GB2502175A

GB2502175A - Adjusting backoff time period based on current network load

Info

Publication number: GB2502175A
Application number: GB1301636.5A
Authority: GB
Inventors: Brian Alexander Martin; Keiichi Kubota
Original assignee: Renesas Mobile Corp
Current assignee: Renesas Electronics Corp
Priority date: 2012-05-14
Filing date: 2013-01-30
Publication date: 2013-11-20
Also published as: GB2502093A; GB201301636D0; GB201208563D0

Abstract

Typically, if a mobile device is unable to access a random access communication channel due to contention by other mobile devices, a random back off time is generated and the device is prevented from attempting to communicate again during this time. This may be inefficient depending on current network loading. To overcome this a mobile device can receive an indication to use a longer back off time during periods of heavy network load and a shorter time period during less congested times. Data can be maintained to be used in determination of a back-off time period by a user terminal based on current loading of the communication network. The data comprises at least one extended acquisition indicator (E-AI) of a first type, the E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal; and transmit the maintained data for use controlling access to the E-DCH by the user terminal.

Description

Wireless Communication System and Method

Technical Field

The present invention relates to wireless communication systems, methods, devices and computer programs, and more specifically relates to controlling access to resources of a communication network by a user terminal. The embodiments relate to a mechanism for controlling access request for enhanced dedicated channel by user terminals.

Background

The following meanings for the abbreviations used in this specification apply: AICH acquisition indicator channel BCCH Broadcast Control Channel CN core network DTCH dedicated transport channel E-AI Extended acquisition indicator E-DCH Enhanced dedicated channel eNB enhanced node B eNodeB enhanced node B NB Nodc B NW Network PRACH Physical random access channel RACH Random access channel RB radio bearer RNC radio network controller RRC radio resource control SI System Information SIB System Information Block TTI Transmission Time Interval TIE user equipment IJL uplinlc In accordance with the Release 7 third generation partnership project (3GPP) standards, wireless transmit'receive units or user terminals may be in either an idle state or a connected state. Based on the user terminal mobility and activity while in the connected state, a radio access network (RAN) may direct the user terminal to transition between a number of sub-states: Cell PCH, URA PCH, Cell FACH, and Cell DCH states. User plane communication between the user terminal and the RAN is only possible while in Cell_EACH and Cell DCH statcs. The Cell DCH statc is characterized by dedicated channels in both uplink and downlink. On the user terminal side, the Cell DCH state corresponds to continuous transmission and reception, but requires more power. The Cell FACH state does not use dedicated channels and thus allows befter power consumption, but provides a lower uplink and downlink throughput.

In pre-Release 8 3GPP standards, uplink communications are achieved through a random access channel (RACH) mapped to a physical random access channel (PRACH). The RACH is a contention-based channel and a power ramp-up procedure is used to acquire a channel and to adjust transmit power. RACH is a shared channel used for an initial access to obtain dedicated resources or to transmit small amount of data.

In Release 8 3GPP standards the uplink transmission mechanism in Cell FACH state was modified by combining the RACH channel acquisition stage with an enhanced dedicated channel (E-DCH). The procedure is known as enhanced uplink for Cell FACH and IDLE mode. A user terminal that wants to access a channel randomly selects a signature and transmits a RACH preamble to a Node B during a randomly selected access slot at a certain transmit power level. The Node B would choose an E-DCH resource from a set of common E-DCH resources that are shared amongst all user terminals, and responds to a user terminal channel access request by assigning one of the shared resources. The user terminal then starts transmission over the assigned E-DCH transport channel.

If the associated resource is unavailable, the Node B responds with a negative acknowledgement (NACK) on an acquisition indicator channel (AICH). This triggers a back-off mechanism at the user terminal. After expiry of the back-off timer, a preamble ramping cycle count is incremented and the procedure starts again. This cffectivcly rcstarts the RACH proccdurc at a latcr time. If thc RACH prcamble from the user terminal is not detected at the Node B, no extended acquisition indicator (E-Al) is transmitted on the AICH. If the user terminal fails to receive an E-A1 after transmission of the RACH preamble, the user terminal tries again in a subsequent access slot with a randomly chosen signature and a higher transmit power, up to the maximum number of times.

Recently it has been proposed for Release 11 3GPP standards, the Node B request the user terminal to faliback onto 3GPP Release 99 PRACH by transmitting a rclcvant E-AI. In the event that the user terminal's access request relates to a transmission on the common control channel (CCCH) or the dedicated control channel (DCCFI), the user terminal may fallback to R99 PRACH. However, if the uscr terminal's requcst rclatcs to transmission of dedicated traffic channel data on the E-DCH, tim user tcrminal would apply the back-off mechanism, as dcscribcd above, in which the user terminal would retransmit the RACH preamble after expiry of a random back-off timer.

However, the back-off timer is randomly selected by user terminals and it does not enable efficient use of network resources.

Embodiments are directed towards providing an improved back-off mechanism.

