WO2018033197A1

WO2018033197A1 - Dynamic priority setting to improve peak rates in a wireless communication network

Info

Publication number: WO2018033197A1
Application number: PCT/EP2016/069348
Authority: WO
Inventors: Anders Ericsson
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2016-08-15
Filing date: 2016-08-15
Publication date: 2018-02-22
Anticipated expiration: 2019-02-15

Abstract

Disclosed herein is a method for improving performance of a communication network. The method comprises performing a carrier sensing operation in a communication channel in order to determine whether a transmission activity is occurring in the communication channel and transmitting data intended for transmission in the communication channel during a channel occupation time if it is determined that no transmission activity is occurring in the communication channel. The method also comprises determining, when the channel occupation time has expired, whether all of the data intended for transmission has been transmitted. If such is not the case the method also comprises determining a level of interference in the communication channel. If the level of interference is determined to be below an interference threshold the method also comprises checking a first priority level of data that has not been transmitted and setting a second priority level of the data that has not been transmitted based on the first priority level. Also disclosed is computer program product, an arrangement, a network node and a wireless communication device.

Description

DYNAMIC PRIORITY SETTING TO IMPROVE PEAK RATES IN A WIRELESS COMMUNICATION NETWORK

Technical Field

The present invention relates generally to the field of wireless communication.

More particularly, it relates to dynamic priority settings to improve peak rates in wireless networks.

Background

License Assisted Access, LAA, is currently being standardized and is a way to use unlicensed spectrum for offloading or increasing capacity of, for example, Long Term Evolution (LTE) systems such as Universal Mobile Telecommunication Systems (UMTS) LTE advocated by the 3GPP. As these unlicensed spectra are typically used by various technologies (e.g. WiFi), some kind of sensing is needed by transmitters before they start transmitting in order to avoid collisions with other units who may also use the spectrum. In LAA, a Listen Before Talk, LBT scheme, similar to that used by WiFi is proposed to ensure coexistence within LAA networks but also with other technologies.

Without loss of generality, in this disclosure, use of LAA as implemented in 3GPP release 13 may be taken as an example. However, the described principles can be used in other variants of systems using unlicensed spectrum utilizing some kind of Carrier Sensing, CS, as mechanism to enable coexistence.

Any transmission by an LAA transmitter is preceded by a sensing period. Furthermore, a maximum channel occupancy time, MCOT, is stipulated, during which transmission may take place and after which a new sensing of the communication channel is needed.

The LBT procedure typically starts with a deferral time period, after which a certain number of successful Clear Channel Assessments, CCA, shall be carried out.

When transmission is granted, i.e. when a certain number of successful CCA has been obtained, a normal LTE scheme is used for communication. As a consequence, part of the time available is consumed by the LBT procedure, regardless of whether the channel is occupied or not. The length of the LBT procedure typically depends on a priority class which the data to be transmitted has, and the load of the system, i.e. the likelihood that other transmitters occupy the same channel. Hence, even if a transmitter is alone in a channel there is some overhead since a new LBT procedure needs to be performed after MCOT is reached. This overhead may give rise to an unnecessary delay in the network which may impact communication efficiency.

Therefore there is a need for methods and arrangements for improving network performance, such as reducing delay and increasing overall throughput when e.g. LAA is to be utilized. Summary

It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

It is an object of some embodiments to mitigate at least some of the above disadvantages and to provide methods, arrangements, computer program products, network nodes and wireless communication devices for enabling improved network performance.

According to a first aspect this is achieved by a method for improving performance of a communication network.

The method comprises performing a carrier sensing operation in a

communication channel in order to determine whether a transmission activity is occurring in the communication channel and transmitting data intended for transmission in the communication channel during a channel occupation time if it is determined that no transmission activity is occurring in the communication channel.

The method also comprises determining, when the channel occupation time has expired, whether all of the data intended for transmission has been transmitted. If not, the method further comprises determining a level of interference in the communication channel.

