WO2010071526A1

WO2010071526A1 - Method and apparatus in a telecommunications network

Info

Publication number: WO2010071526A1
Application number: PCT/SE2008/051529
Authority: WO
Inventors: Gabor Fodor; Magnus Persson; Arne Simonsson; Anders FURUSKÄR; Magnus Frodigh
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2008-12-19
Filing date: 2008-12-19
Publication date: 2010-06-24

Abstract

A mobile terminal (6) transmits a power supply status signal a network node (4) of a telecommunications network (2), indicating whether or not it is connected to an external power supply. The network (2) may then use this information to adapt one or more parameters, or alter the scheduling of resources, etc. For example, if the mobile terminal (6) is connected to an external power supply, the mobile terminal (6) may be scheduled resources, or parameters adapted such that relatively high power consumption takes place in the mobile terminal (i.e. high transmission power is required, or more frequent monitoring of channels, etc). If the mobile terminal (6) is not connected to an external power supply, the mobile terminal may be scheduled resources, or parameters adapted such that relatively low power consumption takes place in the mobile terminal (i.e. low transmission power is required, or less frequent monitoring of channels, etc).

Description

Method and apparatus in a telecommunications network

The present invention relates to methods, mobile terminals and network nodes in a telecommunications network.

Background

The terminal battery is, and is expected to continue to be, a significant bottle neck for long standby time and high data rate transmission in telecommunications systems. Although battery capacities are improving, the terminal form factor mandates smaller batteries, and better displays, power-hungry applications, etc increase power consumption.

Other factors that increase power consumption specifically include high data rates and low latencies. High data rates typically require a higher received energy per information bit than low data rates. Low delays are associated with frequent monitoring of control channels.

An exception to the case when the terminal battery constitutes a bottle neck is when the terminal is connected to an external power supply. In such cases the battery life time is not limiting.

Summary of invention

According to embodiments of the present invention, a mobile terminal transmits a power supply status signal to the network, indicating whether or not it is connected to an external power supply. The network may then use this information to adapt one or more parameters, or alter the scheduling of resources, etc. For example, if the mobile terminal is connected to an external power supply, the mobile terminal may be scheduled resources, or parameters adapted such that relatively high power consumption takes place in the mobile terminal (i.e. high transmission power is required, or more frequent monitoring of channels, etc). If the mobile terminal is not connected to an external power supply, the mobile terminal may be scheduled resources, or parameters adapted such that relatively low power consumption takes place in the mobile terminal (i.e. low transmission power is required, or less frequent monitoring of channels, etc). Thus according to one embodiment of the present invention, there is provided a method in a network node of a telecommunications network, the telecommunications network comprising at least one mobile terminal. The method comprises receiving from the mobile terminal a power supply status signal indicating whether the mobile terminal is connected to an external power source.

According to another embodiment of the present invention, there is provided a network node for use in a telecommunications network, the network node comprising a transceiver and processing circuitry. The transceiver is configured to receive a power supply status signal originating from a mobile terminal, the power supply status signal indicating whether the mobile terminal is connected to an external power source.

According to a further embodiment of the present invention, there is provided a mobile terminal for use in a telecommunications network comprising a network node. The mobile terminal comprises a transmitter and processing circuitry. The processing circuitry is configured to determine whether or not the mobile terminal is connected to an external power source, and to generate a signal a power supply status signal indicating whether the mobile terminal is connected to the external power source. The transmitter is configured to transmit said power supply status signal to said network node.

Brief description of the drawings

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the following drawings, in which:

Figure 1 shows a telecommunications network according to an embodiment of the present invention;

Figure 2 shows a terminal according to an embodiment of the present invention;

Figure 3 shows a radio base station according to an embodiment of the present invention; Figure 4 is a flowchart illustrating a method in a terminal according to an embodiment of the present invention ; and

Figure 5 is a flowchart illustrating a method in a radio base station or radio network control node according to an embodiment of the present invention.