Summary

In a first exemplary embodiment of the inventioll there is provided an apparatus for use in controlling access to resources of a communication network by a uscr terminal, thc apparatus comprising a processing systcm arranged to cause the apparatus to: maintain data to be used in determination of a back-off time period by a user terminal based on load on the communication network, said data comprising at least one cxtcnded acquisition indicator (E-AI) of a first type, said E-AT of thc first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal; and transmit said maintained data for use controlling access to said E-DCH by said user terminal.

In a second exemplary embodiment of the invention there is provided a method of controlling access to resources of a communication network by a user terminal, the method comprising: maintaining data to be used in determination of a back-off time period by a user terminal based on load on the communication network, said data comprising at least one extended acquisition indicator (h-Al) of a first type, said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal; and transmitting said maintained data for use controlling access to said E-DCH by said user terminal.

The first and second exemplary embodiments are most conveniently implcmcnted in a radio network controller. Embodiments also include a computer program comprising a set of instructions, which, when executed by a radio network controller, cause the radio access node to perform a method according to the second embodiment.

In a third exemplary embodiment of the invention there is provided an apparatus for use in controlling access by a user terminal to a communication network, the apparatus comprising a processing system arranged to cause the apparatus to: maintain at least one extended acquisition indicator (E-AI) of a first type, each said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal; and in response to receiving a random access channel (RACH) preamble, said RACH preamble being indicative of a request by said user terminal to access said E-DCH, select and transmit data indicative of a said E-AI of the first type, said data transmitted to the user terminal comprising data to be used by the user terminal to identify a back-off time period for use in transmission of a further RACH preamble.

In a fourth exemplary embodiment there is provided a method of controlling access by a user terminal to a communication network, the method comprising: maintaining at least one extended acquisition indicator (h-Al) of a first type, each said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal; and in response to receiving a random access channel (RACH) preamble, said RACH preamble being indicative of a request by said user terminal to access said E-DCH, selecting and transmitting data indicative of a said h-Al of the first type, said data transmitted to the user terminal comprising data to be used by the user terminal to identify a back-off time period for use in transmission of a flirt her RACH preamble The third and fourth exemplary embodiments are most conveniently implemented in a base station. Embodiments also include a computer program comprising a set of instructions, which, when executed by a base station, cause the base station to perform a method according to the fourth embodiment.

In a fifth exemplary embodiment of the invention there is provided an apparatus for use in controlling access by a user terminal to a communication network, the user terminal being configured in a CELL FACH state, the apparatus comprising a processing system arranged to cause the apparatus to: receive data indicative of an extended acquisition indicator (E-AI) of a first type, said E-AT of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by said user terminal; identif' a back-off time period on the basis of a load condition on the communication network and the received E-AI; and transmit data indicative of a random access channel (RACH) preamble in response to expiry of said identified back-off time period, whereby to request access to said E-DCH by said user terminal.

In a sixth exemplary embodiment there is provided method of controlling access by a user terminal to a communication network, the user terminal being configured in a CELL EACH state, the method comprising: receiving data indicative of an extended acquisition indicator (F-Al) of a first type, said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by said user terminal; identifying a back-off time period on the basis of a load condition on the communication network and the received E-Al; and transmitting data indicative of a random access channel (EACH) preamble in response to expiry of said identified back-off time period, whereby to request access to said E-DCH by said user terminal.

The fifth and sixth exemplary embodiments are most conveniently implemented in a user terminal. Embodiments also include a computer program comprising a set of instructions, which, when executed by a user terminal, cause the user terminal to perform a method according to the sixth embodiment.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 is a simplified block diagram of a communication network within which embodiments operate.

Figure 2 isa logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with exemplary embodiments.

Figure 3 is a flow diagram that illustrates the various steps performed by TJE, Node B and RNC according to embodiments.

Figure 4 is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with exemplary embodiments.

Figure 5 is a ogic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with exemplary embodiments.

Figure 6 is a simplified block diagram of various network devices, which are exemplary electronic devices suitable for use in practicing the exemplary embodiments.

Detailed Description

Embodiments are concerned with controlling access network resources by a user terminal in a communication network.

In the following, examples and embodiments of the present invention are described with reference to the drawings. For illustrating the present invention, the examples and embodiments will be described in connection with a ceflular communication network based on a 3GPP-type cellular system, such as universal mobile telecommunication system. However, it is to be noted that the present invention is not limited to an application using such types of communication system, but is also applicable in other types of communication systems and the like.

A basic system architecture of a communication network where examples of embodiments of the invention are applicable may comprise a commonly known architecture of one or more communication networks comprising a wired or wireless access network subsystem and a core network. An exemplary communication network will now be described with reference to Figure 1. The communication network 10 may comprise a Node B 80 and a radio network controller (RNC) 30. A user terminal 50 or another wireless transmit/receive device having a similar function, such as a modem chipset, a chip, a module etc., which can also be part of a user terminal or attached as a separate element to a user terminal, or the like, is able to communicate with the Node B 80 via one or more channels for transmitting several types of data.