If the level of interference is determined to be below an interference threshold the method comprises checking a first priority level of data that has not been transmitted and setting a second priority level of the data that has not been transmitted based on the first priority level.

Network performance may e.g. comprise such parameters as overall throughput, signal quality, network delay, transmission peak rates, success rates of transmitted packages, etc.

When applying LAA and Listen Before Talk (LBT) the transmission peak rate is an indication of how much data that is transmitted during a maximum channel occupancy time (MCOT). The MCOT defines for how long a transmitter may occupy the channel in order to transmit its data.

In some embodiments, the priority level is indicative of a length the channel occupation time, such that the length of the channel occupation time is increased if the priority level is decreased and decreased if the priority level is increased.

In some embodiments, the relation may be the opposite, i.e. the length of the channel occupation time is shortened if the priority level is increased and vice versa.

The MCOT may at least partially be based on a level of priority which is assigned to the data that is to be transmitted. In general, a high priority level of the data results in an aggressive LBT procedure which ideally grants quick access to the communication channel but also defines a short MCOT, whereas data having a low priority level may have to wait for longer periods of time before being granted access to be transmitted. In return the MCOT is set to be longer resulting in that the likelihood that all the low priority data which is scheduled for transmission is transmitted during one MCOT is higher.

According to LAA as defined in 3 GPP version 13, the priority level or priority class is set to be between 1 and 4, where 1 is the highest priority and 4 is the lowest.

However other ways of defining the priority is of course imaginable. For instance, other integers such as e.g. 1-10, 1-100, 20-50, or letters, or code

representations, or other suitable representations may be used to denote priority.

For simplicity, the priority levels 1-4 as defined by LAA will be used as an example in this disclosure.

Data having priority 1 or 2 is likely to be given quick access to the

communication channel for transmission. However, if the amount of data is large, there is a risk that not all of it will be transmitted during the MCOT associated with the high priority. Thus, the LBT procedure will have to be carried out one or more times for the same batch of high priority data. Even if the channel interference is low, and the LBT is immediately successful, the overall transmission time may become quite long if a lot of data is to be sent.

In some embodiments, the second priority level is set to the first priority level if it is determined that the level of interference is above the interference threshold.

For instance, if the level of interference of the channel is high, it may be beneficial to keep the original priority level since it may be crucial that data having a high priority quickly gains access and is transmitted, especially when interference is high, whereas there will be no harm in letting low priority data wait.

In some embodiments, the method may further comprise transmitting the data that has not been transmitted with the second priority level and reverting to the first priority level if interference is detected in the communication channel during the data transmission.

For instance, if the priority level is changed to a lower priority level (e.g. from 1 or 2 to 3) because it is determined that there still is data to send and there is little or no interference in the channel. LBT is carried out again for the remaining data, which now has another lower priority level. If the LBT is successful transmission with a longer MCOT may begin.

However, since the priority level has been changed the channel should be monitored during transmission such that the transmission may be aborted, and the second priority level be changed back to the first priority level if a transmission collision in the channel is detected.

This procedure may ensure that the channel is not blocked by data that should not be allowed to block the channel (i.e. data that is originally assigned a shorter MCOT).

The reversion to the first (original) priority level may in some embodiments be immediate, i.e. the transmission is instantly aborted and the second priority level is changed back to the first (original) priority level. In some embodiments, if a collision is detected, it may be determined if a time corresponding to the MCOT of the first priority level has expired, and if so abort transmission, and if not, continue transmission until the MCOT corresponding to the first priority level has expired.

In some embodiments, the method may further comprise storing each determined interference level in a memory. Determining the level of interference may further comprise computing an estimated interference level based on the stored determined interference level.

If the various interference values are stored, then a history of interference may be constructed which may provide statistics and function as input when determining the level of interference for a coming transmission, i.e. an expected or estimated value of the level of interference.

In some embodiments, the level of interference may be based on at least one of a number of transmission collisions in the communication channel, a number of unsuccessful carrier sensing operations, a power of interference from an adjacent communication channel, and detected interference in the network.

