometimes referred to as Long Term Evolution LTE) are examples of 3 GPP networks. A new study item has been approved in 3 GPP to further enhance offloading efficiency and network utilization, and also to provide more operator control and reduced operating expenses; see document RP-121780 by Intel entitled "WLAN/3GPP Radio Interworking" [3 GPP TSG-RAN Meeting #58; Barcelona, Spain; 4-7 December 2012]. Its stated objectives are to evaluate LTE- WLAN and UTRA- WLAN interworking procedures, including the requirements for radio access network (RAN) level interworking, while improving seamless and non-seamless mobility. [0004] The most recent agreements on this point are in the Chairman's Notes for RAN2-81bis [3 GPP TSG RAN WG2 #8 Ibis; Chicago, USA; 15-19 April 2013] which states: "Solutions should provide improved bi-directional load balancing between WLAN and 3GPP radio access networks in order to provide improved system capacity." There are various 'use-cases' or deployment scenarios, and the Chairman's Notes for use case B state that the "UE is within UTRAN/E-UTRAN and WLAN coverage, is using WLAN and goes out of WLAN AP coverage" and for use case C that the "UE is within the coverage area of both, UE using WLAN, all or a subset of the UE's traffic should be routed via UTRAN/E-UTRAN instead". "AP" refers to the WLAN access point.

[0005] Three other documents are relevant to this traffic offloading issue. Document R2- 130361 by Acer Inc. entitled "Requirements for 3 GPP & WLAN interworking" [3GPP TSG-RAN WG2 #81; St. Julian's, Malta; January 28 to February 1, 2013] notes that "If radio link problems happen in the WLAN, UE is supposed to establish RRC connection back to resume uplink or downlink transmission. In that case, if the UE can fast reconnect to 3 GPP networks, the radio link failure will not be noticed by users, which enhances user experience." "RRC" refers to radio resource control. Document R2- 130321 by Kyocera entitled "3GPP/WLAN interworking scenarios to consider" [3 GPP TSG-RAN WG2 #81 ; St. Julian's, Malta; January 28 to February 1 , 2013] states that: "If the UE were to activate a new service that is not suitable for WLAN, RAN2 should consider procedures necessary for outbound mobility from WLAN to the 3 GPP system.". And document R2-130964 by CATT entitled "Potential solutions for 3GPP/WLAN Network Selection" proposes that a UE in IDLE mode can perform RACH to become CONNECTED and then establish traffic according to conventional RACH practices. "RACH" refers to random access channel. These documents point out the problem but are not seen to offer a viable solution. For this latter document the inventors consider that RACH collision probability and retransmission probability would likely be quite high in an overloaded LTE network where traffic offloading is most effective, meaning it can often take an unacceptably long time for the UE to establish a connection with the LTE network.

[0006] What is needed in the art is a way to switch the UE in the IDLE or CONNECTED state quickly from the WLAN onto which it was offloaded back to the LTE network. Quickness of this switching is required to avoid degrading the quality of the user's experience (QoE).

SUMMARY:

[0007] In a first exemplary aspect of the invention there is a method for operating a user equipment (UE). In this aspect the method comprises: while the user equipment (UE) is attached to a wireless wide area network and operating on a wireless local area network for offloading traffic from the wireless wide area network, initiating at the UE a switch back to the wireless wide area network from the wireless local area network; and indicating to the wireless wide area network via wireless signaling during a connection establishment or connection reestablishment or connection reconfiguration procedure that the UE is switching back from the wireless local area network to the wireless wide area network.

[0008] In a second exemplary aspect of the invention there is an apparatus for operating a user equipment (UE). The apparatus comprises a processing system which itself comprises at least one processor, and at least one memory including computer program code. The processing system is configured to cause the apparatus at least to: initiate at the user equipment (UE) a switch back to a wireless wide area network from a wireless local area network while the UE is attached to the wireless wide area network and operating on the wireless local area network for offloading traffic from the wireless wide area network; and indicate to the wireless wide area network via wireless signaling during a connection establishment or connection reestablishment or connection reconfiguration procedure that the UE is switching back from the wireless local area network to the wireless wide area network.

[0009] In a third exemplary aspect of the invention there is a computer readable memory tangibly storing a set of computer instructions for operating a user equipment. In this aspect the set of computer instructions comprises: code for initiating at the user equipment (UE) a switch back to a wireless wide area network from a wireless local area network while the UE is attached to the wireless wide area network and operating on the wireless local area network for offloading traffic from the wireless wide area network; and code for indicating to the wireless wide area network via wireless signaling during a connection establishment or connection reestablishment or connection reconfiguration procedure that the UE is switching back from the wireless local area network to the wireless wide area network.

