WO2014140408A1

WO2014140408A1 - Power saving for a mobile station during connection setup

Info

Publication number: WO2014140408A1
Application number: PCT/FI2013/050263
Authority: WO
Inventors: Jarkko Lauri Sakari Kneckt; Teemu Savolainen; Markus ISOMÄKI
Original assignee: Nokia Corporation
Priority date: 2013-03-11
Filing date: 2013-03-11
Publication date: 2014-09-18

Abstract

This document discloses a power saving solution for use by a first wireless apparatus during connection establishment. The first wireless apparatus may determine a delay for a connection establishment phase of a connection between the first wireless apparatus and a second wireless apparatus. The first wireless apparatus may cause transmission of a request message to the second wireless apparatus during a connection establishment with said second wireless apparatus. The apparatus may suspend scanning for a response message from the second wireless apparatus during at least a portion of the determined delay in the connection establishment for carrying out power saving.

Description

POWER SAVING FOR A MOBILE STATION DURING CONNECTION SETUP

Field

The invention relates to the field of wireless networks and, particularly, to operation during a connection establishment procedure in a wireless apparatus. Background

During a link establishment procedure where a wireless apparatus connects to another wireless apparatus, control messages may be exchanged between the wireless apparatuses. Typically, delays caused by radio wave propagation and processing are present in the exchange of the control messages. Brief description

The invention is defined by the independent claims

Embodiments of the invention are defined in the dependent claims.

List of drawings

Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which

Figure 1 illustrates a wireless communication scenario to which embodiments of the invention may be applied;

Figure 2 is a flow diagram illustrating a process for operating a wireless apparatus during delays associated with exchange of messages during a connection establishment procedure according to an embodiment of the invention;

Figures 3A and 3B illustrate operation during delays associated with request-response message exchanges between a terminal device and an access node according to an embodiment of the invention;

Figure 4 illustrates phases of the link establishment procedure to which some embodiments of the invention may be applied;

Figure 5 illustrates utilization of the delays in connection with the link establishment in the terminal device according an embodiment of the invention;

Figure 6 illustrates a signalling diagram of a procedure in which an access node informs the delays to the terminal device dynamically according to an embodiment of the invention;

Figure 7 illustrates a process for acquiring a static database storing the delays according to an embodiment of the invention;

Figure 8 illustrates a process for determining the delays autonomously by the terminal device according to an embodiment of the invention; and Figure 9 is a block diagram illustrating a structure of an apparatus according to an embodiment of the invention.

Description of embodiments

The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words "comprising" and "including" should be understood as not limiting the described embodiments to consist of only those features that have been mentioned and such embodiments may contain also features/structures that have not been specifically mentioned.

A general wireless communication scenario to which embodiments of the invention may be applied is illustrated in Figure 1 . Figure 1 illustrates wireless communication devices comprising access points (AP) 100 and a plurality of terminal devices (STA) 104, 106. The APs 100, 102 may be stationary access points. A general term used in this specification and encompassing both the APs and STAs is a wireless apparatus. The access point may refer to an access point specified in IEEE 802.1 1 specifications or to a base station of another wireless access network. At least one of the terminal devices 106 may have a functionality of an AP as well. Therefore, a common term encompassing both the stationary APs 100, 102 and mobile APs 106 is an access node. An access node 100, 102, 106 may provide or be comprised in a basic service set (BSS) which is a basic building block of an IEEE 802.1 1 wireless local area network (WLAN). Each access node 100, 102, 106 may represent a different BSS. The most common BSS type is an infrastructure BSS that includes a single access node together with all STAs associated with the AP. The access node may provide access to other networks, e.g. the Internet 1 10. In another embodiment, the BSSs may be connected with each other by a distribution system (DS) to form an extended service set (ESS). An independent BSS (IBSS) is formed by an ad hoc network of terminal devices without a stationary controlling access point. While embodiments of the invention are described in the context of the above-described topologies of IEEE 802.1 1 , it should be appreciated that these or other embodiments of the invention may be applicable to networks based on other specifications, e.g. WiMAX (Worldwide Interoperability for Microwave Access), UMTS LTE (Long-term Evolution for Universal Mobile Telecommunication System), mobile ad hoc networks (MANET), mesh networks, and other networks having cognitive radio features, e.g. transmission medium sensing features and adaptive capability to coexist with radio access networks based on different specifications and/or standards. Some embodiments may be applicable to networks having features under development by other IEEE task groups, e.g. 802.19 task group 1 (TG1 ).

The different access nodes 100, 102, 106 may operate at least partly on different channels, e.g. on different frequency channels. IEEE 802.1 1 η specification specifies a data transmission mode that includes 20 megahertz (MHz) wide primary and secondary channels. The primary channel is used in all data transmissions with clients supporting only the 20 MHz mode and with clients supporting higher bandwidths. A further definition in 802.1 1 η is that the primary and secondary channels are adjacent. The 802.1 1 η specification also defines a mode in which a STA may, in addition to the primary channel, occupy one secondary channel which results in a maximum bandwidth of 40 MHz. IEEE 802.1 1 ac task group extends such an operation model to provide for wider bandwidths by increasing the number of secondary channels from 1 up to 7, thus resulting in bandwidths of 20 MHz, 40 MHz, 80 MHz, and 160 MHz. A 40 MHz transmission band may be formed by two contiguous 20 MHz bands, and an 80 MHz transmission band may be formed by two contiguous 40 MHz bands. However, a 160 MHz band may be formed by two contiguous or non-contiguous 80 MHz bands. Different BSSs may employ different primary channels.

As mentioned above, the transmission band of a BSS contains the primary channel and zero or more secondary channels. The secondary channels may be used to increase data transfer capacity of a transmission opportunity (TXOP). The secondary channels may be called a secondary channel, a tertiary channel, a quaternary channel, etc. However, let us for the sake of simplicity use the secondary channel as the common term to refer also to the tertiary or quaternary channel, etc. The primary channel may be used for channel contention, and a TXOP may be gained after successful channel contention on the primary channel. Some IEEE 802.1 1 networks are based on carrier sense multiple access with collision avoidance (CSMA/CA) for channel access. Some networks may employ enhanced distributed channel access (EDCA) which provides quality-of- service (QoS) enhancements to medium access control (MAC) layer. The QoS enhancements may be realized by providing a plurality of access categories (AC) for prioritizing frame transmissions. The access categories may comprise the following priority levels in the order of increasing priority: background (AC_BK), best effort (AC_BE), video streaming (AC_VI), and voice (AC_VO). A higher priority frame transmission may use a shorter contention window and a shorter arbitration inter-frame spacing (AIFS) that result in higher probability of gaining the TXOP.