The number of unsuccessful carrier sensing operations may e.g. denote how often a collision was detected during the LBT procedure, i.e. how many CCAs that were unsuccessful before transmission was allowed.

In some embodiments, the number of unsuccessful carrier sensing operation may denote the number of non-successful transmissions, i.e. how often reports pertaining to that data which was transmitted during MCOT was not decoded correctly.

In some embodiments the number of unsuccessful carrier sensing operations may e.g. denote how many collisions were detected during the LBT procedure

In some embodiments, the level of interference may also be based on the length of a deferral time period associated with the LBT procedure, i.e. the random length of the time which a network node or wireless communication device waits prior to performing the clear channel assessments.

In some embodiments, the level of interference may be based on a number NACKs (No Acknowledgement message) received during a previous MCOT. The NACKs may indicate how much of the transmission that was successful. In some embodiments, the carrier sensing operation is a listen before talk - LBT - operation.

In some embodiments, the method is performed in downlink and/or in uplink. In some embodiments, the communication network utilizes License Assisted Access - LAA.

In some embodiments the communication network is a long term evolution - LTE - network.

In some embodiments, the method is carried out in an unlicensed spectrum. Unlicensed spectrum may e.g. be utilized by WiFi networks, and may further comprise Industrial Scientific and Medical ISM bands or the like.

A second aspect is a computer program product comprising a computer readable medium, having thereon a computer program comprising program instructions.

The computer program is loadable into a data-processing unit comprising a memory and a processor and adapted to cause execution of the method according to the first aspect when the computer program is run by the data-processing unit.

The computer program product may be a non transitory computer program product.

A third aspect is an arrangement of a communication device configured to operate in a communication network for improving performance of the communication network. The arrangement comprises a transceiver and a controller.

The controller is configured to cause performance of a carrier sensing operation in a communication channel in order to determine whether a transmission activity is occurring in the communication channel and transmission of data intended for transmission in the communication channel during a channel occupation time if it is determined that no transmission activity is occurring in the communication channel.

The controller is also configured to cause determination of, when the channel occupation time has expired, whether all of the data intended for transmission has been transmitted.

If such is not the case, the controller is further configured to cause

determination of a level of interference in the communication channel. If the level of interference is determined to be below an interference threshold, the controller is configured to cause checking of a first priority level of data that has not been transmitted and setting of a second priority level of the data that has not been transmitted based on the first priority level.

The controller may further comprise a priority unit, a determiner, an interference unit and a carrier sensing organ.

The controller may be configured to cause the carrier sensing organ to perform the carrier sensing operation in order to determine whether a transmission activity is occurring in the communication channel.

The controller may also be configured to cause the transceiver to start transmission of data intended for transmission in the communication channel during the channel occupation time if it is determined that no transmission activity is occurring in the communication channel.

The controller may then cause the determiner to determine, when the channel occupation time has expired, whether all of the data intended for transmission has been transmitted.

If not all data intended for transmission has been transmitted, the controller may further be configured to cause the interference unit to determine a level of interference in the communication channel.

If the interference unit determines the level to be below the interference threshold, the controller may be configured to cause the priority unit to check the first priority level of the data that has not been transmitted and set the second priority level of the data that has not been transmitted based on the first priority level.

The controller may further be configured to cause the priority unit to set the second priority level to the first priority level if it is determined (e.g. by the interference unit) that the level of interference is above the interference threshold.

The controller may further be configured to cause the transceiver to transmit the data that has not been transmitted but with the second priority level set instead of the first. During transmission the controller may cause the carrier sensing organ to monitor the channel and communicate to the controller if a transmission collision is detected in the channel.

In some embodiments, the transmission may be immediately aborted, or if a time corresponding to the MCOT associated with the original priority level has not yet expired, the transmission may continue until this time has expired and then be aborted.

Immediate may in some embodiments mean as soon as possible.