[0010] In a fourth exemplary aspect of the invention there is a an apparatus for operating a user equipment, the apparatus comprising: means for initiating at the user equipment (UE) a switch back to a wireless wide area network from a wireless local area network while the UE is attached to the wireless wide area network and operating on the wireless local area network for offloading traffic from the wireless wide area network; and means for indicating to the wireless wide area network via wireless signaling during a connection establishment or connection reestablishment or connection reconfiguration procedure that the UE is switching back from the wireless local area network to the wireless wide area network. In one particular embodiment the means for initiating comprises a processor and a computer readable memory storing a set of computer instructions; and the means for indicating comprises a radio transmitter and an antenna. [001 1 ] These and other aspects are detailed below with more particularity.

BRIEF DESCRIPTION OF THE DRAWINGS:

[0012] Figure 1 is a prior art signaling diagram illustrating a conventional cellular network access using a random access channel ( ACH).

[0013] Figure 2 is a logic flow diagram that illustrates the operation of a method, a result of execution of by apparatus, and execution of computer instructions comprising code embodied on a computer readable memory, in accordance with the embodiments of this invention that are described herein.

[0014] Figure 3 is a table showing a RRC Connection Release message providing the UE 20 with a PRACH sequence reserved for UE switch back purposes according to an exemplary embodiment of these teachings.

[0015] Figure 4 is a table showing a C Connection Request message having such an establishment cause meaning for UE switch back purposes according to an exemplary embodiment of these teachings.

[0016] Figure 5 is a simplified block diagram of a UE in communication with a WLAN access point (AP) and establishing a connection with a cellular access node (eNB) operating under a higher network entity illustrating exemplary electronic devices suitable for use in practicing the exemplary embodiments of this invention.

DETAILED DESCRIPTION:

[0017] The examples detailed herein are in the context of a UE operating in a radio network utilizing the E-UTRAN or LTE radio access technology (including LTE- Advanced), but this is only one example in order to provide a practical context for describing the inventive concepts detailed herein. These teachings may be utilized with other types of wireless wide area radio access technologies, such as for example Universal Terrestrial Access Radio Access (UTRA), High Speed Packet Access (HSPA), Wideband Code Division Multiple Access (WCDMA), Global System for Mobile Communications (GSM), and the like.

[0018] Similarly, while the offload network in these examples is a WLAN using IEEE 802.XX radio access technology, this also is a non-limiting embodiment and these teachings may be deployed when the UE is switching back from any other type of radio access technology in use on the wireless local area networks for offloading traffic from the wireless wide area networks. For example, LTE or other cellular radio access technologies may be deployed as a local area network. The specific names of messages, channels, operating states and various network entities in the examples below follow the nomenclature for LTE and WLAN, and these names also are not limiting to the broader teachings presented below but are for clarity of explanation.

[0019] In general the maximum range of an IEEE 802.xx WLAN is about 150 feet or 50 meters, which is due to transmit power restrictions imposed on use of the license exempt spectrum in which WLANs operate. Cellular radio networks such as LTE and the like operate in licensed radio spectrum and so are not nearly so constrained in their transmit power and practical range. In the description below 'wireless wide area network' refers to a network having a reliable wireless range from a single transmission point greater than about 1000 feet or 300 meters, and the term wireless local area network refers to a network having a reliable wireless range from a single transmission point no greater than about 300 feet or 100 meters. [0020] Consider the scenario of a UE having been offloaded from a LTE cellular network to a WLAN. In one case the UE maintains its connection with the LTE network and only some of its traffic is offloaded to the WLAN. An example of this is if he UE keeps its voice traffic on the LTE network and only is non-voice data traffic is offloaded to the WLAN, so the partially offloaded UE will still have synchronization with the LTE network as well as a temporary network identifier and channelization codes. The more concerning potential for delay arises when the UE no longer has a connection with the LTE network while offloaded to the WLAN. But since in this case the UE was offloaded from the LTE network the UE will generally still be attached to the LTE network, even if not in a connected state (though attached covers both the connected state and an idle state with the LTE network). The LTE network may save the UE's context for some prescribed period of time after being offloaded to the WLAN in case the UE does need to switch back. Typically the UE would remain attached to the LTE network but in an idle or other type of non-connected state. In both partial and full offload cases the UE remains attached to the LTE network while it is offloaded to the WLAN.