The communication network 10 may additionally be in communication with various mobility management entities (not shown), which facilitate mobility of user terminals across various carriers, and/or network management entities, which manage resources of the communication network.

The general functions and interconnections of the described elements, which also depend on the actual network type, are known to those skilled in the art and described in corresponding specifications, so that a detailed description thereof is omitted herein. However, it is to be noted that several additional network elements and signalling links may be employed for a communication connection to or from user terminals, Node Bs or RNCs, besides those described in detail herein below.

Referring to Figures 2 and 3, in accordance with an exemplary embodiment, the RNC 30 maintains data to be used in determination of a back-off time period by the user tenyiinal 50 based on load on the communication network. The maintained data comprises at least one extended acquisition indicator (E-AI) of a first type (step 201); as is well known in the art, E-AIs represent a set of values corresponding to a set of enhanced dedicated channel (E-DCFI) resource configurations, and are for use by user terminals in configuring transmissions on the E-DCH. The E-AI of the first type according to an embodiment indicates inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal 50. In particular, the E-AI of the first type is either indicative of a negative acknowledgement, i.e. denial of access to requested resources, and/or a request to fallback onto the 3GPP Release 99 (R99) PRACI-I.

Thereafter, the RNC 30 transmits the maintained data for use in controlling access to the E-DCH by the user terminal 50 (step 203). The RNC 30 may transmit the maintained data for receipt by the Node B 80 andlor the nser terminal 50. In the case of the Node B 80, the maintained data can be used when responding to a random access channel (RACI-1) preamble from the user terminal 50.

More particularly, the Node B 80 may transmit data, derived from the maintained data received from the RNC 30, to be used by the user terminal 50 to identify a back-off time period for use in transmission of a further RACH preamble, thereby controlling transmission of a further EACH preamble by the user terminal 50.

In cffcct, the RNC 30 enables the Node B 80 to control retransmission of a further EACH preamble on a physical channel, such as the physical random access channel (PRACH) or the enhanced dedicated physical data channel (E-DPDCFI), by the user terminal 50. Thus, by transmitting appropriate data, the Node B 80 can cause the user terminal 50 to identify a longer back-off time period during congested periods and a shorter back-off time period associated when the network is relatively less congested, thereby enabling Node Bs to make efficient use of network resources and alleviate network congestion.

In at least some arrangements, the R14C 30 associates a predetermined back-off time period with the extended acquisition indicator (B-Al) of the first type, in which case the data transmitted by the RNC may comprise the predetermined back-off time period. Advantageously, the Node B 80 may then control the length of the back-off time period by selecting and transmitting an appropriate E-AI. Thus, the RNC 30 enables the Node B 80 to directly control the length of the back-off time period by associating predetermined back-off time periods with the E-Als of the first type.

Alternatively, the data maintained at the RNC 30 may comprise data indicative of a load condition to be maintained in the communication network 10, in which case the data transmitted by the RNC 30 comprises data indicative of the load condition.

Accordingly, the Node B 80 may cause identification of the back-off time period by the user terminal 50 in accordance with the load condition on the network. In this way, the Node B 80, and more generally the network 10, has a direct influence over the length of the back-off time period identified at the user terminal 50 for use in the back-off mechanism.

In at least some arrangements, the load condition transmitted by the RNC 30 to the user terminal 50 may comprise data indicative of a load parameter for use by the user terminal SO in identification of the back-off time period for use in the aforementioned back-off mechanism. Thus, the RNC 30 may indicate a state of the network 10 or a traffic profile on the aforementioned physical channel and/or the aforementioned E-DCH, thereby causing the user terminal 50 to select an appropriate back-off time period for use in the back-off mechanism. In effect, the RNC 30 indirectly controls the back-off mechanism by means of a load parameter that is transmitted to the user terminal 50, and used by the user terminal 50 to select the back-off time period. The RNC 30 may transmit the load condition in a system information block (SIB) message, such as the SIB? message, for example in a conventional information element in the SIB7 message, such as the interference information element, or an information element may added in the SIB? message thercfor.

In effect, the RNC 30 transmits data to the user terminal 50 that controls the length of back-off time period apphed by the user terminal 50, which is in direct contrast with the prior art, where the back-off time period is randomly selected without any regard for the transmission received from the RNC 30. Thus, the embodiments provide a network controlled back-off mechanism, which utilises network resources efficiently.

It will be appreciated that the back-off mechanism per embodiments is either directly controlled by the network 10 or is operated under the influence of conditions specified by the network 10; as a result the network 10 can manipulate its operation in order to ensure efficient usage of network resources and alleviating network congestion.

In at least some arrangements, the RNC 30 may assign one or more E-AIs of the first type on a per user terminal basis. In particular, the RNC 30 may assign at least one E-AI of the first type to the user terminal 50, thereby varying the back-off time periods for specific user terminals. Thus, the RNC 30 can prioritise one user terminal over another user terminal by associating E-AIs having a shorter back-off time period therewith. For example, user terminals corresponding to emergency services may be prioritised. In response to assigning the E-AI of the first type, the RNC 30 may transmit data indicative of the assignment for use in controlling access to the E-DCH by the user terminal 50. For completeness, the RNC 30 may transmit data indicative of the assignment for receipt by the Node B 80 and/or the user terminal 50.

