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EP-4324282-B1 - METHOD AND NETWORK NODE OF WIRELESS COMMUNICATION NETWORK FOR HANDLING RANDOM ACCESS

EP4324282B1EP 4324282 B1EP4324282 B1EP 4324282B1EP-4324282-B1

Inventors

  • Hou, Xueying
  • XU, BO
  • FRENGER, Pål

Dates

Publication Date
20260506
Application Date
20210413

Claims (14)

  1. A method performed by a network node (130) of a wireless communication network (100), the network node (130) having a plurality of receivers (131, 132, 133), the method comprising: receiving (206), from a wireless device (140), a random access preamble when a first number of the plurality of receivers are active and a second number of the plurality of receivers are inactive; sending (208), to the wireless device (140), a random access response, in response to the received random access preamble; determining (212) whether a reception requirement for a subsequent random access procedure message sent by the wireless device towards the network node is fulfilled, the subsequent random access procedure message being sent by the wireless device subsequent to the network node sending (208) the random access response, the reception requirement being either whether the subsequent random access procedure message is received at the network node or whether the subsequent random access procedure message that is received has a sufficient quality, and when the reception requirement is determined not fulfilled, activating (214) at least some of the inactive second number of receivers.
  2. Method according to claim 1, further comprising: broadcasting (204), before the receiving (206) of the random access preamble from the wireless device (140) and in connection with inactivation of the second number of receivers, a configuration message for configuration of the random access preamble, the configuration message including a second configuration of the random access preamble that is more robust than a first configuration of the random access preamble that is broadcasted when no receivers or fewer receivers than the second number of receivers are inactivated, and wherein the random access preamble that is received (206) is of the second configuration.
  3. Method according to claim 2, wherein the second configuration is more robust than the first configuration in that a sequence is configured for the random access preamble that is longer in time in the second configuration than in the first configuration.
  4. Method according to claim 2 or 3, wherein the second configuration of the broadcasted (204) configuration message includes a shortened random access preamble periodicity compared to the first configuration.
  5. Method according to any of the preceding claims, further comprising: inactivating (202), before the receiving (206) of the random access preamble, the second number of the plurality of receivers, based on one or more of: number of wireless devices connected to the network node; signal quality such as signal strength of wireless devices connected to the network node; network node backup battery level; network node temperature; cost of network node power; distortion of one or more of the plurality of receivers, and data traffic load between the network node and wireless devices connected to the network node.
  6. Method according to any of the preceding claims, wherein the sent (208) random access response comprises information on the subsequent random access procedure message, the information indicating to the wireless device to use more communication resources, a higher transmit power and/or a more robust coding for the subsequent random access procedure message compared to when the second number of receivers are active.
  7. Method according to any of the preceding claims, further comprising: receiving (210) the subsequent random access procedure message sent by the wireless device in response to the sent random access response, and wherein the reception requirement is whether the subsequent random access procedure message received has a sufficient quality, and wherein the reception requirement is determined (212) not fulfilled when a signal quality of the subsequent random access procedure message is below a threshold.
  8. Method according to claim 7, further comprising, when the signal quality of the received (210) subsequent random access procedure message is determined to be below the threshold and at least some of the inactive second number of receivers have been activated, sending (216), towards the wireless device (140), a random access message subsequent to the subsequent random access procedure message.
  9. Method according to any of the preceding claims, wherein the activating (214) of at least some of the second number of receivers further triggers configuring a preamble received target power value and broadcasting the configured preamble received target power value in the cell in which the wireless device resides.
  10. Method according to any of the preceding claims, wherein the reception requirement is whether the subsequent random access procedure message is received, and wherein the reception requirement is determined (212) not fulfilled when the subsequent random access procedure message has not been received within a running time of a timer T started when the random access response was sent (208).
  11. Method according to any of the preceding claims, further comprising, when the reception requirement is determined (212) fulfilled: sending (216), towards the wireless device (140), a random access message subsequent to the subsequent random access procedure message.
  12. A network node (130) configured to operate in a wireless communication network (100), the network node (130) having a plurality of receivers (131, 132, 133), the network node (130) comprising a processing circuitry (603) and a memory (604), said memory containing instructions executable by said processing circuitry, whereby the network node (130) is operative for performing the method of any of the claims 1-11.
  13. A computer program (605) comprising instructions, which, when executed by at least one processing circuitry of a network node (130) of a wireless communication network, the network node (130) having a plurality of receivers (131, 132, 133), causes the network node (130) to perform the following steps: receiving, from a wireless device (140), a random access preamble when a first number of the plurality of receivers are active and a second number of the plurality of receivers are inactive; sending, to the wireless device (140), a random access response, in response to the received random access preamble; determining whether a reception requirement for a subsequent random access procedure message sent by the wireless device towards the network node is fulfilled, the subsequent random access procedure message being sent by the wireless device subsequent to the network node sending (208) the random access response, the reception requirement being either whether the subsequent random access procedure message is received at the network node or whether the subsequent random access procedure message that is received has a sufficient quality, and, when the reception requirement is determined not fulfilled, activating at least some of the inactive second number of receivers.
  14. A carrier containing the computer program (605) according to claim 13, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, an electric signal or a computer readable storage medium.