[0021 ] Figure 1 is a prior art signaling diagram of a conventional random access channel (RACH) procedure for a UE 20 to get connected to a cellular network, represented in Figure 1 as an eNodeB or eNB 22. There are conventionally two types of RACH procedures, contention based and non-contention based. For non-contention based Figure 1 would include a RACH message 0 prior to RACH message 1 in which the eNB 22 provides to the UE 20 a preamble which the eNB 22 will recognize as being from that particular UE 20. [0022] The conventional contention based RACH procedure begins with RACH message 1 in which the UE 20 sends a random access preamble uplink on the RACH itself. For contention based RACH procedures the UE 20 selects this preamble randomly and uses a random access radio network temporary identifier (RA-RNTI) to inform the eNB 22 how large it's layer 2 or layer 3 (L2/L3) message is to be. The eNB 22 responds with a random access response known as RACH message 2 directed to that RA-RNTI, and RACH message 2 gives the UE 20 the network timing, assigns to the UE a temporary cell radio network temporary identifier (temp C-RNTI) to use for the remainder of the RACH connection process, and allocates uplink resources for the UE 20 to send its L2/L3 message.

[0023] On those allocated uplink resources the UE 20, using the temp C-RNTI, responds with RACH message 3, which is a RRC Connection Request and is the UE's L2/L3 message. RACH message 4 is downlink where the eNB 22 sends a RRC Connection Setup message to give the UE 20 its connection and its (regular) C-RNTI. If there is a conflict from two UE's choosing the same RA-RNTI at the same time and receiving the same temp C-RNTI earlier in the process, the contention is resolved with RACH message 4.

[0024] These conventional RACH procedures are too time consuming for the UE switch back from WLAN scenario since the UE 20 having a traffic flow needs to switch away from the WLAN due to deteriorating channel conditions or the like. For contention based RACH the UE must listen for a period of time to ensure the RACH is clear before it can transmit its preamble, and if there is a collision with another UE in sending the preamble the UE must add another back off factor and listen again before re-attempting RACH message 1. At this point in the conventional RACH process the eNB 22 has no way to prioritize one UE 20 over another for setting up connections. Embodiments of these teachings that utilize an enhanced RACH procedure as described below give the eNB 22 that knowledge so it can prioritize the switch-back UE in view of the eNB's other demands. As will be seen below other embodiments for UE switch back do not use the RACH procedure but rather use other dedicated signaling to indicate to network about the switch-back purpose to facilitate the switch back, for example in connection reestablishment or connection reconfiguration signaling.

[0025] Figure 2 presents a summary of certain of these embodiments from the perspective of the UE 20, and may be considered to represent a method for operating a user equipment (UE) such as for example a UE offloaded from a LTE network to a WLAN and now seeking to switch back to the WLAN. At block 202, while the UE 20 is attached to a wireless wide area network and operating on a wireless local area network for offloading traffic from the wireless wide area network, the UE initiates a switch back to the wireless wide area network from the wireless local area network. Note that in Figure 2 the UE is not switched back by either network but it is the UE 20 that initiates the switchback. As noted above this may be because the UE 20 sees deteriorating channel conditions on the wireless local area network (WLAN), from moving out of range of the WLAN or for other reasons. [0026] Block 204 tells that the UE indicates to the wireless wide area network, via wireless signaling during a connection establishment or connection reestablishment or connection reconfiguration procedure, that the UE is switching back from the wireless local area network to the wireless wide area network. This indication, whatever form it takes, gives the eNB 22 knowledge so it can prioritize getting a connection to this switching back UE 20 over other UEs that may be seeking a connection for purposes that may be less time critical.