As described above, the BSS may be represented by the access node and one or more terminal devices connected to the access node. A terminal device 102 may establish a connection with any one of the access nodes 100, 102, 106 it has detected to provide a wireless connection within the neighbourhood of the terminal device. The connection establishment may include authentication in which an identity of the terminal device is established in the access node. The authentication may comprise exchanging an encryption key used in the BSS. After the authentication, the access node and the terminal device may carry out association in which the terminal device is fully registered in the BSS, e.g. by providing the terminal device with an association identifier (AID). It should be noted that in other systems terms authentication and association are not necessarily used and, therefore, the association of the terminal device to an access node should be understood broadly as establishing a connection between the terminal device and the access node such that the terminal device is in a connected state with respect to the access node and scanning for downlink frame transmissions from the access node and its own buffers for uplink frame transmissions.

IEEE 802.1 1 ai task group is creating principles for fast initial link setup (FILS). One aspect of the principles is to enable faster and more precise AP and network discovery. Some principles relate to passive scanning in which a scanning device, e.g. a STA, passively scans channels for any beacon, management, or advertisement frames. Other principles relate to active scanning in which the scanning device actively transmits a scanning request message, e.g. a Probe Request message or a generic advertisement service (GAS) request, in order to query for present APs or networks. The probe request may also set some conditions that a responding device should fulfil in order to respond to the probe request. In some embodiments, the scanning device may be called a requesting device or a requesting apparatus. Responding devices may transmit scanning response messages, e.g. Probe Response messages, in response to the scanning request message, wherein the scanning response message may contain information on the responding device, its network, and other networks.

Embodiments described herein are applicable to a multipath scenario in which a terminal device 104 operates a plurality of parallel associations to different access nodes 100, 102, 106. The terminal device 104 may utilize the multipath scenario to provide a multipath connection to a network server or, in general, a network device via multiple different access nodes. The multipath connection may be a transport or network level connection between the terminal device 104 and the network device, and it may comprise at least two parallel radio links through different access nodes 100, 102, 106. The use of the parallel radio links may be used in order to improve data throughput. The increase in throughput may be realized with the additional capacity in the radio interface and in the backbone link between each access node and the network device to which the multipath connection is established. As a consequence, different data may be routed through different radio links and backbones between the terminal device and the network device. Such a multipath connection is supported on higher protocol layers, e.g. by a multipath real time protocol, multipath transport control protocol (TCP) and multipath universal datagram protocol (UDP) defined within Internet Engineering Task Force (IETF). IEEE 802.1 1 (WLAN/Wi-Fi) radio is one of the main candidate radios to be used with the multipath protocols. The multipath connection may be employed for an application executed in the terminal device, and the application itself may be unaware of whether or not the connection is the multipath connection. Similarly, if the application transmits and receives data from multiple sources through separate TCP sessions, the terminal may allocate different TCP sessions to different links and hide the complexity by using a protocol similar to the multipath TCP. The parallel associations may, however, be used for other purposes as well.

The WLAN radio may be enabled to associate / establish links with many access nodes. Use of multiple links is advantageous, if the associated access nodes are capable of transmitting traffic efficiently over the air interface but backbone links of the access nodes used to connect the access nodes to the Internet have a low throughput, e.g. an ADSL (asynchronous digital subscriber line) modem. In these cases, operating with multiple APs may increase the total throughput experienced by the terminal device.

Embodiments of the invention relate to a link establishment procedure in which a terminal device negotiates with an access node with respect to initializing a link between the terminal device and a wireless access network comprising the access node. The link establishment comprises exchange of signalling messages and delays caused by radio propagation and processing of the link establishment in the wireless access network, e.g. by the access node or any other network entity managing the link establishment from the side of the wireless access network. Such delays are idle time for the terminal device in terms that the access node may not transmit frames to the terminal device during the delay. Similar delays exist when a message transmitted from the access node to the terminal device is being processed in the terminal device. Figure 2 illustrates a flow diagram of a process for utilizing such idle time associated with a connection establishment phase in a wireless apparatus. The process of Figure 2 may be carried out as a computer process in the wireless apparatus. With respect to the process of Figure 2 and other processes described herein, the process may be launched by a determined event indicated by "Start", and the process may end when it has been completed (indicated by "End"). It should be appreciated that other functions may be performed before and/or after the execution of the process.

Referring to Figure 2, an wireless apparatus determines a delay for a connection establishment phase of a link between the wireless apparatus and another wireless apparatus. In block 204, the wireless apparatus transmits a request message to the other wireless apparatus during a connection establishment with said other wireless apparatus. In block 206, the wireless apparatus suspends scanning for any messages from the other apparatus for the duration of the determined delay in the connection establishment. In block 208, the wireless apparatus acquires a response to the request message.

During the suspension of the scanning, the wireless apparatus may perform other tasks or doze. The other tasks may comprise operating in another connection established by the wireless apparatus. The other connection may have been established with a third wireless apparatus, and the operation in the other connection may comprise-carrying out data frame transmission and/or reception in the other connection.

In an embodiment, the wireless apparatus carrying out the method of

Figure 2 is the terminal device. A starting point of the process of Figure 2 may be that the terminal device has established said other connection and, in some embodiments, a plurality of other links and is scanning for a new wireless access network in order to increase the number of links. The reason for increasing the number of established links may be preparation for a handover, transition, or roaming from one access node or wireless access network to another or to increase the number of links that may be used in data transmissions, e.g. in the multipath data transmission described above.

The connection establishment phase may be understood to comprise a single, continuous time interval during the connection establishment or one or more sub-intervals during the connection establishment, as described below. As a consequence, the terminal device may utilize one or more separated delays within the same connection establishment process to enter the doze mode and/or operate in the other link. The terminal device may utilize a first subset of the delays to enter the doze mode and a second, different subset of the delays to operate in the other link.