Furthermore, in some embodiments, the priority level is indicative of a length the channel occupation time, such that the length of the channel occupation time is increased if the priority level is decreased and decreased if the priority level is increased.

In some embodiments the controller is configured to cause setting of the second priority level to the first priority level if it is determined that the level of interference is above the interference threshold.

In some embodiments, the controller is further configured to cause

transmission of the data with the second priority level that has not been transmitted and cause reversion to the first priority level if interference is detected in the communication channel during the data transmission.

In some embodiments, the controller is further configured to cause storage of each determined interference level in a memory and determining the level of interference comprises computation of an estimated interference level based on the stored determined interference level.

In some embodiments, the interference level is based on at least one of a number of transmission collisions in the communication channel, a number of unsuccessful carrier sensing operations, a power of interference from an adjacent communication channel, and detected interference in the network.

A fourth aspect is a network node comprising the arrangement according to the third aspect.

A fifth aspect is a mobile terminal comprising the arrangement according to the third aspect. In some embodiments, the third, fourth and fifth aspects may additionally have features identical with or corresponding to any of the various features as explained above for the first aspect.

An advantage of some embodiments is that overall peak transmission rates and thus overall throughput in a communication network is increased.

Another advantage of some embodiments is that priority levels may be dynamically set in order to increase network efficiency while still ensuring that the channel is not occupied such that scheduled data is obstructed from transmission. Brief Description of the Drawings

Further objects, features and advantages will appear from the following detailed description of embodiments, with reference being made to the accompanying drawings, in which:

Fig. 1 is a schematic drawing illustrating a carrier sensing mechanism;

Fig. 2 is a table illustrating example parameters of a carrier sensing

mechanism;

Fig. 3 is a table illustrating example parameters of a carrier sensing

mechanism;

Fig. 4 is a flow chart illustrating example method steps according to some embodiments;

Fig. 5 is a flow chart illustrating example method steps according to some embodiments;

Fig. 6 is a schematic drawing of an arrangement according to some

embodiments; and

Fig. 7 is a schematic drawing of a computer program product according to some embodiments.

Detailed Description

In the following, embodiments will be described where network performance is enhanced by means of dynamically setting of a priority level of data that is to be transmitted in a communication channel based on the experienced channel interference as well as the original priority level of the data that is to transmitted.

For simplicity, a License Assisted Access (LAA) network according to the 3 GPP standard version 13 is assumed. However, this is merely meant as an example and is by no means to be considered limiting. On the contrary, embodiments may be equally applicable to any wireless communication system where a sensing period is applied before transmission.

In the LAA network Listen Before Talk (LBT) is employed in order to assess whether a communication channel is empty or occupied.

For instance, a network node, such as a base station or evolved node B (eNB) when wishing to transmit in downlink (or receive in uplink) to a wireless

communication device may first determine if the communication channel is available by carrying out some kind of carrier sensing mechanism or operation such as e.g. Carrier Sense Multiple Access (CSMA), Carrier Sense Multiple Access Collision Avoidance (CSMACA) or Listen Before Talk (LBT).

A typical carrier sensing operation is the LBT procedure as illustrated by Fig. 1. For example, in Fig. 1 a network node may whish to transmit data to a wireless communication device.

Assume in Fig. 1 that a data transmission is ongoing during a maximum channel occupation time (MCOT) 101a. During this time, data is transmitted. When the MCOT 101a expires no more data may be transmitted again until the network node has performed a channel assessment according to LBT.

In 102a the node defers from transmitting but only listens to the channel. During the deferral period 102a Clear Channel Assessment (CCA) is performed using energy detection. The deferral period 102a ends when the channel has been clear during a stipulated time td (i.e. no collisions have been detected) , where td depends on the priority class. Then CCA measurements are performed during 9 and a number N of these CCA measurements has to be successful in order to allow for transmission.

N is initialized to a random number. As an example, in Fig. 1, N is set to be 3.