Alternatively, the RNC 30 may assign one or more E-AIs of the first type on a per cell basis, in which case the RNC 30 may assign at least one E-AI of the first type to the Node B 80, and transmit data indicative of the assignment for use in controlling access to the E-DCH by user terminals being served by the Node B 80, thereby controlling cell resources.

As mentioned above, user terminals may transmit a RACH preamble to request access to network resources, such as for dedicated traffic channel (DTCH) transmissions on the E-DCH, or for transmissions on common control channel (CCCH) or dedicated control channel (DCCH), to the Node B 80. An overview of the steps performed by the Node B 80 in response to receiving the aforementioned RACH preamble on the aforementioned physical channel will now be described with reference to Figure 4.

The Node B 80 may maintain at least one of the aforementioned E-AI of the first type (step 401), for example in response to receipt of data indicative of the E-AI of the first type at step 203. Returning to Figure 3, in response to receiving a RACH preamble (step 301), the Node B 80 may select and transmit data indicative of the F-Al of the first type. These data that are transmitted to the user terminal 50 include data to be used by the user terminal 50 to identi' a back-off time period for use in transmission of a further RACH preamble (step 403). In at least some arrangements, the back-off time period can be derived from the selected F-Al of the first type. In this case, the E-AI of the first type may have an associated predetermined back-off time period, and the user terminal 50 identifies the back-off time period for use in the aforementioned back-off mechanism on the basis of the received E-Al.

The Node B 80 may maintain an association between each of a plurality of E-Als of the first type and corresponding back-off time periods for use in controlling access to the E-DCH. In this case, the Node B 80 may select an E-Al for transmission to the user terminal 50 at step 403 on the basis of the back-off time period associated therewith. For example, the Node B 80 may select and transmit an F-Al of the first type having a longer back-off time period during a congested period, and select and transmit an E-AI of the first type having a shorter back-off time period when the network 10 is relatively less congested, thereby enabling Node Bs to effectively control the aforementioned back-off mechanism. Alternatively, the Node B 80 may select an E-Al of the first type on the basis of a probable availability of resources on the E-DCH, thereby actively managing availability thereof For completeness, the Node B 80 may receive data indicative of the association between the E-AIs of the first type and the predetermined back-off time period from a core network entity, such as the RNC 30.

In at least some arrangements, the data transmitted by the Node B 80 to the user terminal 50 may comprise data indicative of a load parameter for use by said user terminal 50 in identification of the back-off time period for use in the aforementioned back-off mechanism. In which ease, the Node B 80 indirectly controls the back-off mechanism by means of a load parameter that is transmitted to the user terminal 50, and used by the user terminal 50 to select the back-off time period.

In effect, the Node B 80 directly or indirectly controls the length of back-off time period applied by the user terminal 50, which is in direct contrast with the prior art, where the back-off time period is randomly selected without any regard for the transmission received from the Node B 80. Thus, the embodiments provide a network controlled back-off mechanism, which enables the Node B 80 to control the rate at which repeat requests are transmitted by user terminals, thereby controlling traffic on the physical channel, and reducing likely conflicts thereon.

In response to receiving a further RACH preamble from the user terminal 50, the Node B 80 may select and transmit a further E-Al of the first type on the basis of a further load condition on the network 10, for example the load condition that applies at the time of receipt of the further RACH preamble. Thus, the Node B 80 may continually adapt the back-off time period for RACFI preamble retransmissions on the basis of a current load condition on the network, and as a result make optimal use of network resources and prevent congestion.

The Node B 80 may additionally maintain at least one E-AI of a second type, different to the E-AIs of the first type. The E-AI of the second type is indicative of accessibility of the E-DCH by the user terminal 50. Accordingly, in response to receiving the further RACFI preamble, the Node B 80 may select and transmit the E-All of the first or second type. For example, in the event that the communication network 10 is determined to be capable of accommodating a request associated with the further RACH preamble, the Node B 80 may transmit an B-Al of the second type, whereby to cause the user terminal 50 to access the requested resource, such as the F-DCH.

An overview of the steps performed by the user terminal 50 in response to receiving an F-Al of the first type will now be described with reference to Figure 5.

While being configured in the CELL FACH state, the user terminal 50 may receive data indicative of an B-Al of the first type (step 501). As described above, the E-AI of the first type may be indicative of a denial of access to the requested resource or may be a request to failback onto R99 PRACH. In the event that the user terminal's 50 request relates to transmission on the aforementioned CCCH or the aforementioned DCCH, the user terminal 50 may fallback onto the R99 PRACH, i.e. fallback onto the R99-type access technology, such as global system for mobile communications (GSM), to transmit data.