With respect to the definition of the doze mode, a terminal device operating in the doze mode may be considered as hibernating. For example, the terminal device in the doze mode may have shut down at least some of its transceiver circuitries. According to another point of view, the terminal device is not able to communicate with the access node in the doze mode. When the terminal device awakes from the doze mode, it powers up its transceiver circuitries and is able to communicate with the access node. The terminal device may employ the doze mode to reduce its functions, to reduce power consumption, and to prolong battery lifetime. When the terminal device with a single transceiver uses a multipath protocol with access nodes having different operating channels, the terminal device may operate on a single channel at a time, when not dozing, so it may be considered to doze or, in other words, operate in the doze mode towards the other access nodes.

In another embodiment, a process similar to that of Figure 2 is carried out by the access node during the connection setup with the terminal device. The access node may determine any delays caused by the processing in the terminal device during the connection setup, and use such delays to doze or operate another link. The connection setup processing delays associated with the terminal device may be reported by a network server, or the access node may obtain the delays from a model of the terminal device a chip set number of the terminal device, or a medium access control (MAC) address of the terminal device communicated to the access node during the connection setup.

If the access node is powered by a battery or operating in a poweroptimized mode, the access node may use the information on the delays to operate in the doze mode when the terminal is processing the connection setup messages transmitted by the access node. Similarly, if the terminal device is creating a connection with the Wi-Fi Direct group owner, or with a mesh node at wireless mesh network, such a device to which the terminal is creating a connection may utilize the delays to operate in the doze mode.

Below, some embodiments of the invention are described in connection with Figures 3 to 8 from the point of view that the terminal device determines the delays associated with the processing in the access node, a group owner of a wireless network, e.g. the Wi-Fi Direct, or a node of a wireless mesh network. However, it should be appreciated that embodiments are equally applicable to reversed situations where the access node, group owner, or the node of the wireless mesh network determines the delays associated with the processing in the terminal device. Reversing the described embodiments on the basis of the description provided below is straightforward to a person skilled in the art, since it requires nothing more than simply switching the roles of the access node and the terminal device and, possibly, routine modifications.

Let us now consider the utilization of the delays associated with the connection establishment with reference to a signalling diagram of Figure 3. Referring to Figure 3, an access node broadcasts a discovery signal in step 300. The discovery signal may be a beacon signal, a pilot signal, a probe response signal, or any other signal the access node broadcasts to announce the presence of a wireless access network of the access node. In block 302, the terminal device receives the discovery signal and detects the access node and the wireless access network of the access node. The terminal device may also determine in block 302 one or more delays associated with connection establishment with the access node or the wireless access network. Embodiments for determining the delay(s) are described below. The terminal device may determine one or more delays associated with the exchange of request-response messages between the terminal device and the access node. Different request-response messages may be associated with different delays, and the terminal device may be provided information on these delays of the different request-response message exchanges.

In an embodiment, the terminal device determines the delay between transmission of a request message from the terminal device and reception of the corresponding response message in the terminal device. The request message may be a probe request, an authentication request, or an association request of an IEEE 802.1 1 network, for example. Figure 3A illustrates this embodiment, wherein the terminal device transmits a request message to the access node in step 304. Upon reception of the request message, the access node processes the request in block 306. Meanwhile, the terminal device dozes or operates the other connection in block 308 during the delay 305 associated with processing in block 306 and possible channel access and/or radio propagation delay(s) associated with the transmission of the request message and reception of a response to the request. Upon processing the request message and having formed the response to the request message, the access node transmits the response to the terminal device in step 310. The terminal device may have returned to scan for transmissions from the access node and, thus, receives the response message and processes the response in block 312. Then, the terminal device may transmit another request message in step 314 and utilizes a delay 315 associated with this request to doze or operate the other link. In this manner, the terminal device may carry out multi- tasking or save battery during the delays 305, 315 associated with the processing in the access node and/or another network element of the wireless access network carrying out the connection establishment.

In another embodiment, the terminal device determines the delay between transmission of a response message from the terminal device and reception of a subsequent request message in the terminal device. In some cellular communication networks, e.g. the LTE, a network element initiates authentication by transmitting a request message to the terminal device. After the terminal device has processed the authentication request and transmitted an associated response, there may be a delay before the next message from a network element of the cellular communication network, and the terminal device may utilize this delay to doze or operate another connection during the establishment of the new link. Figure 3B illustrates this embodiment. In steps 350 and 352, the terminal device discovers the wireless access network, as described above in connection with steps 300, 302. Then, the terminal device may transmit a request message to the access node (step 354), wherein the request message may be, for example, a registration request message to register the terminal device to the wireless access network. During the delay (355) associated with processing the request in block 356 by the access node or another network element, the terminal device dozes or operates the other connection in block 358 and returns to receive the response message in step 360 and process the response in block 362. Now, the network element may transmit a subsequent request message in step 364, e.g. an authentication request sent by a mobility management entity (MME). The terminal device may process the request in block 366 and transmit a response in step 368. During the delay 365 associated with processing the response in block 370 in the network, the terminal device may doze or operate the other connection in block 372. Thereafter, the procedure may continue with the transfer or a subsequent message, e.g. another request message sent from the access node to the terminal device in step 374.

In an embodiment, the access node supports terminal operation in the power-save mode, e.g. service periods as defined in Automatic Power Save Delivery (APSD) of the IEEE 802.1 1 networks may be used in the connection setup. The terminal device may transmit a frame to the access node to initiate a service period. After the initiation, the access node may transmit data traffic, and the access node may indicate termination of the service period in the last frame transmitted to the terminal device. The next data transmission from the access node may require another initiation of the service period from the terminal device. The terminal device may control the initiation of the service period and, thus, define the time instants when it wishes to receive data from the access node. Correspondingly, the access node may control the termination of the service period, i.e. the duration of the service or data transmission period. This operation may be applied to the connection setup such that the terminal device may use the service periods to control the times when the access node may transmit connection setup messages to the terminal device. The terminal device may thus operate in the power-save mode (doze) between the service periods during the connection setup. The terminal device may use the delay information associated with the processing of the messages, as determined in block 202, to decide when it should trigger a service period to receive a subsequent connection setup message. The knowledge of the delay reduces connection setup delays and the number of unnecessary service periods that may occur if the terminal triggers a service period before the access node has prepared the connection setup message for the transmission to the terminal device.