Detailed description

Figure 1 shows part of a telecommunications network 2 according to embodiments of the present invention. The network 2 comprises a radio base station 4, which transmits signals to mobile terminals 6 in downlink communications, and receives signals transmitted by the mobile terminals 6 in uplink communications. The radio base station 4 further communicates with a core network 8. The communication with the core network 8 may be direct (for example as in Release 8 of the 3GPP specifications), or via a radio network controller 9 (for example as in wideband code-division multiple access, WCDMA, or in earlier releases of the 3GPP specifications).

Those skilled in the art will appreciate that numerous devices and features have been omitted from the description of the network 2 for the purposes of clarity. For example, the network 2 will in general comprise a plurality of radio base stations, with each radio base station transmitting to a plurality of mobile stations. The functionality of the radio base station may be divided between several nodes, or performed in a central node controlling several base stations, such as a radio network controller (RNC) 9 in WCDMA or a base station control (BSC) node in GSM (global system for mobile communications). Further, the core network 8 in general comprises a multitude of different devices, which act to control the operation of the network 2, and to pass data, etc from one part of the network to another.

Figure 2 shows a mobile terminal 6 according to embodiments of the present invention. According to the telecommunications standard used by the network 2, the mobile terminal may also be known as a user equipment (UE) or a mobile station.

The mobile terminal comprises an antenna 10 coupled to Tx/Rx circuitry 12. The Tx/Rx circuitry 12 is further coupled to processing circuitry 14. The processing circuitry 14 is coupled to a memory 16, which in general includes random access memory (RAM) and also non-volatile memory. In order to power the mobile terminal 6, the processing circuitry is coupled to power circuitry 18, which acts to distribute power to the mobile terminal 6.

The mobile terminal 6 further comprises a battery 20, for example, a lithium-ion battery, connected to the power circuitry 18. In addition, as is well known in the art, the power circuitry may be selectively coupled to an external power supply 22, such as the mains electricity. This is for example to recharge the battery 20 but, whilst the battery 20 is charging or if the battery is 20 completely charged, the external power supply 22 will also power the mobile terminal 6 directly.

It will be apparent to those skilled in the art that many features generally found in mobile terminals have not been described here for purposes of clarity. Further, alternative arrangements than that illustrated may be employed in the present invention. For example, in order to implement multiple-input multiple-output (MIMO) communications, the mobile terminal may comprise a plurality of antennas, each with its own corresponding Tx/Rx circuitry, or each coupled to common Tx/Rx circuitry.

The mobile terminal 6 may be a phone, or any other device comprising the necessary means for communicating with a telecommunications network, such as a computer, a laptop, a personal digital assistant, etc.

Figure 3 illustrates a radio base station 4 according to embodiments of the present invention. According to the telecommunications standard used in the network 2, the radio base station 4 may also be known as a NodeB or an evolved NodeB (ENodeB).

The radio base station 4 comprises an antenna 30, which is capable of receiving and transmitting signals. The antenna 30 is coupled to transmitter/receiver circuitry 32 (or, more generally, transceiver circuitry), and this is in turn connected to processing circuitry 34.

The radio basestation 4 further comprises core network (CN) interface circuitry 36 for managing one or more interfaces with the core network 8.

It will again be apparent to those skilled in the art that, where they are non-essential for a description of the present invention, numerous features have been omitted from the description of the radio base station 4 for clarity. Moreover, it will also be clear that alternative configurations than that illustrated are possible. For example, in order to implement MIMO communications the radio base station 4 may comprise a plurality of antennas, with each connected to respective Tx/Rx circuitry, or connected to common Tx/Rx circuitry.

According to embodiments of the present invention, the mobile terminal 6 signals to the radio base station 4 whether or not it is connected to the external power supply 22. The radio base station 4 and the core network 8 may then use this information in any of a number of ways, for example to improve the quality of signals transmitted to the mobile terminal 6, as will be described in greater detail below.