In the event that the user terminal's 50 access request relates to transmission of DTCH data on the aforementioned E-DCH, the user terminal 50 may invoke a back-off mechanism. In accordance with the back-off mechanism, the user terminal 50 identifies a back-off time period on the basis of a load condition on the communication network 10 and the received E-AI of the first type (step 503).

Subsequent to the expiry of the back-off time period (step 303), the user terminal 50 may transmit data indicative of a further RACH preamble (step 505), whereby to request access to the E-DCH. Therefore, the back-off mechanism per the embodiments enables selection of a back-off time period in accordance with a load condition on the network 10, thereby enabling efficient usage of network resources.

The user terminal 50 may identify the load condition on the network 10 from the received E-Al of the first type. For example, the received E-AT of the first type may be associated with a predetermined load condition, and the user terminal 50 may identif' the load condition on the network and thereafter configure a back-off period.

As discussed above, each of the B-AIs of the first type may be associated with a predetermined back-off time period, in which case the user terminal 50 may identify the back-off time period for use in the back-off mechanism on the basis of the back-off time period associated with the received E-AI of the first type. To facilitate such an identification of an appropriate back-off time period, the user terminal 50 may be configured to receive and store data indicative of the plurality of E-AIs of the first type and the back-off time periods associated with them from the RNC 30 (step 203) or the Node B 80. By provisioning the data indicative of the E-AIs of the first type and the back-off time periods associated therewith, the RNC 30, and more generally the network 10, can actively control the rate at which the user terminal 50 retries to access the E-DCH. For completeness, it is noted that either of the RNC 30 or the Node B 80 may provision data indicative of the E-AIs of the first type and their associated back-off time periods to the user terminal 50 via a system information message andlor via a dedicated signalling information message.

In at least some arrangements, the user terminal 50 may receive data indicative of the aforementioned load parameter for usc in detection of the load condition on the network 10, e.g. from the Node B 80 or the RNC 30. The load parameter may comprise data indicative of one or more of network criteria, which can be used by the user terminal to identi the load condition on the network 10. In some arrangements, the load parameter may, for example, comprise a value corresponding to one or more of the network criterion.

Alternatively or additionally, the user terminal 50 may maintain a count of received of the E-AI of the first type for usc in detection of the load condition on the network. For example, the user terminal 50 may consider a high number of received E-AJ of the first type to be indicative of congestion on the network and adjust the back-off time accordingly. More specifically, this count value may be used to identify the back-off time period for use in the back-off mechanism. For example, the user terminal 50 may select a random back-off time period between a predetermined minimum and a predetermined maximum back-off time period in response to receiving a first E-AI of the first type, and thereafter scale the random back-off time period on the basis of a predetermined scaling factor in response to receipt of a subsequent E-AI of the first type. Alternatively, the user terminal 50 may receive data indicative of an initial back-off time period from, for example, the Node B 80, and thereafter the user terminal 50 may scale the initial back-off time period on the basis of the count and a predetermined scaling factor. In this way, the user terminal 50 reacts to repeat indications of inaccessibility of the E-DCH by extending the back-off time periods accordingly. In effect; repeat indications of the inaccessibility of the E-DCII are considered to be indicative of congestion on the network 10, and the user terminal 50 may adapt the back-off time period accordingly. It is to be noted that the user terminal may maintain the count in relation to any E-AI of the first type or on the basis of a particular E-AE of the first type.

It will be appreciated that the count based identification of the back-off time period can be used by user terminals in the absence of data indicating an association betwccn thc E-AIs of the first type and thc back-off timc periods associatcd thcrcwith, or may be used in combination therewith. Similarly, the load parameter can be used in absence of the data indicating association between E-Als of the first type and back-off time periods associated therewith, or may be used in combination therewith.

As described above, the user tenninal 50, in response to the expiry of the back-off time period, may transmit a further RACH preamble whereby to request access to the E-DCH, which may cause receipt of a further E-A1 of the first or second type. In response to receiving the E-AI of the second typ; the user terminal 50 may transmit data on the E-DCH in accordance with the received E-AE of the second type.

The E-A1 of the second type is additionally indicative of an E-DCH resource configuration, and may be used by user terminals in configuring transmissions on the E-DCH.

It will bc apprcciatcd by those skilled in the art that the user tcrminal 50 may receive the E-M of the second type in response to transmitting the RACH preamble for the first time or in response to any subsequent transmissions of the RACH preamble. hi some arrangements, the user terminal 50 may reset the aforementioned count of received E-AIs of the first type in response to receiving the E-AE of the second type.

Figure 2 is a logic flow diagram which describes, bmadly, the above exemplary embodiments from the perspective of a RNC 30.

Figure 4 is a logic flow diagram which describes, bmadly, the above exemplary embodiments fix,m the perspective of a Node B 80.

Figure 5 is a logic flow diagram which describes, broadly, the above exemplary embodiments from the perspective of a user terminal 50.

