The present disclosure relates generally to connection management for dual mode user equipments (UEs) and, more particularly, to methods and apparatus for steering UEs between a
Wireless Local Area Network (WLAN) and cellular networks, or between different access points in a WLAN.
Most UEs currently on the market are dual mode UEs with the ability to connect to both cellular networks and WLANs. For example, a dual mode UE may be capable of connecting to either a 3rd Generation Partnership Project (3GPP) cellular network, such as a Long-Term Evolution (LTE) network, or to a WLAN, such as a WiFi network based on the IEEE 802.11 family of standards.
UEs as described herein may comprise or represent any device used for wireless communications. Examples of user equipment that may be used in certain embodiments of the described wireless and mobile networks are wireless devices such as mobile phones, mobile terminals, terminals, stations (e.g. in the IEEE 802.11 standard a UE may be a station (STA)), smart phones, portable computing devices such as lap tops, handheld devices, tablets, net books, computers, personal digital assistants, machine-to-machine devices such as sensors or meters (e.g. wireless devices in which there is no end user associated with the device), and other wireless communication devices that may connect to wireless and/or mobile networks.
Licensed spectrum used for 3GPP cellular networks is a premium commodity with a higher per bit cost compared to the unlicensed WLAN spectrum. Therefore, network operators are increasingly utilizing WLANs as a data offload strategy for 3GPP cellular networks. Therefore, dual mode UEs offered by most network operators dual exhibit a marked preference for connecting via a WLAN for data services rather than a 3GGP network when a WLAN is available.
Due to the inherent preference for WLANs over 3GPP cellular networks, steering a UE to connect to a WLAN is not difficult. However, most UEs dislike moving from a WLAN to 3GPP cellular network for their data service even when the user experience with the WLAN is poor. In such situations, de-authentication techniques can be used to steer a UE from the WLAN and to a 3GPP cellular network. However, forcing UEs to steer away from the WLAN using traditional de-authentication techniques may result in the UEs “blacklisting” the WLAN's Service Set Identifier (SSID). When the UE is de-authenticated, the WLAN may still be visible to the UE and the UE may attempt to reconnect to the WLAN. If the UE is de-authenticated and subsequent attempts to reconnect are ignored, the UE may “blacklist” the WLAN. The UE may also blacklist if the UE is de-authenticated three times within a five minute time window.
Once a UE “blacklists” a WLAN, the UE will consider the WLAN as unavailable. The UE will exclude the “blacklisted” WLAN when subsequently attempting to connect to a communication network even if the “blacklisted” WLAN is available. The UE will not attempt to connect back to the “blacklisted” WLAN until one of the following events happens:
(1) the user explicitly asks for the UE to connect to the “blacklisted” network;
(2) the UE is placed (or automatically goes) in a sleep mode and is then waken; or
(3) a new application is invoked that requires data connection.
The network operator has no control over UE access selection making it difficult to steer the UE back to the WLAN. The operator's inability to control access selection results in sub-optimal utilization of network resources, potential loss of revenue, and poor user experience in congested networks. Thus, for an operator who has deployed both 3GPP cellular networks and WLANs which provide overlapping coverage, it is highly desirable to control which UEs connect to which networks for data services.
The present disclosure relates to methods and apparatus for steering UEs connected to a first access point (AP) in a WLAN to a cellular network or to a second AP in the WLAN having a coverage area overlapping the coverage areas of the first AP. After determining a need to steer traffic for one or more UEs to the cellular network or second AP, the first AP lowers the transmit power of frames transmitted by the AP to effectively shrink the size of the AP's coverage area for the affected UEs. Lowering the transmit power of transmitted frames causes one or more UEs to select a nearby cellular network or another for service. In some embodiments, the first AP reduces the transmit power of management frames or other control frames.
Exemplary embodiments of the disclosure comprise methods implemented by an access point (AP) in a WLAN for steering a UE connected to a first AP in the WLAN to a cellular network to another AP in the WLAN with an overlapping coverage area. The AP determines a need to steer traffic for one or more UEs connected to the first AP to a cellular network or second AP in the WLAN. In response to determining a need to steer traffic, the AP lowers the transmit power of frames sent by the first AP in the WLAN to steer one or more UEs to connect to the cellular network or to the second AP.
In some embodiments of the method, the WLAN and the cellular network are operated by the same network operator.
In some embodiments of the method, lowering the transmit power of frames sent by the first AP in the WLAN comprise lowering the transmit power of control frames.
In some embodiments of the method, the control frames comprises at least one of beacon frames and probe response frames sent by the first AP.
In some embodiments of the method, lowering the transmit power of frames sent by the first AP in the WLAN comprises lowering the transmit power of user data frames.
In some embodiments of the method, lowering the transmit power of frames sent by the first AP in the WLAN comprises lowering the transmit power of user data frames sent by the first AP to all UEs connected to the first AP.
In some embodiments of the method, lowering the transmit power of frames sent by the first AP in the WLAN comprises lowering the transmit power of user data frames sent by the first AP to selected ones of the UEs connected to the first AP.