[0027] As noted above, certain of these embodiments use an enhanced ACH procedure to inform the network of the switch-back purpose, and block 206 of Figure 2 specifies that the connection establishment procedure stated in block 204 is a random access procedure, and the wireless signaling indicating that the UE is switching back comprises a random access sequence (sometimes referred to as a PRACH sequence) that is reserved for UE switch back purposes. [0028] Block 208 gives two representative embodiments of how such a PRACH sequence can be reserved for UE switch back purposes. In one embodiment the reserved sequence could be pre-defined such as in a wireless standard as being reserved for UE switch back purposes. In this case there is no need to signal the PRACH sequence to the UE 20; both the UE 20 and the eNB 22 will always recognize the reserved PRACH sequence or sequences (if more than one is reserved for this purpose in the published wireless standard) since it will already be stored in their respective local computer readable memories. In another embodiment of how the PRACH sequence(s) can be reserved the eNB 22 dynamically indicates the reserved sequence to the UE 20 when releasing the LTE connection when the UE is offloaded to the wireless local area network (WLAN). For example, the eNB 22 can signal this reserved sequence when commanding the UE to switch to the WLAN, for example in an RRC Connection Release message or in a switching command in the RRC Connection Reconfiguration message which at least indicates partial traffic or all traffic to be switched to the WLAN (or at least partial or full/all bearers or partial or full/all services to be switched to the WLAN). In either case, if the UE 20 uses the reserved sequence in its RACH message 1 , then the eNB 22 will know the UE 20 wants to switch back from WLAN to LTE. Figure 3 is a table showing a RRC Connection Release message providing the UE 20 with a PRACH sequence reserved for switch back purposes shown in bold at 302. For these embodiments the RACH procedure can be non-contention based.

[0029] Block 210 gives another implementation for the reserved PRACH sequence, in which there is a random access preamble group that is reserved for UE switch back purposes, for example Preamble Group C or a subset of some other reserved preamble group. This also may be published in a wireless standard or it may be indicated by the eNB 22 in a master information block (MIB) or other system information block (SIB) which the UE receives and decodes when first connecting to the eNB 22 (before it was offloaded to the WLAN). Or the UE can learn the preamble group reserved for switch back purposed from UE specific signaling from the cellular network. The LTE Release 12 UE knows its purpose to connect to the LTE network is due to switch back and so it knows it is allowed to select a preamble for its RACH message 1 from that reserved group of preambles.

[0030] For example, a new group or subset X_switch of RACH preambles is reserved, for UE switch back purposes. The UE 20 can indicate the switch back to the eNB 22 by selecting a preamble within set S switch; that is, by defining a new preamble group C in SIB2 which is used for Release 12 switch-back UEs. It would then be up to the eNB's implementation to avoid ordering a non-contention based RACH from a legacy UE that uses any preamble within set S switch. This would avoid the possibility of a collision between the switch-back UE and the legacy UE's ordered RACH. It is still possible that two switch-back UEs may select the same preamble within set S_switch if both UEs want to switch back during the same time period, but this is anticipated to be a rare case in practice. In an embodiment even this rare possibility can be avoided or further diminished by having the UEs select a preamble from within the group S switch according to a function that takes as input the UE identifier (UE ID).

[0031 ] The embodiment of block 212 still has the indication that the UE is switching back within an enhanced RACH procedure, but in this case the connection establishment procedure stated at block 204 is a contention based random access procedure and the wireless signaling stated at block 204 indicating that the UE is switching back comprises a Radio Resource Control Connection Request message having an Establishment Cause value that indicates UE switch back. The RRC Connection Request message occurs later in the RACH process (RACH message 3) than the above embodiments but still the eNB 22 can know at that time that this UE is switching back and can expedite the connection setup process after RACH message 3. In this case, if the UE 20 triggers switch back using contention based RACH, it could indicate its purpose and the switch-back traffic in RACH message 3, by signaling in its RRC Connection Request message a new Establishment Cause value having the meaning " ' switch ackFromWLAN'^'' or similar. Figure 4 is a table showing a RRC Connection Request message having such an establishment cause meaning in bold at 402.

[0032] The embodiment of block 214 is later still in a RACH process that is enhanced according to these teachings; the wireless signaling indicating that the UE is switching back comprises a Radio Resource Control Connection Setup Complete message which is the UE's response to RACH message 4 confirming that the UE has the connection with the cellular network. In the block 214 embodiment also the RACH procedure is contention based since the UE did not have a pre-assigned PRACH sequence to send in RACH message 1. If the UE 20 triggers switch back using contention based RACH, it could indicate in this embodiment its switch back purpose and also the switch back traffic in the RRC Connection Setup Complete message.

[0033] Not all embodiments of these teachings modify the RACH procedure to inform the wireless wide area network of the UE switch back. In a different embodiment shown at block 216 the wireless signaling of block 204 indicating that the UE is switching back comprises a Radio Resource Connection Reestablishment Request message in a connection reestablishment procedure. Conventionally, connection reestablishment arises from a radio link failure, a handover failure, a failure of mobility from another network, an integrity check failure (indicated from lower layers), or an RRC connection reconfiguration failure.