Figures 2, 4 and 5 represent results from executing a computer program or an implementing algorithm stored in the local memory of the RNC 30, the Node B 80 and the user terminal 50 respectively as well as illustrating the operation of a method and a specific manner in which the processor and memory with computer program/algorithm are configured to cause the RNC 30, the Node B 80 and the user terminal 50 respectively (or one or more components thereoD to operate. The various blocks shown in these Figures may also be considered as a plurality of coupled logic circuit elements constructed to carry out the associated frmnction(s), or specific result or function of strings of computer program code stored in a computer readable memory. Such blocks and the functions they represent are non-limiting examples, and may be practiced in various components such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry (as weH as possibly firmware) for embodying at east one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.

Reference is now made to Figure 6 for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing the exemplary embodiments of this invention. In Figure 6 a Node B 80 is adapted for communication over a wireless link with a user terminal 50, such as a mobile terminal. The Node B 80 may be a macro Node B, an eNodeB, a remote radio head or relay station, or other type of base station/cellular network access node.

The user terminal 50 include processing means such as at least one data processor (DP) 50A, storing means such as at least one computer-readable memory (MEM) SOB storing at least one computer program (PROG) SOC, and also communicating means such as a transmitter TX SOD and a receiver RX 50E for bidirectional wireless communications with the Node B 80 via one or more antennas S OF.

The Node B 80 includes its own processing means such as at least one data proccssor (DP) 80A, storing mcans such as at icast onc computcr-rcadablc mcmory (MEM) SOB storing at least one computer program (PROG) 80C, and communicating means such as a transmitter TX 80D and a receiver RX 80E for bidirectional wireless communications with othcr dcviccs undcr its control via onc or morc antcnnas 80F.

There is a data andlor control path, termed at Figure 6 as a control link which in the 3GPP cellular system may be implemented as an Si interface, coupling the Node B 80 with thc RNC 30, and over which the RNC 30 and the Node B 80 may exchange control messages, such as data indicative of the association between the E-AIs of the first type and the back-off time periods associated therewith. The Node B 80 also has stored in its local memory at SOB the database which has the data indicative of the association between the E-AIs of the first type and the back-off time periods associated therewith, as the case may be for the various embodiments detailed above.

Similarly, the RNC 30 includes processing means such as at least one data processor (DP) 30A, storing means such as at least one computer-readable memory (MEM) 30B storing at least one computer program (PROG) 30C, and communicating means such as a modem 30H for bidirectional communication with the Node B 80 over the control link.

While not particularly illustrated for the user terminal 50, the Node B 80 and the RNC 30, those devices are also assumed to include as part of their wireless communicating means a modem which may be inbuilt on a radiofrequeney RE front end chip within those devices 50, 80, 30 and which chip also carries the TX 50D/SOD/30D and the RX 50E/SOE/30E.

At least one of the PROGs SOC in the user terminal 50 is assumed to include program instructions that, when executed by the associated DP SOA, enable the device to operate in accordance with the exemplary embodiments of this invention, as detailed above. The Node B 80 and the RNC 30 also have software stored in their respective MEMs to implement certain aspects of these teachings. Tn these regards the exemplary embodiments of this invention may be implemented at least in part by computer software stored on the MEM SOB, SOB, 30B which is executable by the DP SOA of the user terminal 50, DP SOA of the Node B 80 and/or DP 30A of the RNC 30, or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware). Electronic devices implementing these aspects of the invention need not be the entire devices as depicted at Figure 6, but exemplary embodiments may be implemented by one or more components of same such as the above described tangibly stored software, hardware, firmware and DP, or a system on a chip SOC or an application specitic integrated circuit ASIC.

Various embodiments of the computer readable MEMs SOB, 80B, and 30B include any data storage technology type which is suitable to the local technical environment, including but not limited to semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, removable mcmory, disc mcmory, flash memory, DRAM, SRAM, EEPROM and the like. Various embodiments of the DPs 50A, 30A and SOA include but are not limited to general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and multi-core processors.

Further, some of the various features of the above non-limiting embodiments may be used to advantage without the corresponding use of other described features.

The foregoing description shou'd therefore be considered as mer&y illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