In 103a, N= 3 and a CCA is performed. If traffic is detected in 103a, i.e. the CCA results in a detected collision (as indicated by "x" in 103a), then N is kept to 3. Since a collision was detected, the system waits for yet another deferral period 102b which lasts until the channel has been clear for a stipulated time td before a new CCA is performed in 103b.

The CCA performed in 103b is successful (no collision was detected), resulting in that N is decreased by one, i.e. set to 2 and a new CCA is performed in 103c.

The CCA performed in 103c is not successful, i.e. a collision was detected, and another deferral period 102c is carried out before the next CCA 103d, where N is kept to 2.

CCA in 103d is successful, N is decreased to 1 and yet another CCA is performed in 103e. As the CCA in 103e is also successful, N is set to zero and transmission of the data that was not sent during the first MCOT 101a may start during the second MCOT in 101b.

When MCOT 101b has expired a new deferral period 102d starts prior to new CCA events.

The random number N may be increased if collisions are detected in order to elongate the waiting time and increase the probability that the channel will be vacant during the transmission.

It should be noted that the procedure and described in Fig. 1 is exemplary and that it may look different for different scenarios. For instance, the number of deferral periods and CCAs may vary.

When transmission is granted, a normal LTE scheme, i.e. following LTE physical Layer scheduling principles is used. As a consequence, part of the time available for transmission is consumed by the LBT procedure. The length of the LBT procedure depends at least in part on a priority class which the data to be transmitted has, and the load of the system, i.e. the likelihood that other transmitters occupy the same channel.

For example, a low priority level such as 3 or 4 may have a larger initial random number for N, such as 5 or 10, the deferral period may be longer, and the MCOT is longer, whereas a high priority level, such as 1 or 2, may have a smaller initial random number for N such 1-4, a shorter deferral period and a shorter MCOT. Hence, even if a transmitter is alone in sending on a channel there is some overhead, since it needs to do a new LBT after MCOT has expired if not all of the intended data was transmitted.

If there is no interference, expected average fraction of time spent transmitting can be calculated depending on the priority level using, e.g. the parameters illustrated in the table 200 of Fig. 2.

In Fig. 2, the following parameters are defined:

CWmin is the minimum Contention Window, the contention window defines duration of a random back off which is performed if a collision is detected, i.e. how long the node will wait before trying to perform a new CCA when the previous CCA resulted in a collision.

n is defining the deferral period that starts each LBT procedure.

MCOT is the maximum channel occupancy time.

Since 8 ms is the typical value for MCOT for lower priorities it has been used as an example in Fig. 2. However, there are exceptions in some regions and it can also be extended to 10ms under certain conditions.

The deferral period, td, is according to the 3GPP LTE Rel 13 LAA. 36.213 given by

The time spent in "contention", t_c, is given by

where N is a random number as described in conjunction with Figure 1 , and NCCA is the number of negative Clear Channel Assessments, CCA, during an LBT procedure.

N is furthermore an integer drawn from a uniform distribution [0, CW] where CW is the Contention Window. CW is initialized to CWmin and is doubled when previous transmission has a number of transport blocks with NACKs (negative acknowledgements) above a certain threshold. The maximum length of CW is limited to CW = CWmax. If previous transmission has a number of NACKs below a threshold, CW is reset to CWmin.

Hence, in an interference free case,

CW = CWmin and NCCA =0. The expected value of N is thus:

E(N) = E(CW)/2 = CWmin/2. Thus, the average time spent in LBT, tLBT, in an interference free case is E(t_LBT)= t_d + E(tc) = t_d + E(N) = 16 + ( n + CW_mi„/2) * 9 μ&.

When the LBT period is finished, the transmission can start. However, since LTE is time synchronized it can only start at an OFDM symbol. Furthermore, an LAA transmission is stipulated to start at symbols 0 or 7 resulting in an average delay, t_r, of 3.5 symbols (0.25 ms) before the actual transmission starts. This time is part of the overhead, and if reservations signals are used to avoid that another user starts to transmit, it is included in MCOT.