[0034] Another embodiment that does not utilize the RACH procedure is for the UE 20 to send newly defined Switch Request signaling to the eNB 22 with the UE's switch-back traffic indication. For example, this switch request signaling could be a newly defined LI signaling message, or a newly defined medium access control (MAC) control element (CE), or radio resource control (RRC) signaling. One example in which this switch request signaling might be useful is where the UE is running voice traffic on the LTE network and internet (or other non-voice data) traffic on the WLAN. As the UE moves out of the WLAN coverage area it may want to switch the internet traffic back to the LTE network. In this case the UE is already in a connected mode with the LTE network via the voice traffic bearer, and so the UE may use a connection reconfiguration procedure to obtain a second bearer for the non-voice data. [0035] In a still further embodiment there is established according to these teachings a new RACH trigger for contention based RACH; when the UE triggers its RACH procedure from this new trigger it is to switch back to the cellular network from the WLAN. For example, such a trigger can be signal strength from the WLAN access point (AP) fading below a threshold minimum and no other suitable APs are in range for the UE 20, or high network congestion in the WLAN. In these cases the RACH procedure that is triggered by this new RACH trigger can be any of the enhanced RACH procedures which are detailed above as informing the eNB of the switch back purpose. [0036] The above embodiments provide the technical effect of enabling fast and reliable switches from WLAN to LTE. Another technical effect is that the above embodiments are backward compatible and so there is no conflict between legacy UEs and UEs that adopt these teachings. Embodiments of these teachings are also simple to implement because they would require only slight change to current specifications for UE and eNB operation in the cellular network.

[0037] The process represented at Figure 2 may be executed by the UE or by one or more components thereof. As non-limiting examples such components may include a processor and a memory storing executable software code, or a universal system identity module (USIM), or a modem, or a USB dongle, or a chipset, or an antenna module, or a radiofrequency RF module (RF front end), or any combination of these. [0038] The logic diagram of Figure 2 may be considered to illustrate the operation of a method, and a result of execution of a computer program stored in a computer readable memory, and a specific manner in which components of an electronic device are configured to cause that electronic device to operate, whether such an electronic device is the UE or some other portable electronic device or component thereof. Figure 2 also implies the mirror processes for the eNB in reading and recognizing the switch back indication. The various blocks shown in Figure 2 may also be considered as a plurality of coupled logic circuit elements constructed to carry out the associated function(s), or specific result of strings of computer program code or instructions stored in a memory. [0039] Such blocks and the functions they represent are non-limiting examples, and may be practiced in various components such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention. [0040] Such circuit/circuitry embodiments include any of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) combinations of circuits and software (and/or firmware), such as: (i) a combination of processor(s) or (ii) portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a user equipment/UE or a radio network access node, to perform the various functions summarized (or implied for the cellular network) at Figure 2 and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. This definition of 'circuitry' applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" also covers, for example, a baseband integrated circuit or applications processor integrated circuit for a user equipment UE or a similar integrated circuit in a radio network that communicates wirelessly with one another.

[0041 ] Reference is now made to Figure 5 for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing the exemplary embodiments of this invention. In Figure 5 a first or cellular radio network access node 22 is adapted for communication over a wireless link 21 A with an apparatus, such as a mobile terminal or UE 20. The access node 22 may be any access node such as a node-B or an eNB (including frequency selective repeaters and remote radio heads) of any wireless network, such as E-UTRAN/LTE/LTE -Advanced, HSPA, WCDMA, GSM, GERAN, UTRAN, and the like. The operator network of which the access node 22 is a part may also include a network control element such as a radio network controller RNC in the case of a UTRAN and WCDMA network, or a mobility management entity MME for the case of LTE/LTE -Advanced networks in which case the MME may also serve as the serving gateway S-GW. This higher network entity 26 generally provides connectivity with the core cellular network and with further networks (e.g., a publicly switched telephone network PSTN and/or a data communications network/Internet). [0042] A second network operating in license exempt spectrum (such as TV whitespaces or the industrial/scientific/medical band) is represented by an access point AP 24 which is adapted for communication over a wireless link 2 IB with the UE 20. The access point 24 is the entity to which the UE 20 was offloaded from the cellular network and the second network is the one from which the UE 20 is seeking to switch back according to exemplary deployments in which these teachings may be deployed. The access point 24 includes processing means such as at least one data processor (DP) 24A, storing means such as at least one computer-readable memory (MEM) 24B storing at least one computer program (PROG) 24C, and communication means such as a transmitter TX 24D and a receiver RX 24E for bidirectional wireless communications with the UE 20 via one or more antennas 24F.