Claims 1. An apparatus for use in controlling access to resources of a communication network by a user terminal, the apparatus comprising a processing system arranged to cause the apparatus to: maintain data to be used in determination of a back-off time period by said user terminal based on load on the communication network, said data comprising at least one extended acquisition indicator (E-Al) of a first type, said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by thc uscr tcrminal; and transmit said maintained data for use controlling access to said E-DCH by said user terminal.
2. An apparatus according to claim I, wherein the processing system is arranged to cause the apparatus to: associate a predetermined back-off time period with said extended acquisition indicator (E-AI) of the first type, wherein said transmitted data further comprises said predetermined back-off period.
3. An apparatus according to claim 1, wherein the maintaincd data comprises data indicative of a load condition to be maintained in the communication network, wherein said transmitted data further comprises data indicative of said load condition.
4. An apparatus according to claim 1, wherein the processing system is arranged to: assign at least one of a plurality of said E-AIs of the first type to the user terminal; and transmit data indicative of said assignment for use in controlling access to said E-DCFI by said user terminal.
5. An apparatus according to claim I, wherein the processing system is arranged to: assign at least one of a plurality of said E-Als of the first type to a cell; and transmit data indicative of said assignment for use in controlling access to said E-DCH by said user terminal while being served by said cell.
6. A radio network controller comprising an apparatus according to any one of claim ito claim 5.
7. An apparatus for use in controlling access by a user terminal to a communication network, the apparatus comprising a processing system arranged to cause the apparatus to: maintain at least one extended acquisition indicator (E-AI) of a first type, each said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal; and in response to receiving a random access channel (BACH) preamble, said RACH preamble being indicative of a request by said user terminal to access said E-DCH, select and transmit data indicative of a said E-AI of the first type, said data transmitted to the user terminal comprising data to be used by the user terminal to identi' a back-off time period for use in transmission of a further BACH preamble.
8. An apparatus according to claim 7, wherein said data transmitted to the user terminal comprises data enabling the user terminal to identify said back-off time period from the selected E-AI of the first type.
9. An apparatus according to claim 8, wherein the processing system is arranged to maintain an association between each said E-A1 of the first type and a said back-off time period for use in controlling access to said E-DCH.
10. An apparatus according to claim 9, wherein the processing system is arranged to receive data indicative of said association from a core network entity for use in controlling access to said E-DCH.
11. An apparatus according to claim 7, wherein said data transmitted to the user terminal comprises data indicative of a load parameter for use by said user terminal in identification of said back-off time period.
12. An apparatus according to any one of claim 7 to claim 11, wherein the processing system is arranged to: maintain at least one E-A1 of a second type, different to the first type, each said E-AI of the second type being indicative of accessibility of said E-DCH by the user terminal; and in response receiving said further RACH preamble, select and transmit a said E-AI of the first or second type.
13. An apparatus according to claim 12, wherein, in the event that the communication network is determined to be capable of accommodating a request associated with the further RACH preamble, the processing system is arranged to cause the apparatus to transmit a said E-AI of the second type, whereby to cause said user terminal to access said E-DCH.
14. A base station comprising an apparatus according to any one of claim 7 to claim 13.
15. An apparatus for use in controlling access by a user terminal to a communication network, the user terminal being configured in a CELL FACFI state, the apparatus comprising a processing system arranged to cause the apparatus to: receive data indicative of an extended acquisition indicator (E-AI) of a first type, said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by said user terminal; identify a back-off time period on the basis of a load condition on the communication network and the received E-AI; and transmit data indicative of a random access channel RACH) preamble in response to expiry of said identified back-off time period, whereby to request access to said E-DCH by said user terminal.
16. An apparatus according to claim 15, wherein the processing system is arranged to detect the load condition from said received E-Al of the first type.
17. An apparatus according to claim 15 or claim 16, wherein said E-AI of the first type is one of a plurality of E-AI, each said E-AI being associated with a predetermined back-off time period, and the processing system is arranged to identify said back-off time period on the basis of said received E-A1I.
1K An apparatus according to claim 17, wherein the apparatus is arranged to receive and maintain data indicative of said plurality of E-ATs of the first type and said predetermined back-off time period associated therewith for use in said identification of the back-off time period.
19. An apparatus according to 15, wherein the processing system is arranged to receive data indicative of a load parameter for use in said detection of said load condition on the communication network.
20. An apparatus according to claim 15, wherein the processing system is arranged to maintain a count of said received E-AI of the first type for use in said detection of said load condition on the communication network.
21. An apparatus according to claim 20, wherein the processing system is arranged to perform said identification of the back-off time period on the basis of said count.
22. An apparatus according to any one of claim 15 to claim 21, wherein, responsive to receiving an E-AI of a second type, different to the first type, said E-AI of the second type being indicative of accessibility of said E-DCH by the user terminal, the processing system is further arranged to transmit data on said E-DCH in S accordance with said received E-AI of the second type.
23. An apparatus according to any one of claim 15 to claim 22, wherein the apparatus comprises a modem.
24. A mcthod of controlling access to resources of a communication network by a user terminal, the method comprising: maintaining data to be used in determination of a back-off time period by said user terminal based on load on the communication network, said data comprising at least one extended acquisition indicator (E-AI) of a first type, said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal; and transmitting said maintained data for use controlling access to said E-DCI-1 by said user terminal.
25. A method according to claim 24, in which the method comprises associating a predetermined back-off time period with said extended acquisition indicator (E-AI) of the first type, wherein said transmitted data ffirthcr comprises said predetermined back-off period.