In an embodiment, the terminal device starts the dozing or operating the other connection upon transmitting a message to the access node, if the terminal device determines that there is a certain delay before it receives a subsequent message from the access node. The message may be a request message, response message, or a positive acknowledgment message used by the terminal device to acknowledge correct reception of a message from the access node. In another embodiment, the terminal device starts the dozing or operating the other connection upon receiving a message from the access node, if the terminal device determines that there is a certain delay before it receives a subsequent message from the access node. The received message may be a response message or a positive acknowledgment message from the access node to acknowledge correct reception of a message from the access node.

Let us now consider some phases of the connection establishment when the dozing or multi-tasking may be utilized according to an embodiment of the invention. Figure 4 illustrates a timeline of a scenario where the terminal device has at least one operational connection with a first wireless access network (illustrated by block 400). The terminal device may transmit and/or receive data traffic over the operational connection 400 during the establishment of the new link, as illustrated in Figure 4. With respect to the operational mode, the terminal device may have signaled on layer 3, for example, to use the connection and the terminal device may thus constantly or periodically check for arriving traffic based on the traffic profile.

The terminal device is about to discover and establish a new connection with a second wireless access network, e.g. with a different access node than that operating the operational connection 400. In block 402, the terminal device discovers the second wireless access network on the basis of detection of a discovery signal transmitted by an access node of the second wireless access network. In block 404, the terminal device starts a connection establishment process with the access node of the second wireless access network. The terminal device may have a preconfigured threshold when it should start a new connection setup in order to ensure fluent handover and/or to minimize the power consumption. The threshold may include a received signaling strength indicator (RSSI) threshold with which an RSSI of a signal received from an access node of the currently operational connection 400 is compared. The threshold may be use of a determined modulation and coding set (MCS), e.g. a low-order MCS used in connection with poor channel conditions may trigger the establishment of the new link. Another criterion may be a connection setup time of the new link. When the connection setup time is long, the initiation of the establishment of the connection may be started more easily, e.g. at larger RSSI or higher order MCS. In other words, the threshold(s) for triggering the connection creation may be lowered as the connection setup time increases.

The terminal device may utilize any delays associated with the processing in the access node and/or any other network element of the second wireless access network to operate the operational connection 400 or to doze, as described above. The connection establishment may comprise authentication and association procedure, an internet protocol (IP) address configuration, and/or any other connection establishment procedures. The connection establishment in block 404 may comprise transfer of several messages between the terminal device and the access node, as described below.

After the connection establishment, the terminal device may set the connection to a stand-by or to an operational mode, depending on transmission capacity and reliability requirements. If the currently operational connection 400 cannot provide sufficient transmission capacity and/or reliability, the terminal device may use the new connection as an additional operational connection and transfer data over both links in parallel, e.g. by using the multipath TCP transmission. On the other hand, if the currently operational connection 400 provides a sufficient data transmission capacity and reliability, the terminal device may put the new connection into the stand-by mode, as in the example of Figure 4 (illustrated by block 406). Another criterion for using the stand-by mode may be a battery status of the terminal device. The terminal device may put the connection into the stand-by mode by preventing transmission of frames to the connection and wait that inactivity at the connection will cause the access node to put the connection to the stand-by mode. Alternatively, the terminal device may transmit an explicit frame to the access node to actively set the connection to the stand-by state. The frame may be a disassociation request frame or a disauthentication request frame.

In yet another embodiment, the terminal device may establish two independent connections to different wireless access networks. One connection may be used to establish a first transport level connection to a first network, e.g. an intranet, and the other connection may be used to establish a second transport level connection to another network, e.g. the Internet. In yet another embodiment, a wireless apparatus performing the functions of the terminal device described above may be a router apparatus between two wireless access networks. It may have established a connection with both wireless access networks and forward traffic between the two wireless access networks by forwarding data from one connection to the other.

Let us now consider some stand-by modes. In a discovered mode, the terminal device may have discovered the wireless access network but is not authenticated to the access node. This stand-by mode may be realized with the transmission of the disauthentication request frame after the connection establishment. In an authenticated mode, the terminal device has authenticated with the wireless access network but is not associated with the access node of the wireless access network.

In a new connection mode, the terminal device has associated with the access node and configured IP addresses through the access node but no traffic is transferred between the terminal device and the access node. The connection may be activated with simple association level signaling. The terminal device may be required to transmit a frame periodically to maintain operation in the new connection mode, wherein the frame may be a management, data or control frame. The IP address(es) configured to the terminal device may have a preconfigured lifetime. When the terminal device is not transferring messages with the access node, it may have an effect on the configured IP address(es). In the case of a dynamic host configuration protocol (DHCP) based address allocation schemes, the terminal device may be required to periodically become active and renew address leases or, otherwise, the IP address may cease to be allocated to the terminal device. In the case of IPv6 Stateless Address Autoconfigu ration, the terminal device may be required to periodically wake up to receive router advertisement signals. With respect to an address resolution protocol (ARP), a gateway of the wireless access network may implement a proxy-ARP functionality in order to defend the IP addresses of terminal devices that are not active but still associated. In the case of IPv6, the terminal device may be able to ask the gateway to defend the terminal device's address with internet control message protocol ICMPv6 Address Registration Option (ARO). When the terminal device assumes that its IP address is still valid, e.g. based on these tools and knowledge about valid association with the access node, the terminal device may start using the IP address immediately after changing the new connection from the stand-by mode to an operational mode and, hence, shorten the time it takes for connection to be in the operational mode. The terminal device may, however, perform a check for ensuring that the IP address is still valid.

In a pseudo-operational mode, the terminal device may be associated and with the access node and have the IP address allocation. The terminal device may, however, disabled allocation of any traffic to the new connection on top of an IP layer in a protocol stack, e.g. through transport (TCP) or application level (hypertext transfer protocol, HTTP). Accordingly, all the data traffic may be steered to the operational connection 400, and the terminal device is not expecting to receive any data traffic over the new link. As a consequence, it may minimize connection maintenance and transmit a frame to the connection only to maintain the connection available.

Before the switching the connection to the stand-by mode, the terminal device may test the operation of the link. In the test, the terminal device may authenticate and associate with the access node and test IP traffic transfer with a determined network server, for example. If the test is successful in terms of performance of the connection with the network server, the terminal device may switch the connection to the stand-by mode. If the test fails, the terminal device may terminate the link.