Description

Technical Field The present disclosure relates generally to a method and a network node for handling random access in a wireless communication network. More specifically, the disclosure relates to a method and a network node for handling or controlling random access of wireless devices to a wireless communication network. The present disclosure further relates to a computer program and a carrier of said computer program corresponding to the above mentioned method and network node. Background In wireless communication networks, such as 5th Generation (5G) networks, e.g., New Radio (NR), power consumption is a big issue for network operators. For a network node, e.g., base station equipped with many transmitters (TX) and receivers (RX), one way to achieve better energy efficiency and reduce operational cost for this kind of network node is to switch off some antenna branches by inactivating TXs and/or RXs connected to these antenna branches, for example when data traffic between wireless devices and the network node is low. This may be called that the network node is in muting mode. Exmples of the prior art are: US 2021/051710 A1 (Cirik Ali [US] et al) 18 February 2021; and US 2020/350972 A1 (Yi Yunjung [US] et al) 5 November 2020. On the receiver part of the network node, inactivating some RXs to save power will cause reduction in uplink (UL) link budget and radio coverage. When a wireless device is in good channel conditions, e.g., close to the network node or in Line-Of-Sight (LOS), such reduction in UL link budget may not cause problems in communication quality between the wireless device and the network node. However, when the wireless device is in bad channel conditions, e.g., at the edge of the cell in which the network node provides coverage or in Non-LOS (NLOS), such reduction may cause communication failure in UL. In downlink (DL), this can be partly mitigated by the network node sending a power boosted Synchronization Signal Block (SSB) to preserve the DL broadcast coverage when some TXs are muted. However, for the UL, the received signal strength at the network node will be reduced when some RXs are inactivated, which will risk that signals from wireless devices cannot be received correctly at the network node. A situation when this problem may appear is in the random access procedure. For example, a wireless device trying to perform random access when some RXs of the network node are inactivated may not be able to do that even though the wireless device is within the cell of the network node. Consequently, there is a need for an improved random access procedure that mitigates such a problem. Summary It is an object of the invention to address at least some of the problems and issues outlined above. The scope and objectives of the present invention is defined in the appended independent claims. Specific embodiments of the present invention are defined in the dependent claims. In the followings some parts of the description, that are not covered by the claims, are considered background information that is useful for understanding the present invention. According to claim 1, a method is provided that is performed by a network node of a wireless communication network, the network node having a plurality of receivers. The method comprises receiving, from a wireless device, a random access preamble when a first number of the plurality of receivers are active and a second number of the plurality of receivers are inactive, and sending, to the wireless device, a random access response, in response to the received random access preamble. The method further comprises determining whether a reception requirement for a subsequent random access procedure message sent by the wireless device towards the network node is fulfilled, the subsequent random access procedure message being sent by the wireless device subsequent to the network node sending the random access response. The reception requirement is either whether the subsequent random access procedure message is received at the network node or whether the subsequent random access procedure message that is received has a sufficient quality. The method further comprises, when the reception requirement is determined not fulfilled, activating at least some of the inactive second number of receivers. According to independent claim 12, a network node is provided that is configured to operate in a wireless communication network. The network node has a plurality of receivers. The network node comprises a processing circuitry and a memory. Said memory contains instructions executable by said processing circuitry, whereby the network node is operative for receiving, from a wireless device, a random access preamble when a first number of the plurality of receivers are active and a second number of the plurality of receivers are inactive, and sending, to the wireless device, a random access response, in response to the received random access preamble. The network node i