Figure 4 is a flowchart illustrating a method in a mobile terminal according to embodiments of the present invention. The method begins in step 40.

In step 42, the processing circuitry 14 of the mobile terminal, in communication with the power circuitry 18, generates a power supply status signal. The power supply status signal comprises an indication of whether or not the mobile terminal 6 is connected to an external power supply 22. According to further embodiments of the present invention, the power supply status signal may further include an indication of the status of the battery 20, such as an amount of energy remaining in the battery 20, a remaining time before the battery runs out, or a remaining percentage of the battery energy. The power supply status signal may further, or alternatively, include an indication of the mobile terminal type, such as: handheld, laptop, fixed wireless or network connected. Such indications can improve the prediction of the power supply lifetime. A fixed wireless terminal is powered from external resources and will never run out of power. A laptop connected to external power supply can be disconnected, limiting the lifetime. When powered by battery a handheld terminal has a much longer lifetime than a laptop.

The power supply status signal may, for example, be a radio resource control (RRC) signal, or a non-access stratum (NAS) signal.

In step 44, the power supply status signal is passed to Tx/Rx circuitry 12 and transmitted using the antenna 10. Figure 5 is a method in a radio base station according to embodiments of the present invention. The method starts in step 50. In step 52, the radio base station receives a power supply status signal from a mobile terminal, indicating whether or not the mobile terminal is connected to an external power supply.

In step 54, the radio base station may perform one or more of several steps according to different embodiments of the invention. That is, the telecommunications network 2 responds appropriately to the power supply status signal. When employed in a telecommunications network as specified by Release 8 of the 3GPP specifications, the radio base station (known as an eNodeB) may determine itself the appropriate action to take — as will be described in greater detail below — and signals this action to the mobile terminal 6 if necessary. In other telecommunications standards, the radio base station 4 may pass the power supply status signal to a radio network controller, or a base station controller, which determines the appropriate action to take, and may instruct the radio base station 4 to signal this to the mobile terminal if necessary.

For example, the radio base station may adapt one or more network parameters based on the received power supply status signal; the radio base station may allocate resources to the mobile terminal according to the received power supply status signal; the radio base station may adapt one or more radio resource control parameters based on the received power supply status signal.

In one embodiment, the mobile terminal is in one of a plurality of possible power states, with state transition rules defining the circumstances in which the mobile terminal moves between power states. For example, the mobile terminal may have a lower power state, where for the majority of the time it is in a "sleep" mode, waking up occasionally to check for paging messages or similar; and also a higher power state, where the mobile terminal is receiving and transmitting data. For example, wideband code-division multiple-access (WCDMA) defines four power states: CELL_PCH, URA_PCH (both low power consumption), CELL_FACH (intermediate power consumption), and CELL_DCH (high power consumption). Similarly, Release 8 of the 3GPP specifications (also known as long term evolution) specifies LTEJDLE (low power consumption) and LTE_ACTIVE (high power consumption).

In one embodiment, the radio base station 4 signals to the mobile terminal 6 to change its power state. For example, if the power supply status signal indicates that the mobile terminal 6 is connected to an external power supply, the radio base station 4 may signal to the mobile terminal 6 to enter a higher power consumption power state (e.g. LTE_ACTIVE, or CELL_DCH). Conversely, if the power supply status signal indicates that the mobile terminal 6 is not connected to an external power supply, the radio base station 4 may signal to the mobile terminal 6 to enter a lower power consumption power state (e.g. LTEJDLE, or CELL_PCH).

In another embodiment, the radio base station 4 signals to the mobile terminal 6 to adapt its rules for transitioning between the power states. For example, a mobile terminal may move from a relatively high power state to a relatively lower power state if it neither transmits nor receives data within a given time period. According to this embodiment, if the mobile terminal is connected to an external power supply, the radio base station may signal the mobile terminal to increase the length of time that must elapse before the mobile terminal transitions to the lower power state.