In general, the stand-by mode of the connection may be defined as a state where the terminal device does not transfer any data traffic with the access node and where the connection may be switched to the operational mode with less signaling than in the case where the terminal device should establish the connection from the scratch. In block 408, the terminal device activates the new connection to switch it from the stand-by mode to the operational mode (block 410). The activation in block 408 may comprise exchange of signaling messages between the terminal device and the access node and, optionally, another network element of the second wireless access network. The amount of signaling may depend on the stand-by mode applied, e.g. it may comprise authentication and/or association signaling. The terminal device may utilize any delay associated with the signaling in block 408 to doze or operate the operational connection 400.

Each application may have predefined data delivery and maximum connection activation times. The terminal device may maintain the new connection at a state that enables the connection activation within the maximum activation time. As a consequence, the terminal device may select the appropriate stand-by mode according to the maximum connection activation time of the application using the operational connection 400. An example of the maximum connection activation time is 100 milliseconds.

Figure 5 illustrates a signaling diagram comprises phases of the connection establishment procedure. The terminal device may utilize the delays in connection with any one of the phases to doze or operate the other link, as illustrated in Figure 5. Referring to Figure 5, a network discovery phase may comprise the terminal device transmitting a scanning request message to the access node in step 500. The scanning request message may be a probe request, for example. While the access node processes the scanning request in block 502, the terminal device may utilize the associated delay 505 to doze or operate the other connection in block 504 and to return to scan for a scanning response message after the determined delay. In step 506, the access node transmits the scanning response message to the terminal device, and the terminal device processes the response in block 508. The scanning response message may be a probe response associated with the probe request of step 500.

After the terminal device has discovered the access node and the wireless access network of the access node, the terminal device may transmit an authentication request message to the access node in step 510. The authentication may be carried out by an authentication server which may reside in a different location than the access node. Therefore, the access node may need to relay the authentication request to the authentication server, and the associated delay 515 may be longer than the delay 505 when the access node itself processes the request. While the authentication server and the access node process the authentication request in block 512, the terminal device may utilize the associated delay 515 to doze or operate the other connection in block 514 and to return to scan for an authentication response message after the determined delay. In step 516, the access node transmits the authentication response message to the terminal device, and the terminal device processes the response in block 518.

The authentication may comprise a plurality of separate request- response message exchanges. For example, in 802.1 1 networks the authentication may comprise zero authentication and/or extensible authentication protocol (EAP) authentication. The EAP authentication may comprise transmission of several request-response pairs, all having delays caused by the processing in the access node and/or the authentication server. Some of the requests may be transmitted by the terminal device, while other requests may be transmitted by the access node or the authentication server.

With respect to the association, the terminal device may transmit an association request message to the access node in step 520. The association may be carried out by the access node. While the access node processes the association request in block 522, the terminal device may utilize the associated delay 525 to doze or operate the other connection in block 524 and to return to scan for an association response message after the determined delay. In step 526, the access node transmits the association response message to the terminal device, and the terminal device processes the response in block 528.

After the association, or in connection with the association, the terminal device may request for an IP address assignment and transmit an IP address request message to the access node in step 530. The IP address creation may be carried out by the access node or a separate IP address allocation entity. In the latter case, the delay may be longer when the access node needs to communicate with the IP address allocation entity. While the IP address request is processed in block 532, the terminal device may utilize the associated delay 535 to doze or operate the other connection in block 534 and to return to scan for an IP address response message after the determined delay. In step 536, the access node transmits the IP address response message to the terminal device, and the terminal device processes the response and assumes the IP address in block 538.

Let us now consider some embodiments for acquiring information on the length of the delays associated with one or more phases of the connection establishment in the terminal device. In some embodiments, the terminal device may receive the information on the delays from the access node or a network server. In other embodiments, the terminal device may determine the information on the delays autonomously. Figure 6 illustrates a signaling diagram of an embodiment where the terminal device provides short-term estimates of future delays associated with subsequent one or more request-response message exchanges during the connection setup procedure. In an embodiment, the access node provides the terminal device with a delay estimate associated with the next request-response exchange. If the next request message is transmitted by the terminal device, the delay may encompass a time interval between the reception of the request message and transmission of a corresponding response message. If the next request message is transmitted by the access node, the delay may encompass a time interval after the reception of a response to the request message and before transmission of a subsequent message in the access node.

Referring to Figure 6, the terminal device transmits a request message to the access node in step 600 and dozes or operates the other connection in block 604 during the delay 605 while the request is processed in the access node in block 602. In step 602, the access node processes the request message, prepares the response message and estimates its processing delay. The processing delay may be estimated on the basis of at least one of the following: current processing capacity of the access node, short-term processing delay history in the access node, and type of the subsequent message in the connection establishment. If the subsequent message involves a network entity other than the access node, the estimated delay may be longer than when the subsequent message is processed by the access node only. The access node may include add an estimated radio propagation delay to the estimated processing delay, or it may omit the radio propagation delay and determine only the processing delay, e.g. from the reception of a message from the terminal device to transmission of a subsequent message to the terminal device. In step 606, the access node transmits the response message and the estimated delay to the terminal device. The indicated delay may correspond to delay 615 illustrated in Figure 6. In block 608, the terminal device processes the response and determines the duration of the dozing or operating the other link. The terminal device may apply the received estimate as such or it may reduce the delay estimate by a determined amount in order to ensure that the terminal device does not miss any messages from the access node because of overly long dozing.

In step 610, the terminal device transmits the subsequent request message to the access node and dozes or operates the other connection for the duration determined in block 608 (block 614). In block 612, the access node processes the request and determines the next delay associated with the subsequent request-response exchange. If the access node has carried out block 612 and formed the response message ready for the transmission before the expiry of the indicated delay 615, the access node may be configured to refrain from transmitting the response message before the delay 615 has expired. This ensures that the terminal device is listening when the access node transmits the response message. In step 616, the access node transmits the response message and the next delay estimate after the expiry of the delay 615, and the terminal device processes the response and determined the duration of the next dozing or operation in the other channel in block 618.

Figure 7 illustrates a process for determining the delays in the terminal device. The process may be carried out in connection with the process of Figure 2. In the embodiment of Figure 7, the terminal device receives information on the delays from the access node or from a network server in block 700. The network server may be an Access Network Discovery and Selection Function (ANDSF) of a cellular communication network or a network access server (NAS) of the wireless access network, e.g. a 802.1 1 network. The indicated delays may comprise or consist of the processing delays associated with different messages of the connection establishment procedure.