Thus the efficiency ratio or transmission peak rate, γ, between the efficient transmit time, t_e, and the total time, ttot, may be calculated as = te / ttot = t_e / (E(tLB_T) + MCOT) = (MCOT- t_r) / (16 + ( n + CWmin/2) * 9 μ8 +

MCOT) as seen in the table 300 of Fig. 3 where the values of table 200 of Fig. 2 are applied.

Fig. 3 shows that the efficiency at peak rate scenarios is worse for the highest priority classes (lowest numbers, i.e. 1, 2) than for the lowest (higher numbers, i.e. 3, 4). This is mainly due to trade-off done with getting quick access to the medium (short td and t_c) versus long MCOT.

Thus, if there is low interference in the communication channel it could be beneficial if data which is set with a high priority were to take advantage of the longer MCOT which is provided for data with lower priority.

An example method according to this is illustrated in Fig. 4.

The method 400 of fig 4 may be a method for improving performance of a communication network. The method 400 starts in 401 where a transmission is initiated. However, as elaborated on above, a carrier sensing operation such as LBT should be carried out prior to transmitting anything in a communication channel in order to make sure that the channel is vacant.

In 402 of the method 400 a carrier sensing operation is performed in the communication channel in order to determine whether a transmission activity is occurring in the communication channel.

The carrier sensing operation may be a LBT procedure as described in conjunction with any of the Figs. 1-3, or it may be any other suitable carrier sensing technique such as SCMA or similar.

In 403 the method 400 continues with transmitting data intended for transmission in the communication channel during a channel occupation time if it is determined that no transmission activity is occurring in the communication channel

(compare with Fig. 1). For instance, it may be determined that no transmission activity is occurring in the communication channel if the LBT procedure resulted in N number of positive CCA.

Data to be transmitted may be stored in a buffer, from which it is retrieved when MCOT starts.

The method 400 continues with determining in 404, when the channel occupation time has expired, whether all of the data intended for transmission has been transmitted. It may e.g. be determined whether there still is data to be transmitted left in the buffer. If not (N-path out of 404), then the buffer is empty and all data that was intended to be transmitted has been transmitted and in 405 of the method 400 transmission is ended.

However, if there is data left in the buffer, (Y-path out of 404) the method continues in 406 where a level of interference is determined in the communication channel.

If in 407 the level of interference is determined to be below an interference threshold (Y-path out of 407) the method may continue with checking a first priority level of the data that has not been transmitted (not shown in Fig. 4 as this step in some embodiments may be left out), and in 409 set a second priority level of the data that has not been transmitted based on the first priority level. For instance, if the first priority level is 1 and the interference is determined be below the interference threshold, the priority level may be set to 3.

If in 407 it is determined that the interference level is not below the

interference threshold (N-path out of 407) the priority level is in 408 set to the first priority level i.e. second priority level is set to the first priority level if it is determined that the level of interference is above the interference threshold. For instance, if the first priority level is 1 , and the interference is determined to be above the interference threshold, the priority level may be set to 1, i.e. remain unchanged.

In some embodiments, if the first priority level is determined to be 3 or 4, the method may comprise not changing the priority level regardless of the level of interference. For instance, as seen in table 300 of Fig. 3 the transmission peak rate is high for both priority level 3 and 4. If the level of interference is low, there is thus no need to change a low priority level to a high priority level as this would negatively affect the transmission peak rate. If the level of interference is high, data having low priority should not be upgraded to higher priority since it is more important that data which is designated as high priority data is transmitted before low priority data is.

The method 400 may in some embodiments be carried out by a network node, such as a base station or an eNB. The method is preferably performed in downlink but it is also possible that the method is performed in uplink, e.g. by a wireless

communication device such as a mobile phone or other wireless device. In some embodiments, the priority level is indicative of a length of the channel occupation time, such that the length of the channel occupation time is increased if the priority level is decreased and vice versa.