According to another embodiment, the radio base station 4 may use higher data rates for transmissions to and from the mobile terminal 6 if it is connected to an external power supply. Higher data rates are associated with higher power consumption, but this is not a consideration for a terminal that is plugged into the mains electricity, for example. Higher data rates may be achieved by allocating to the mobile terminal a large amount of resources (i.e. a relatively large range of frequencies and/or timeslots) for transmissions to and from the mobile terminal. For uplink transmissions, higher rates may also be achieved through using relatively higher-order modulation schemes, and relatively higher coding rates (larger transport formats), requiring higher transmission power compared with lower-order modulation schemes and lower coding rates, which require lower transmission power. Conversely, for terminals that are not connected to an external power supply, a relatively small amount of resources may be allocated, such that the terminal saves power.

According to a further embodiment, the radio base station 4 uses resources (i.e. frequencies, timeslots, etc) associated with higher levels of interference for transmissions to and from the mobile terminal 6 if it is connected to an external power supply. Conversely, terminals that are not connected to an external power supply may be allocated resources associated with lower levels of interference. Resources with lower interference require less received power to reach a certain signal quality. Accordingly, mobile terminals may save power when not connected to an external power supply.

According to a yet further embodiment, the radio base station 4 controls the discontinuous reception (DRX) mode of the mobile terminal 6 according to whether or not it is connected to an external power supply. The receiver circuitry in the terminal 6 can be turned off for periods of time in order to save battery resources (known as discontinuous reception (DRX)), i.e. the mobile terminal 6 enters a "sleep" period. According to this embodiment, the radio base station 4 controls the length of time in which the mobile terminal 6 is asleep. This may include controlling which of a plurality of DRX states the mobile terminal 6 is in, each DRX state having a different sleep period, or adapting the length of the sleep period directly, for example. In one embodiment, the mobile terminal 6 may be controlled such that, if it is connected to an external power supply, the sleep periods are shortened compared with the sleep periods of a mobile terminal that is not connected to an external power supply.

According to another embodiment, the radio base station 4 selects the carrier frequency for uplink transmissions according to whether or not the mobile terminal is connected to an external power supply. That is, in this embodiment a plurality of different carrier frequencies are available to the mobile terminal 6 for transmissions to the radio base station 4. The propagation properties can differ significantly between different frequency bands. Typically a signal transmitted at a lower frequency is less attenuated and needs less transmission power from the terminal to achieve a certain received power at the radio base station 4. Thus, in this instance, battery resources are saved when data is transmitted on a relatively lower frequency band. However, it may also be the case that relatively higher-frequency signals are less attenuated that lower-frequency signals, in which case transmitting at the higher frequency saves battery resources. Therefore, in one embodiment, if the mobile terminal 6 is not connected to an external power supply, it may be assigned to a carrier frequency suffering from relatively lower attenuation.

As mentioned above, the radio base station 4 and the mobile terminal 6 may comprise multiple antennas such that MIMO transmissions can take place between them. In one embodiment, the radio base station 4 selects the MIMO transmission rank according to whether or not the mobile terminal is connected to an external power supply. The MIMO transmission rank is the number of transmitted data streams, or parallel code words. In many cases, the higher the transmission rank the less power efficient the transmitted bits are, as there is interference between the different data streams. Therefore, in this embodiment, if the mobile terminal 6 is connected to an external power supply its MIMO transmission rank may be increased relative to the MIMO transmission rank of a mobile terminal that is not connected to an external power supply.

In another embodiment, the radio base station 4 selects multi-user scheduling according to whether or not the mobile terminal 6 is connected to an external power supply. Multiple terminals may be scheduled to transmit to the radio base station 4 on the same resource (i.e. the same frequency and timeslot); this is known as multi-user MIMO, and may be used to increase the capacity in a cell by increasing the number of available radio resources. However, the transmissions on the same resource interfere with each other, and a higher transmission power is required to overcome this problem. Therefore, in this embodiment, the radio base station 4 may not schedule mobile terminals on the same uplink resource if they are not connected to an external power supply.