In an embodiment, the network server provides the information on the delays to the terminal device but not to the access nodes. The access nodes may apply a fixed minimum processing delay and refrain from transmitting a message to the terminal device until the minimum processing delay has expired (see block 612 in Figure 6).

The terminal device may receive the information on the delays as a bundle or a database. The information may be received as a signaling information from an access node or another network element. The information may be received in a broadcast frame such as a beacon frame or a probe response frame. The information on the delays provided in block 700 may be general delays that are substantially static values. In another embodiment, at least some of the delays are dynamic similarly to the embodiment of Figure 6. The terminal device may store the received information on the delays in a database for later reference. The database may store the delays per request-response message exchange, per access node, per wireless access network, etc. For each available wireless access network having a service set identifier, SSID, the database may provide an information element shown in Table 1 below. The number below each field represents the length of the field in octets. The information may be provided per access node of the wireless access network by including a BSS identifier

Table 1

A minimum end-to-end (E2E) delay represents a minimum delay, e.g. when the wireless access network is not loaded and/or other terminals are not accessing the network. The end-to-end delay may represent a delay between the terminal device and the network server handling the authentication, for example. The end-to-end delay corresponds to the "ping" delay, i.e. how long it takes that a short message is transmitted to the authentication server and a short response is returned from the authentication server. The minimum value may represent a determined percentage (e.g. 2%) of the shortest delays, or it may be simply the lowest delay of the last 100 operations. The terminal device may use the minimum end-to-end delay to define a maximum duration for the dozing or operating on the other connection when it wants to be minimize the probability of missing a message from the access node during the connection establishment.

An average end-to-end delay may define an average delay of the last determined number of operations. The determined number may be a configurable value and it may be set separately for the end-to-end delay measurements and the message transmissions between the access node and the terminal device. The terminal device may use the average end-to-end delay when it wants to reduce the power consumption with the increased risk of not detecting a message from the access node.

A large difference between the minimum and the average end-to-end delays may indicate that the delay has large variation and there are random effects that may change the delays. In that case, e.g. when the difference is above a determined threshold, the terminal device may prefer the minimum end-to-end delay over the average end-to-end delay.

The IP-address establishment delay may define a delay associated with the provision of IP addresses for the terminal (see delay 535 in Figure 5). If the IP addresses are created as part of the authentication, this field may be set to 0. This value could also separately indicate a delay for allocating the IP address in connection with first association between the terminal device and the wireless access network and a delay for allocating the IP address after changing from the new connection mode to the operational mode.

The number of processed messages may contain the number of authentication frames that the access node shall process in order to execute the authentication. The number of the messages used by the authentication mechanism may also be provided by identifying the authentication protocol(s). As a consequence, only one of these two fields may suffice. The authentication protocol identifier may identify the authentication mechanism used within the wireless access network. A wireless access network may utilize only a single authentication mechanism at a time. If a wireless access network utilized more than one authentication mechanism, the database may provide the delay parameters for the multiple authentication mechanisms. For instance, a wireless access network may have access node that support the FILS. These access nodes may perform a FILS authentication for FILS-capable terminal devices and another mechanism, e.g. EAP-TLS for non-FILS capable terminal devices.

The delays of the individual messages may be provided in the database as sorted according to their order during the authentication. The delays may be represented as the minimum and/or average delays representing the time that the access node and/or the authentication server processes the message.

Similar fields may be provided for messages transferred in connection with other phases of the connection establishment, e.g. the association, reassociation, reauthentication, and network discovery.

Let us now consider some embodiments where the terminal device determines the delays autonomously. In an embodiment, the terminal device uses a fixed delay estimate designed according to a minimum delay of any request- response exchange. All the exchanges comprise a transmission delay and some processing delay, so the terminal device may safely doze for a brief period even if it does not know the current processing capacity of the access node.

In another embodiment represented by a flow diagram of Figure 8, the terminal device determines the delay(s) autonomously on the basis of earlier experience of the corresponding delay(s). Referring to Figure 8, the terminal device measures the response times in the connection establishment in block 800, wherein the response time may correspond to the delay. The terminal device may measure delays associated with the request-response exchanges, e.g. any one of the delays described above. The terminal device may measure an individual delay by starting a counter when transmitting a frame to an access node and stopping the timer when the terminal device receives a subsequent frame of the connection establishment procedure from the access node. The transmitted frame may be a request or a response, and the received frame may be a request or a response. In this manner, the terminal device may measure delays associated with different phases of the connection establishment procedure.

In block 802, the terminal device stores the measured response times as measurement statistics in a local database, e.g. in a memory device of the terminal device. The local database may store the delays associated with the different phases the connection establishment procedure. The stored delays may comprise one or more of the delays of Table 1 , for example. Block 802 may comprise updating one or more of the delays stored in the local database. For example, the terminal device may recompute and update the minimum and/or average delays associated with a determined message exchange measured in block 800.

The terminal device may carry out the measurements in connection with using the delays to doze or operate the other link. The terminal device may start measuring the delay upon transmitting a message to the access node or upon receiving a positive acknowledgment to the reception of the message from the access node and, then, start the dozing or operating the other link. Upon the predetermined delay associated with the transmission of the message and stored in the local database has expired, the terminal device starts the scan for a subsequent message from the access node. Upon detecting the subsequent message, the terminal device may stop the measuring of the delay. Then, the terminal device may update the predetermined delay in the local database. As described above, the terminal device may apply a guard time to return from the dozing before the reception of the subsequent message. In connection with measuring the real delay and updating the local database, the terminal device may subtract the guard time from the measured delay before updating the delay in the local database.

In an embodiment, if any one of the delays described above is determined to be longer than a determined threshold delay, the terminal device may determine to terminate or disable the connection establishment with the access node. Upon discovering the wireless access network, the terminal device may determine whether or not one or more of the delays associated with the connection establishment with an access node of the wireless access network exceeds one or more thresholds, the terminal device may choose not to establish a connection with the access node and the wireless access network. If the terminal device detects such a prolonged delay when establishing a connection with the access node, the ternninal device may terminate the connection establishment. With respect to the embodiment of Figure 6, if the terminal device detects that a subsequent delay provided by the access node in step 606 or 616 is longer than the threshold, the terminal device may terminate the connection establishment procedure.