26. A method according to claim 24, in which said maintained data comprises data indicative of a load condition to be maintained in the communication network, and the method comprises transmitting data indicative of said load condition.
27. A method according to claim 24, in which the method further comprises: assigning at least one of a plurality of said E-Als of the first type to the user terminal; and transmitting data indicative of said assignment for use in controlling access to said E-DCH by said user terminal.
28. A method according to claim 24, in which the method further comprises: assigning at least one of a plurality of said E-AIs of the first type to a cell; and transmitting data indicative of said assignment for use in controlling access to said E-DCH by said user terminal while being served by said cell.
29. A method of controlling access by a user terminal to a communication network, the method comprising: maintaining at least one extended acquisition indicator (E-Al) of a first type, each said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal; and in response to receiving a random access channel (RACH) preamble, said RACH preamble being indicative of a request by said user terminal to access said E-DCH, selecting and transmitting data indicative of a said E-AI of the first type, said data transmitted to the user terminal comprising data to be used by the user terminal to identify a back-off time period for use in transmission of a further RACH preamble.
30. A method according to claim 29, in which said data transmitted to the user terminal comprises data enabling the user terminal to identify said back-off time period from the selected E-A1 of the first type.
31. A method according to claim 30, in which the method fhrthcr comprises maintaining an association between each said E-AI of the first type and a said back-off time period for use in controlling access to said E-DCH.
32. A method according to claim 31, comprising receiving data indicative of said association from a core network entity for use in controlling access to said E-DCH.
33. A method according to claim 29, in which said data transmitted to the user terminal comprises data indicative of a load parameter for use by said user terminal in identification of said back-off time period.
34. A method according to any one of claim 29 to claim 33, the method further comprises: maintaining at least one E-AI of a second type, different to the first type, each said E-Al of the second type being indicative of accessibility of said E-DCH by the user terminal; and in response receiving said further RACH preamble, selecting and transmitting a said E-AI of the first or second type.
35. A method according to claim 34, in which, in the event that the communication network is determined to be capable of accommodating a request associated with the further RACH preamble, the method comprises transmitting a said E-AI of the second type, whereby to cause said user terminal to access said E-DCH.
36. A method of controlling access by a user terminal to a communication network, the user terminal being configured in a CELL_FACH state, the method comprising: receiving data indicative of an extended acquisition indicator (E-AI) of a first type, said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by said user terminal; identifying a back-off time period on the basis of a load condition on the communication network and the received E-AI; and transmitting data indicative of a random access channel (RACH) preamble in response to expiry of said identified back-off time period, whereby to request access to said E-DCH by said user terminal.
37. A method according to claim 36, in which the method comprises detecting the load condition from said received E-AI of the first type.
38. A method according to claim 36 or claim 37, in which said E-Al of the first type is one of a plurality of E-A1I, each said E-AI being associated with a predetermined back-off time period, and the method comprises identifying said back-off time period on the basis of said received E-Al.
39. A method according to claim 38, in which the method comprises receiving and maintaining data indicative of said plurality of E-AIs of the first type and said predetermined back-off time period associated therewith for usc in said identification of the back-off time period.
40. A method according to 36, in which the method comprises receiving data indicative of a load parameter for use in said detection of said load condition on the communication network.
41. A method according to claim 36, in which the method further comprises maintaining a count of said received E-AI of the first type for use in said detection of said load condition on the communication network.
42. A method according to claim 41, in which the method comprises performing said identification of the back-off time period on the basis of said count.
43. A mcthod according to any one of claim 36 to claim 42, in which, responsive to receiving an E-AI of a second type, different to the first type, said E-AI of the second type being indicative of accessibility of said E-DCH by the user terminal, the method ffirthcr comprises transmitting data on said E-DCH in accordance with said received E-AI of the second type.
44. A computer program comprising a set of instructions, which, when executed by a network node, causes the network node to perform a method of controlling access to resources of a communication network by a user terminal, the apparatus comprising a processing system arranged to cause the apparatus to: maintain data to be used in determination of a back-off time period by said user terminal based on load on the communication network, said data comprising at least one extended acquisition indicator (E-AI) of a first type, said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal; and transmit said maintained data for use controlling access to said E-DCH by said user terminal.
45. A computer program comprising a set of instructions, which, when cxccuted by a network nodc, causes the nctwork node to perform a method of controlling access by a user terminal to a communication network, the apparatus comprising a processing system arranged to cause the apparatus to: maintain at least one extended acquisition indicator (E-AI) of a first type, each said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by the user terminal; and in response to receiving a random access channel (RACH) preamble, said RACH preamble being indicative of a request by said user terminal to access said E-DCH, select and transmit data indicative of a said E-AI of the first type, said data transmitted to the user terminal comprising data to be used by the user terminal to idcntifi a back-off time period for usc in transmission of a further RACH preamble
46. A computer program comprising a set of instructions, which, when executed by a network node, causes the network node to perform a method of controlling access by a user terminal to a communication network, the user terminal being configured in a CELL_FACH state, the apparatus comprising a processing system arranged to cause the apparatus to: receive data indicative of an extended acquisition indicator (E-Al) of a first type, said E-AI of the first type being indicative of inaccessibility of an enhanced dedicated channel (E-DCH) by said user terminal; identify a back-off time period on the basis of a load condition on the communication network and the received E-AI; and