[0043] The UE 20 includes processing means such as at least one data processor (DP) 20A, storing means such as at least one computer-readable memory (MEM) 20B storing at least one computer program (PROG) 20C, and communication means such as a transmitter TX 20D and a receiver RX 20E for bidirectional wireless communications with the access node 22 using the operative radio access technology. All of the relevant wireless communications are facilitated via one or more antennas 20F. Also stored in the MEM 20B at reference number 20G are the computer code or algorithms for the UE to send the UE switch back indication to the cellular network according to exemplary embodiments above.

[0044] The cellular access node 22 also includes processing means such as at least one data processor (DP) 22A, storing means such as at least one computer-readable memory (MEM) 22B storing at least one computer program (PROG) 22C, and communication means such as a transmitter TX 22D and a receiver RX 22E for bidirectional wireless communications with the UE 20 via one or more antennas 22F. The access node 22 stores at block 22G in certain embodiments its own computer software code or algorithms to read and recognize the UE switch back indication that it receives from this UE 20 and from others according to the teachings above. In some radio technologies the cellular access node 22 will have a direct data/control link 23 with other adjacent cellular access nodes. [0045] Also at Figure 5 is shown a higher network entity 26 above the radio access node 22. In UTRAN this higher network entity 26 may be a radio network controller RNC, whereas in LTE/LTE-Advanced this entity 26 may be a MME and/or a S-GW as noted above. However implemented, the higher network entity 26 includes processing means such as at least one data processor (DP) 26A, storing means such as at least one computer-readable memory (MEM) 26B storing at least one computer program (PROG) 26C, and communication means such as a modem 26F for bidirectional communications with the access node 22 and with other access nodes under its control or coordination over the data and control link 27.

[0046] While not particularly illustrated for the UE 20 or the cellular access node 22 or the AP 24, those devices are also assumed to include as part of their wireless communicating means a modem and/or a chipset and/or an antenna chip which may or may not be inbuilt onto a radiofrequency (RF) front end module within those devices 20, 22, 24 and which at least for the UE 20 and the cellular access node 22 also operates according to the teachings set forth above.

[0047] At least one of the PROGs 20C in the UE 20 is assumed to include a set of program instructions that, when executed by the associated DP 20A, enable the device to operate in accordance with the exemplary embodiments of this invention, as detailed above and particularly summarized at Figure 2. The cellular access node 22 also has software stored in its MEM 22B to implement certain aspects of these teachings. In these regards the exemplary embodiments of this invention may be implemented at least in part by computer software stored on the MEM 20B, 22B which is executable by the DP 20A of the UE 20 and/or by the DP 22A of the cellular access node 22; or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware) in any one or more of these devices 20, 22. In this manner the respective DP with the MEM and stored PROG may be considered a data processing system. Electronic devices implementing these aspects of the invention need not be the entire devices as depicted at Figure 5 or may be one or more components of same such as the above described tangibly stored software, hardware, firmware and DP, or a system on a chip SOC or an application specific integrated circuit ASIC or a digital signal processor DSP or a modem or an antenna module or a RF front end module as noted above.

[0048] In general, the various embodiments of the UE 20 can include, but are not limited to personal portable digital devices having wireless communication capabilities, including but not limited to cellular and other mobile phones, navigation devices, laptop/palmtop/tablet computers, digital cameras and music devices, Internet appliances, USB dongles and data cards, machine-to-machine communication devices, and the like. [0049] Various embodiments of the computer readable MEMs 20B, 22B, 24B, 26B include any data storage technology type which is suitable to the local technical environment, including but not limited to semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, removable memory, disc memory, flash memory, DRAM, SRAM, EEPROM and the like. Various embodiments of the DPs 20A, 22A, 24A, 26A include but are not limited to general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and multi-core processors.

[0050] Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description. While the exemplary embodiments have been described above in the context of the LTE/LTE -Advanced systems, as noted above the exemplary embodiments of this invention are not limited for use with only these particular types of wireless radio access technology networks.

[0051 ] Further, some of the various features of the above non-limiting embodiments may be used to advantage without the corresponding use of other described features. The foregoing description should therefore be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.

Claims

WHAT IS CLAIMED IS:

1. A method for operating a user equipment, comprising:

while the user equipment (UE) is attached to a wireless wide area network and operating on a wireless local area network for offloading traffic from the wireless wide area network, initiating at the UE a switch back to the wireless wide area network from the wireless local area network; and

indicating to the wireless wide area network via wireless signaling during a connection establishment or connection reestablishment or connection reconfiguration procedure that the UE is switching back from the wireless local area network to the wireless wide area network.