Figure 9 illustrates an embodiment of an apparatus comprising means for carrying out the above-mentioned functionalities of the terminal device. The terminal device may comply with specifications of an IEEE 802.1 1 network, a cellular communication network (e.g. LTE or LTE-Advanced), or another wireless network. The terminal device may also be a cognitive radio apparatus capable of adapting its operation to a changing radio environment, e.g. to changes in parameters of another system on the same frequency band. The terminal device may be or may be comprised in a computer (PC), a laptop, a tablet computer, a cellular phone, a palm computer, or any other wireless apparatus provided with radio communication capability. In another embodiment, the apparatus carrying out the above-described functionalities of the terminal device is comprised in such a wireless apparatus, e.g. the apparatus may comprise a circuitry, e.g. a chip, a processor, a micro controller, or a combination of such circuitries in the wireless apparatus.

Referring to Figure 9, the apparatus may comprise a communication controller circuitry 10 configured to control wireless communications in the wireless apparatus. The communication controller circuitry 10 may configure the establishment, operation, and termination of radio links in the apparatus, as described above. The communication controller circuitry 10 may comprise a control part 12 handling control signalling communication with respect to transmission, reception, and extraction of control or management frames including request messages, response messages, and discovery messages used when carrying out connection establishment, as described above. The control part 12 may support multiple parallel links with different access nodes and it may support concurrent operation of the multiple links. The communication controller circuitry 10 may further comprise a data part 16 that handles transmission and reception of payload data when the terminal device is associated to one or more access nodes or to one or more wireless devices.

The communication control circuitry 10 may further comprise a multipath connection controller circuitry 15. The multipath connection controller circuitry 15 may be configured to control the multipath connections in the apparatus. Upon receiving an instruction from an application executed in the apparatus to establish a connection with a network device, e.g. a server, the multipath connection controller circuitry 15 may determine whether or not to establish the connection with the network device as the multipath connection. Upon determining to establish the multipath connection, the multipath connection controller circuitry 15 may instruct the control part 12 to create an association to at least two different access nodes in parallel. The multipath connection controller circuitry 15 may have knowledge of the presence of wireless networks, and it may select the access nodes to which to associate according to a determined logic. For example, the multipath connection controller circuitry 15 may prefer to use wireless networks of different operators or internet service providers for a multipath connection. The reasoning may be that they typically have different backbone links and, thus, the probability of the throughput increase as a result of the multipath may be increased. The multipath connection controller circuitry may be configured to establish a new connection as a backup connection and/or in preparation for an upcoming handover, as described above. Other types of selection logic may naturally be used. The multipath connection controller circuitry 15 may also control the association to new access nodes and disassociation from currently serving access nodes during the operation of the multipath connection. The set of associated access nodes may need to be changed as a result of mobility of the terminal device, changing radio environment, changing congestion in the serving access nodes, etc. The use of the multipath may be invisible to the application using the multipath connection, e.g. in the multipath TCP or multipath real-time protocol.

The multipath connection controller circuitry 15 may be configured to control the operation of the links and the dozing of the wireless apparatus according to the embodiments described above. The multipath connection controller circuitry 15 may comprise a delay monitor circuitry 18 configured to monitor a current phase in the establishment of a new connection and acquire a corresponding delay from a local database 26 storing the delays associated with the different phases of the connection establishment procedure. The multipath connection controller circuitry 15 may then use the delay to control the control part 12 and/or the data part to disable operation in the new connection for the duration of the delay counted from communication of a message with an access node with which the new connection is being established. The disabling may comprise dozing completely, e.g. disabling the operation on the existing other links as well, or operating the other links and dozing towards the new connection being established. Upon expiry of the delay, the multipath connection controller circuitry 15 may configure the control part 12 to activate towards the new connection and start scanning for a subsequent message from the access node of the new link.

The circuitries 12 to 18 of the communication controller circuitry 10 may be carried out by the one or more physical circuitries or processors. In practice, the different circuitries may be realized by different computer program modules. Depending on the specifications and the design of the apparatus, the apparatus may comprise some of the circuitries 12 to 18 or all of them.

The apparatus may further comprise a memory 20 that stores computer programs 24 (software) configuring the apparatus to perform the above-described functionalities of the terminal device. The memory 20 may also store communication parameters and other information needed for the wireless communications, e.g. the database storing the different delays associated with the connection establishment procedure. The apparatus may further comprise radio interface components 22 providing the apparatus with radio communication capabilities within one or more wireless networks. The radio interface components 22 may comprise standard well-known components such as an amplifier, filter, frequency-converter, (de)modulator, and encoder/decoder circuitries and one or more antennas. The apparatus may further comprise a user interface enabling interaction with the user of the communication device. The user interface may comprise a display, a keypad or a keyboard, a loudspeaker, etc.

In an embodiment, the apparatus carrying out the embodiments of the invention in the terminal device comprises at least one processor and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to carry out the functionalities of the terminal device according to any one of the embodiments of Figures 2 to 8. Accordingly, the at least one processor, the memory, and the computer program code form processing means for carrying out embodiments of the present invention in the terminal device.

As used in this application, the term 'circuitry' refers to all of the following: (a) hardware-only circuit implementations such as implementations in only analog and/or digital circuitry; (b) combinations of circuits and software and/or firmware, such as (as applicable): (i) a combination of processor(s) or processor cores; or (ii) portions of processor(s)/software including digital signal processor(s), software, and at least one memory that work together to cause an apparatus to perform specific functions; 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. 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, e.g. one core of a multi-core processor, and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular element, a baseband integrated circuit, an application-specific integrated circuit (ASIC), and/or a field-programmable grid array (FPGA) circuit for the apparatus according to an embodiment of the invention.

The processes or methods described in Figures 2 to 8 may also be carried out in the form of a computer process defined by a computer program. The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. Such carriers include transitory and/or non-transitory computer media, e.g. a record medium, computer memory, read-only memory, electrical carrier signal, telecommunications signal, and software distribution package. Depending on the processing power needed, the computer program may be executed in a single electronic digital processing unit or it may be distributed amongst a number of processing units.