It will be apparent to those skilled in the art that more than one of the above embodiments may be performed simultaneously. That is, according to whether or not the terminal is connected to an external power supply, the radio base station may adapt the data rates for transmissions to and from the terminal; control the power state of the mobile terminal; adapt the rules for transitioning between power states; allocate the terminal resources with high or low interference; control the DRX mode of the terminal; adapt the scheduled bandwidth of the terminal; select the carrier frequency; select the MIMO transmission rank; and/or select multi-user MIMO scheduling.

In one embodiment, the power supply status signal is user-selectable. That is, the user of the mobile terminal is allowed to disable the transmission of the power supply status signal or to alter its contents. In this way, the mobile terminal may be adapted to indicate that it is connected to an external power supply even if it is not, thus benefiting from increased data rates, etc, at the expense of emptying its battery.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim, "a" or "an" does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims. Any reference signs in the claims shall not be construed so as to limit their scope.

Claims

1. A method in a network node (4) of a telecommunications network (2), the telecommunications network (2) comprising at least one mobile terminal (6), the method comprising: receiving (52) from the mobile terminal (6) a power supply status signal indicating whether the mobile terminal (6) is connected to an external power source.

2. A method as claimed in claim 1 , further comprising: on the basis of whether or not the mobile terminal (6) is connected to an external power source, adapting one or more parameters or operating conditions of the mobile terminal (6).

3. A method as claimed in claim 1 or 2, wherein the power supply status signal further indicates the status of a battery in the mobile terminal (6).

4. A method as claimed in claim 3, wherein the status of the battery includes one or more of: an amount of energy remaining in the battery, a remaining battery time, a percentage of battery capacity remaining and a terminal type.

5. A method as claimed in any one of the preceding claims, wherein the power supply status signal is one of: a radio resource control (RRC) signal; and a non-access stratum (NAS) signal.

6. A method as claimed in any one of the preceding claims, the mobile terminal (6) having a plurality of possible power states, the method further comprising: on the basis of whether or not the mobile terminal (6) is connected to an external power source, controlling which of said plurality of power states the mobile terminal (6) is in.

7. A method as claimed in claim 6, further comprising: on the basis of whether or not the mobile terminal (6) is connected to an external power source, adapting transition rules for said mobile terminal (6) moving between different power states of said plurality of power states.

8. A method as claimed in any one of the preceding claims, further comprising: on the basis of whether or not the mobile terminal (6) is connected to an external power source, adapting data rates of transmissions to and from said mobile terminal (6).

9. A method as claimed in claim 8, wherein said adapting data rates of transmissions from said mobile terminal (6) comprises adapting one or more of: the bandwidth scheduled to said mobile terminal (6) for said transmissions, the modulation scheme for said transmissions, or the coding rate for said transmissions.

10. A method as claimed in any one of the preceding claims, further comprising: on the basis of whether or not the mobile terminal (6) is connected to an external power source, allocating to the mobile terminal (6) resources with relatively high interference, or resources with relatively low interference.

11. A method as claimed in any one of the preceding claims, further comprising: on the basis of whether or not the mobile terminal (6) is connected to an external power source, adapting a period of time in which the mobile terminal (6) is in a sleep mode.

12. A method as claimed in any one of the preceding claims, further comprising: on the basis of whether or not the mobile terminal (6) is connected to an external power source, selecting a carrier frequency for transmissions from the mobile terminal (6) to the network node (4).

13. A method as claimed in any one of the preceding claims, further comprising: on the basis of whether or not the mobile terminal (6) is connected to an external power source, selecting the multiple-input, multiple-output (MIMO) transmission rank for transmissions from the mobile terminal (6) to the network node.

14. A method as claimed in any one of the preceding claims, further comprising: on the basis of whether or not the mobile terminal (6) is connected to an external power source, controlling whether said mobile terminal (6) is scheduled to transmit to the network node on the same resources as other mobile terminals.