In some embodiments, the method further comprises dynamically lowering the transmit power of the frames during one time period and increasing the transmit power of the frames during another time period.
In some embodiments of the method, determining a need to steer traffic for one or more UEs to a cellular network or second AP in the WLAN comprises receiving instructions from a network node in the WLAN to steer traffic for the one or more UEs from the WLAN to the cellular network or to the second AP in the WLAN.
Other embodiments of the disclosure comprise a first AP in a WLAN configured to steer a UE connected to the first AP to a cellular network or second AP with an overlapping coverage area. In one embodiment, the first AP comprises a transceiver circuit and a processing circuit. The transceiver circuit is configured to communicate with one or more UEs in the WLAN. The processing circuit is configured to determine a need to steer traffic for one or more UEs connected to the first access point to a cellular network or second AP in the WLAN. The processing circuit is further configured to, in response to determining a need to steer traffic, lower the transmit power of frames sent by the first AP to steer one or more UEs to connect to the cellular network or to the second AP.
In some embodiments of the first AP, the WLAN and the cellular network are operated by the same network operator.
In some embodiments of the first AP, the processing circuit is configured to lower the transmit power of control frames.
In some embodiments of the first AP, the processing circuit is configured to lower the transmit power of beacon frames and/or probe response frames sent by the first AP.
In some embodiments of the first AP, the processing circuit is configured to lower the transmit power of user data frames.
In some embodiments of the first AP, the processing circuit is configured to lower the transmit frames of user data frames sent by the first AP to all UEs in the first AP's coverage area.
In some embodiments of the first AP, the processing circuit is configured to lower the transmit power of user data frames sent by the first AP to selected ones of the UEs connected to the first AP.
In some embodiments, the processing circuit is further configured to dynamically lower the transmit power of the frames during one time period and increase the transmit power of the frames during another time period.
In some embodiments of the first AP, the processing circuit determines a need to steer traffic for one or more UEs to a cellular network or second AP in the WLAN by receiving instructions from a network node in the WLAN to steer traffic for the one or more UEs from the WLAN to the cellular network or to the second AP in the WLAN.
Referring now to the drawings,
The WLAN 105 and a cellular network 106 may be operated by the same network operator or by different network operators. When the WLAN 105 and a cellular network 106 are jointly operated, it is to the operator's advantage to manage the UEs' connections in order to meet a number of operating goals, such as improved user experience, higher per-UE throughput, load balancing between networks, or other goals set by the operator to optimize network performance in some manner. Due to the inherent preference for a WLAN connection over the cellular network connection, the dual mode UE 103 located in the overlapping area of a WLAN 105 and a cellular network 106 will normally choose to connect to the WLAN 105 even if the connection is poor. The techniques described herein may be used to steer a UE 103 connected to an AP 102 in the WLAN 105 to the cellular network 106.
When the AP 102 receives an instruction or otherwise determines a need to steer traffic to the cellular network, the AP 102 lowers the transmit power of control frames or user data frames transmitted to the UEs 103 being steered (S315). Lowering the transmit power of the control frames or user data frames effectively shrinks the coverage area of the AP 102 and causes the affected UEs 103 to perform reselection (S320). UEs 103 close to the AP 102 or having good channel conditions may remain connected to the AP 102 while UEs 103 farther away or with poor channel conditions may switch to the cellular network 106. Thus, some of the affected UEs 103 will disconnect from the AP 102 (S325) and establish a connection with the base station 104 in the cellular network 106 (S330).
In some embodiments, the AP 102 varies the transmit power of the WLAN management frames or other control frames. Management frames include both the beacon frames as well as probe response frames. As currently implemented, UEs 103 evaluate and rank APs 102 for initial connection or handoff based on received signal power or signal quality measures. The UEs 103 generally prefer to connect to APs 102 with higher power signal quality. Therefore, lowering the transmit power of beacon frames and probe response frames will cause some of the UEs 103 to perform cell selection. More particularly, UEs near the edge of the AP's coverage area may no longer be capable of receiving the management frames. These UEs 103 near the cell edge may immediately switch to the cellular network 106. UEs 103 closer to the AP102 may still receive the management frames with lower power and therefore rank the AP 102 accordingly. This will encourage the UEs 103 to switch to the cellular network 106 to continue service.
Dynamically adjusting the management frame transmit power of the AP 102 enables the network operator to perform load balancing of UEs 103 between the WLAN 105 and cellular network 106. The transmit power of management frames may be lowered during a first time period when the AP 102 is heavily loaded to steer traffic to the cellular network 106 and raised in a second time period when traffic is light to encourage reconnection to the WLAN 105. In this embodiment, the user data frame transmit power is not changed. Thus, adjusting the management frame transmit power does not impact data transmission to those UEs 103 which remain connected to the AP 102 after a dynamic management frame power adjustment. This technique takes advantage of known UE behavior and does not require any changes to the UE 103. Because the AP 102 does not reject the UE 103, the UE 103 will not blacklist the WLAN 105.