2. The method according to claim 1, wherein the connection establishment procedure is a random access procedure and the wireless signaling indicating that the UE is switching back comprises a random access sequence reserved for UE switch back purposes.

3. The method according to claim 2, wherein the random access sequence is: pre-defined in a wireless standard as being reserved for UE switch back purposes; or

indicated to the UE in signaling from the wireless wide area network as being reserved for UE switch back purposes when the UE was offloaded from the wireless wide area network to the wireless local area network.

4. The method according to claim 3, wherein the random access sequence is indicated to the UE in a Radio Resource Control Connection Release message.

5. The method according to claim 3, wherein the random access sequence is indicated to the UE in a Radio Resource Control Connection Reconfiguration message.

6. The method according to claim 5, wherein the random access sequence is indicated to the UE in a switching command in the Radio Resource Control Connection Reconfiguration message, wherein the switching command indicates at least partial traffic/bearers/services or all traffic/bearers/services to be switched to the wireless local area network.

7. The method according to claim 2, wherein the random access sequence is: selected from a random access preamble group that is reserved for UE switch back purposes.

8. The method according to any of claims 2-7, wherein the random access procedure is triggered at the UE by fading signal strength or network congestion from the local area network.

9. The method according to claim 1, wherein the connection establishment procedure is a contention based random access procedure and the wireless signaling indicating that the UE is switching back comprises a Radio Resource Control

Connection Request message having an establishment cause value that indicates UE switch back.

10. The method according to claim 1, wherein the connection establishment procedure is a contention based random access procedure and the wireless signaling indicating that the UE is switching back comprises a Radio Resource Control

Connection Setup Complete message.

11. The method according to claim 1 , wherein the wireless signaling indicating that the UE is switching back comprises a Radio Resource Control Connection

Reestablishment Request message in a connection reestablishment procedure.

12. The method according to claim 1 , wherein the wireless signaling indicating that the UE is switching back comprises switch request signaling having a switch back indication, where the switch back request signaling is sent while the UE is in a Radio Resource Control CONNECTED mode.

13. The method according to claim 1 , wherein the wireless signaling indicating that the UE is switching back comprises layer 1 (LI) signaling, or medium access control (MAC) signaling, or radio resource control signaling.

14. The method according to any of claims 1-13, wherein the wireless wide area network is an evolved Universal Terrestrial Radio Access Network (E-UTRAN) or Universal Terrestrial Radio Access Network (UTRAN).

15. An apparatus for operating a user equipment, the apparatus comprising a processing system, and the processing system comprising at least one processor and at least one memory including computer program code;

wherein the processing system is configured to cause the apparatus at least to:

initiate at the user equipment (UE) a switch back to the wireless wide area network from the wireless local area network while the UE is attached to a wireless wide area network and operating on a wireless local area network for offloading traffic from the wireless wide area network; and

indicate to the wireless wide area network via wireless signaling during a connection establishment or connection reestablishment or connection reconfiguration procedure that the UE is switching back from the wireless local area network to the wireless wide area network.

16. The apparatus according to claim 15, wherein the connection establishment procedure is a random access procedure and the wireless signaling indicating that the UE is switching back comprises a random access sequence reserved for UE switch back purposes.

17. The apparatus according to claim 16, wherein the random access sequence is: pre-defined in a wireless standard as being reserved for UE switch back purposes; or

18. The apparatus according to claim 17, wherein the random access sequence is indicated to the UE in a Radio Resource Control Connection Release message.

19. The apparatus according to claim 17, wherein the random access sequence is indicated to the UE in a Radio Resource Control Connection Reconfiguration message.

20. The apparatus according to claim 19, wherein the random access sequence is indicated to the UE in a switching command in the Radio Resource Control Connection Reconfiguration message, wherein the switching command indicates at least partial traffic/bearers/services or all traffic/bearers/services to be switched to the wireless local area network.

21. The apparatus according to claim 16, wherein the random access sequence is: selected from a random access preamble group that is reserved for UE switch back purposes.

22. The apparatus according to any of claims 16-21, wherein the random access procedure is triggered at the UE by fading signal strength or network congestion or network congestion from the local area network.

23. The apparatus according to claim 15, wherein the connection establishment procedure is a contention based random access procedure and the wireless signaling indicating that the UE is switching back comprises a Radio Resource Control

24. The apparatus according to claim 15, wherein the connection establishment procedure is a contention based random access procedure and the wireless signaling indicating that the UE is switching back comprises a Radio Resource Control

Connection Setup Complete message.