The present invention is applicable to wireless networks defined above but also to other suitable wireless communication systems. The protocols used, the specifications of the systems, their network elements and terminal devices, develop rapidly. Such development may require extra changes to the described embodiments. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1 . A method comprising: determining, in a first wireless apparatus, a delay for a connection establishment phase of a connection between the first wireless apparatus and a second wireless apparatus; causing, by the first wireless apparatus, transmission of a request message to the second wireless apparatus during a connection establishment with said second wireless apparatus; suspending, by the first wireless apparatus, scanning for a message from the second wireless apparatus during at least a portion of the determined delay in the connection establishment; and acquiring, in the first wireless apparatus, a response to the request message.

2. The method of claim 1 , wherein said suspending the scanning is performed between the transmission of the request message and the reception of the response to the request message.

3. The method of claim 1 or 2, wherein said suspending the scanning is performed after transmission of a response to the second wireless apparatus and before reception of a subsequent message from the second wireless apparatus.

4. The method of any preceding claim, wherein the determined delay is at least one of a minimum delay, an estimated delay, and a signalled delay for the connection establishment phase.

5. The method of any preceding claim, wherein the connection establishment phase comprises at least one of an authentication procedure, an association procedure, and an Internet address configuration procedure, and wherein the request message comprises at least one of an authentication request, an association request, and an Internet address configuration request, respectively.

6. The method of any preceding claim, wherein the second wireless apparatus comprises at least one of an access point, a group owner of a wireless network, mesh node of a wireless mesh network, and a base station.

7. The method of any preceding claim, wherein the determining the delay comprises at least one of receiving one or more delay parameters from at least one of the second wireless apparatus and another apparatus and determining the delay on the basis of delay statistics measured by the first wireless apparatus.

8. The method of any preceding claim, wherein the connection is established in preparation for a handover, transition, or roaming to another wireless network.

9. The method of any preceding claim, wherein the new connection is established to employ both said connection and at least one other connection in parallel to exchange data.

10. The method of any preceding claim, further comprising operating, by the first wireless apparatus, in a power-save mode during the connection establishment.

1 1 . The method of claim 10, wherein said operating in the power-save mode comprises dozing during the determined delay.

12. The method of claim 10 or 1 1 , further comprising: causing transmission of an initiation message to the second wireless apparatus after the expiry of said determined delay, wherein the initiation message initiates a service period and causes the second wireless apparatus to transmit the response to the first wireless apparatus during the service period.

13. The method of any preceding claim, wherein at least one of the first wireless apparatus and the second wireless apparatus operates in a wireless access network comprising at least one of a wireless local area network and a cellular radio communication network.

14. The method of any preceding claim, further comprising after said connection establishment of the new connection: operating the connection in a stand-by mode while carrying out data transfer over at least one other link; determining to configure the connection to change from the stand-by mode to an operational mode; changing the connection from the stand-by mode to the operational mode by transmitting a second request message to the second wireless apparatus, by suspending scanning for a response to the second request message after the transmission of the second request message and before reception of the response to the second request message, and by receiving said response to the second request message.

15. The method of any preceding claim 1 to 5, wherein the first wireless apparatus comprises at least one of an access point, a group owner of a wireless network, a mesh node of a wireless mesh network, and a base station

16. An apparatus comprising:

at least one processor; and

at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: determine a delay for a connection establishment phase of a connection between the apparatus and a second wireless apparatus; cause transmission of a request message to the second wireless apparatus during a connection establishment with said second wireless apparatus; suspend scanning for a message from the second wireless apparatus during at least a portion of the determined delay in the connection establishment; and acquire a response to the request message.

17. The apparatus of claim 16, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to suspend the scanning between the transmission of the request message and the reception of the response to the request message.

18. The apparatus of claim 16 or 17, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to suspend the scanning after transmission of a response to the second wireless apparatus and before reception of a subsequent message from the second wireless apparatus.

19. The apparatus of any preceding claim 16 to 18, wherein the determined delay is at least one of a minimum delay, an estimated delay, and a signalled delay for the connection establishment phase.

20. The apparatus of any preceding claim 16 to 19, wherein the connection establishment phase comprises at least one of an authentication procedure, an association procedure, and an Internet address configuration procedure, and wherein the request message comprises at least one of an authentication request, an association request, and an Internet address configuration request, respectively.

21 . The apparatus of any preceding claim 16 to 20, wherein the second wireless apparatus comprises at least one of an access point, a group owner of a wireless network, a mesh node of a wireless mesh network, and a base station.

22. The apparatus of any preceding claim 16 to 21 , wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to determine the delay by performing at least one of determining the delay on the basis of delay statistics measured by the apparatus and receiving one or more delay parameters from at least one of the second wireless apparatus and another apparatus.

23. The apparatus of any preceding claim 16 to 22, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to establish the connection in preparation for a handover, transition, or roaming to another wireless network.

24. The apparatus of any preceding claim 16 to 23, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to establish the new connection in order to employ both said connection and at least one other connection in parallel to exchange data.

25. The apparatus of any preceding claim 16 to 24, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to operate in a power-save mode during the connection establishment.

26. The apparatus of claim 25, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to operate in the power-save mode by dozing during the determined delay.

27. The apparatus of claim 25 or 26, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to cause transmission of an initiation message to the second wireless apparatus after the expiry of said determined delay, wherein the initiation message initiates a service period and causes the second wireless apparatus to transmit the response to the apparatus during the service period.

28. The apparatus of any preceding claim 16 to 27, wherein at least one of the apparatus and the second wireless apparatus operates in a wireless access network comprising at least one of a wireless local area network and a cellular radio communication network.

29. The apparatus of any preceding claim 16 to 28, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to perform the following after said connection establishment of the new connection: operate the connection in a stand-by mode while carrying out data transfer over at least one other link; determine to configure the connection to change from the stand-by mode to an operational mode; change the connection from the stand-by mode to the operational mode by causing transmission of a second request message to the second wireless apparatus, by suspending scanning for a response to the second request message after the transmission of the second request message and before reception of the response to the second request message, and by receiving said response to the second request message.

30. The apparatus of any preceding claim 16 to 20, wherein the apparatus comprises at least one of an access point, a group owner of a wireless network, a mesh node of a wireless mesh network, and a base station.

31 . An apparatus comprising means for carrying out all the steps of the method according to any preceding claim 1 to 15.

32. A computer program product embodied on a distribution medium readable by a computer and comprising program instructions which, when loaded into the computer, execute the method according to any preceding claim 1 to 15.