In another embodiment, the AP 102 varies the transmit power of user data frames. Adjustment to the transmit power of user data frames may be done globally for all UEs 103 served by the AP 102, or for individual UEs 103 or groups of UEs 103. Adjusting the data frame transmission power for individual UEs 103 or groups of UEs 103 allows independent control of UE handover preferences for those UEs 103 or groups of UEs 103.
The UE 103 may measure the received signal power or signal quality of the user data frames it receives from the AP 102 and use the measurements in cell selection or handover decisions. Therefore, adjusting the transmit power of user data frames to an individual UE 103 or group of UEs 103 increases the likelihood that the UE 103 will choose to handover to the cellular network 106. UEs 103 near the cell edge may no longer be able to receive the user data frames with sufficient power or quality for decoding and connect with the cellular network 106 to maintain service. UEs 103 closer to the AP102 may still receive the user data frames frames with sufficient power but will rank the AP 102 lower. This will encourage the UEs 103 to switch to the cellular network 106 to maintain service.
The steering technique based on transmit power adjustment may also be applied to steer UEs between cells within the same WLAN 105.
The communication network 205 may comprise a WLAN 205 based on the IEEE 802.11 family of standards. A dual mode UE 203 is located in the overlapping area of the WLAN cells 210. The UE 203 may connect to the AP 202, 204 in either cell 210. In some embodiments, a WLAN controller 201 in the WLAN configures and manages the AP 202 and/or 204. While
When the AP 202 receives an instruction to offload or steer traffic to another AP 204, the AP 202 lowers the transmit power of frames transmitted to the UEs 203 being steered (S365). Lowering the transmit power of frames transmitted by the AP 202 will cause some of the UEs 203 to perform cell reselection (S370). UEs 203 close to the AP 202 or having good channel conditions may remain connected to the AP 202 while UEs 203 farther away or with poor channel conditions may switch to a second AP 204. Thus, some of the affected UEs 203 will disconnect from the AP 202 (S375) and establish a connection with the second AP 204 (S380). The transit power of frames may be dynamically lowered in a first time period (e.g. when the AP 102, 202) is heavily loaded) to steer traffic away, and raised during a second time period (e.g., when the AP 102, 202 is lightly loaded to encourage connection to the WLAN 105, 205.
As previously noted, the AP 202 may adjust the transmit power of management frames or user data frames. Management frames include both the beacon frames as well as probe response frames. Adjusting the transmit power of management frames effectively shrinks the coverage area of the AP 202. UEs 203 near the edge of the APs original coverage area may no longer be capable of receiving the management frames and therefore switch to a different AP 204 in the WLAN 105. UEs 203 that remain within the shrunken coverage area will assign a lower ranking to the AP 202 due to the lower signal power or signal quality. This ranking will encourage the UEs 203 to reselect a second AP 204 for service.
In some embodiments, the AP 202 may adjust the transmit power of user data frames transmitted to the UEs 203. The adjustment to the transmit power of the user data frames may be performed globally for all connected UEs 203 or for individual UEs 103 or groups of UEs 203. Because reselection or handover decisions are made based on received signal power or signal quality, adjustment of the transmit power of the user data frames increases the likelihood that the UEs 203 will select a second AP 204 for service. Adjustment of the transmit power of user data frames for individual UEs 103 or groups of UEs 203 gives the network operator a high degree of control over cell selection by the UEs 203.
The determining unit 522 determines the need to steer traffic for one or more UEs 103, 203 from a first AP 102, 202 in the WLAN 105, 205 to the cellular network 106 or second AP 204. The decision to steer one or more UEs 103, 203 may be based on a message received from a WLAN controller 101, 201. Alternatively, the determining unit 522 may autonomously decide to steer one or more UEs 103, 203 to the cellular network 106 or second access point 204. The transmit power adjustment unit 522 adjusts, responsive to a command or instruction from the determining unit 524, the transmit power of control frames or user data frames transmitted to one or more UEs 103, 203. As previously noted, the transmit power adjustments may be applied to control frames or user data frames for all UEs 103 within the coverage area of the AP 102, 202. Alternatively, the transmit power adjusting unit may adjust the transmit power of control frames or user data frames transmitted to individual UEs 103, 203 or groups of UEs 103, 203.
The steering techniques described herein enable traffic steering without risk that the UEs 103, 203 being steered will blacklist the WLAN 105, 205. The steering techniques takes advantage of known UE behavior and does not require any changes to the UE 103. Because the AP 102 does not reject the UE 103, the UE 103 will not blacklist the WLAN 105.
The present invention may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the invention. The present embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.
This application claims priority under 35 U.S.C. §119(e) to Provisional Patent Application Ser. No. 61/943,071, filed Feb. 21, 2014, the entire contents of which are incorporated by reference herein.
Filing Document | Filing Date | Country | Kind |
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PCT/IB2014/065221 | 10/10/2014 | WO | 00 |
Number | Date | Country | |
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61943071 | Feb 2014 | US |