25. The apparatus according to claim 15, wherein the wireless signaling indicating that the UE is switching back comprises a Radio Resource Connection Reestablishment Request message in a connection reestablishment procedure.

26. The apparatus according to claim 15, wherein the wireless signaling indicating that the UE is switching back comprises switch request signaling having a switch back indication, where the switch back request signaling is sent while the UE is in a Radio Resource Control CONNECTED mode.

27. The apparatus according to claim 15, wherein the wireless signaling indicating that the UE is switching back comprises layer 1 (LI) signaling, or medium access control (MAC) signaling, or radio resource control signaling.

28. The apparatus according to any of claims 15-27, wherein the wireless wide area network is an evolved Universal Terrestrial Radio Access Network (E-UTRAN) or Universal Terrestrial Radio Access Network (UTRAN).

29. A computer readable memory tangibly storing a set of computer instructions for operating a user equipment, the set of computer instructions comprising:

code for initiating at the user equipment (UE) a switch back to a wireless wide area network from a wireless local area network while the UE is attached to the wireless wide area network and operating on the wireless local area network for offloading traffic from the wireless wide area network; and

code for indicating to the wireless wide area network via wireless signaling during a connection establishment or connection reestablishment or connection reconfiguration procedure that the UE is switching back from the wireless local area network to the wireless wide area network.

30. The computer readable memory according to claim 29, wherein the connection establishment procedure is a random access procedure and the wireless signaling indicating that the UE is switching back comprises a random access sequence reserved for UE switch back purposes.

31. The computer readable memory according to claim 30, wherein the random access sequence is:

pre-defined in a wireless standard as being reserved for UE switch back purposes; or

32. The computer readable memory according to claim 31 , wherein the random access sequence is indicated to the UE in a Radio Resource Control Connection Release message.

33. The computer readable memory according to claim 31 , wherein the random access sequence is indicated to the UE in a Radio Resource Control Connection Reconfiguration message.

34. The computer readable memory according to claim 33, wherein the random access sequence is indicated to the UE in a switching command in the Radio Resource Control Connection Reconfiguration message, wherein the switching command indicates at least partial traffic/bearers/services or all traffic/bearers/services to be switched to the wireless local area network.

35. The computer readable memory according to claim 30, wherein the random access sequence is:

selected from a random access preamble group that is reserved for UE switch back purposes.

36. The computer readable memory according to any of claims 30-35, wherein the random access procedure is triggered at the UE by fading signal strength or network congestion from the local area network.

37. The computer readable memory according to claim 29, wherein the connection establishment procedure is a contention based random access procedure and the wireless signaling indicating that the UE is switching back comprises a Radio Resource Control Connection Request message having an establishment cause value that indicates UE switch back.

38. The computer readable memory according to claim 29, wherein the connection establishment procedure is a contention based random access procedure and the wireless signaling indicating that the UE is switching back comprises a Radio Resource Control Connection Setup Complete message.

39. The computer readable memory according to claim 29, wherein the wireless signaling indicating that the UE is switching back comprises a Radio Resource Connection Reestablishment Request message in a connection reestablishment procedure.

40. The computer readable memory according to claim 29, wherein the wireless signaling indicating that the UE is switching back comprises switch request signaling having a switch back indication, where the switch back request signaling is sent while the UE is in a Radio Resource Control CONNECTED mode.

41. The computer readable memory according to claim 29, wherein the wireless signaling indicating that the UE is switching back comprises layer 1 (LI) signaling, or medium access control (MAC) signaling, or radio resource control signaling.

42. The computer readable memory according to any of claims 29-41, wherein the wireless wide area network is an evolved Universal Terrestrial Radio Access Network (E-UTRAN) or Universal Terrestrial Radio Access Network (UTRAN).

43. An apparatus for operating a user equipment, the apparatus comprising

means for initiating at the user equipment (UE) a switch back to a wireless wide area network from a wireless local area network while the UE is attached to the wireless wide area network and operating on the wireless local area network using license exempt spectrum for offloading traffic from the wireless wide area network; and

means for indicating to the wireless wide area network via wireless signaling during a connection establishment or connection reestablishment or connection reconfiguration procedure that the UE is switching back from the wireless local area network to the wireless wide area network.

44. The apparatus according to claim 43, wherein the means for initiating comprises a processor and a computer readable memory storing a set of computer instructions; and the means for indicating comprises a radio transmitter and an antenna.