15. A network node (4, 9) for use in a telecommunications network (2), the network node comprising processing circuitry (34) and means (30) for receiving a power supply status signal originating from a mobile terminal (6), the power supply status signal indicating whether the mobile terminal (6) is connected to an external power source (22).

16. A network node (4, 9) as claimed in claim 15, the processing circuitry (34) being configured to: on the basis of whether or not the mobile terminal (6) is connected to an external power source, adapt one or more parameters or operating conditions of the mobile terminal (6).

17. A network node (4, 9) as claimed in claim 15 or 16, the mobile terminal (6) having a plurality of possible power states, the processing circuitry (34) being configured to: on the basis of whether or not the mobile terminal (6) is connected to an external power source, control which of said plurality of power states the mobile terminal (6) is in.

18. A network node (4, 9) as claimed in claim 17, the processing circuitry (34) being configured to: on the basis of whether or not the mobile terminal (6) is connected to an external power source, adapt transition rules for said mobile terminal (6) moving between different power states of said plurality of power states.

19. A network node (4, 9) as claimed in any one of claims 15-18, the processing circuitry (34) being configured to: on the basis of whether or not the mobile terminal (6) is connected to an external power source, adapt data rates of transmissions to and from said mobile terminal (6).

20. A network node (4, 9) as claimed in claim 19, wherein the processing circuitry (34) is configured to adapt one or more of: the bandwidth scheduled to said mobile terminal (6) for said transmissions, the modulation scheme for said transmissions, or the coding rate for said transmissions.

21. A network node (4, 9) as claimed in any one of claims 15-20, the processing circuitry (34) being configured to: on the basis of whether or not the mobile terminal (6) is connected to an external power source, allocate to the mobile terminal (6) resources with relatively high interference, or resources with relatively low interference.

22. A network node (4, 9) as claimed in any one of claims 15-21 , the processing circuitry (34) being configured to: on the basis of whether or not the mobile terminal (6) is connected to an external power source, adapt a period of time in which the mobile terminal (6) is in a sleep mode.

23. A network node (4, 9) as claimed in any one of claims 15-22, the processing circuitry (34) being configured to: on the basis of whether or not the mobile terminal (6) is connected to an external power source, select a carrier frequency for transmissions from the mobile terminal (6) to the network node.

24. A network node (4, 9) as claimed in any one of claims 15-23, the processing circuitry (34) being configured to: on the basis of whether or not the mobile terminal (6) is connected to an external power source, select the multiple-input, multiple-output (MIMO) transmission rank for transmissions from the mobile terminal (6) to the network node.

25. A network node (4, 9) as claimed in any one of claims 15-24, the processing circuitry (34) being configured to: on the basis of whether or not the mobile terminal (6) is connected to an external power source, controlling whether said mobile terminal (6) is scheduled to transmit to the network node on the same resources as other mobile terminals.

26. A mobile terminal (6) for use in a telecommunications network (2) comprising a network node (4), the mobile terminal (6) comprising a transmitter and processing circuitry, the processing circuitry being configured to determine whether or not the mobile terminal (6) is connected to an external power source, and to generate a signal a power supply status signal indicating whether the mobile terminal (6) is connected to the external power source, the transmitter being configured to transmit said power supply status signal to said network node (4).

27. A mobile terminal (6) as claimed in claim 26, further comprising a battery, wherein the power supply status signal further indicates the status of said battery.

28. A mobile terminal (6) as claimed in claim 27, wherein the status of the battery includes one or more of: an amount of energy remaining in the battery, a remaining battery time, a percentage of battery capacity remaining and a terminal type.

29. A mobile terminal (6) as claimed in any one of claims 26-28, wherein the power supply status signal is one of: a radio resource control (RRC) signal and a non-access stratum (NAS) signal.

30. A mobile terminal (6) as claimed in any one of claims 26-29, wherein said power supply status signal is user-selectable.