Thus when the method 400 is applied, data having a high priority may be given a lower priority if there is little or low interference in the communication channel, resulting in that the transmission time for the data is elongated. This in turn results in that the transmission peak rate is increased (compare with Fig. 3) and the network performance may be improved in terms of transmission time, less congestion and delay, network flow etc.

In Fig. 5 an example method 500 according to some embodiments is illustrated.

The method 500 may in some embodiments be combined with the method 400 described in conjunction with Fig. 4.

The method 500 may start in 501 where a transmission is initiated. Since no transmission may take place before it has been determined that the communication channel is empty, a carrier sensing operation is carried out in 502. The carrier sensing operation may e.g. be a LBT procedure such as described in any of the Figs. 1-4.

In 503 if a collision is detected (Y-path out of 503) e.g. if CCA is unsuccessful, then that is an indication that the channel is occupied and significant interference is present. The method may then continue in 504 where a priority level of the data that is to be transmitted is set to its original or default priority level. That is, the priority level which the data was designated with from the beginning by for example the network node.

If collisions are detected it may be crucial that high priority data gets to keep its high priority so that it is ensured that it's transmitted as soon as possible even if it means that it may only be transmitted in part. In the same manner, there is no risk in letting low priority data queue for a longer period of time if the channel is already occupied.

The method may then continue in 505 where the data is transmitted.

However, if in 503 no collision is detected (N-path out of 503) the method may also continue in 505 with transmitting data during a time period corresponding to the maximum channel occupation time (MCOT) associated to the current priority level of the data (compare with step 403 of the method 400).

When MCOT has expired the method continues in 506 where it is checked whether there still is data to be transmitted left in the buffer.

If there is no data left in the buffer (N-path out of 506) then the method continues in 507 where the transmission is ended.

If there is data left in the buffer (Y-path out of 506), then the method continues in 508 where it checks if the level of priority is of high priority or of low priority.

If it is assumed that the method 500 is carried out by a network node in a LAA network according to 3 GPP version 13, then high priority may be seen as priority levels 1 and 2 whereas low priority are priority levels 3 and 4 (compare with tables 200 and 300 in Figs. 2 and 3). However, the method is applicable on other types of systems and is not limited to the priority levels 1-4. Furthermore, the expression high and low priorities are relative expression that may have different meaning depending on the system or application for which they are used.

A skilled person would undoubtedly be able to recognize this and adapt the method suitably for different implementations even if they are not explicitly described here.

If in 508 it is determined that the priority level is set to 3 or 4 (N-path out of 508) which may be regarded as a low priority having rather high transmission peak rate then there may exist no reason to change the priority level, regardless of how much interference that is present in the communication channel, since the transmission peak rate is already high (compare with table 200 in Fig. 2) the priority level may then be kept unchanged and the method continues in 502 where the carriers sensing operation is carried out again.

It should be noted that the step 508 may look different if other levels of priority are used. The step may also be omitted.

In some embodiments it may also be that a low priority is changed to a high priority, i.e. if the first priority level is 3 or 4, the second priority level may be set to 1 or 2. This may depend on different factors pertaining to the network. In future systems it may e.g. be that a higher priority level results in a better transmission peak rate than a lower.

If in 508 it is determined that the priority level is set to 1 or 2 (Y-path out of 508), the method may continue in 509 where the interference level of the

communication channel is determined (or at least estimated) (compare with step 406 of the method 400).

In order to determine the level of interference, each previously determined or estimated interference level may be stored in a memory. Determining the level of interference may thus comprise computing an estimated interference level based on each stored determined interference level.

The level of interference may e.g. be based on at least one of a number of transmission collisions in the communication channel, a number of unsuccessful carrier sensing operations, a power of interference from an adjacent communication channel, and detected interference in the network.

Collisions may in this disclosure be seen as the number of actual transmission collisions (e.g. collisions that occurs during data transmission) or as the number of failed CCA events during the carrier sensing operation. Collisions may thus be detected during the carrier sensing operation, or they may be detected during transmission of data, i.e. during the MCOT duration.

Interference from adjacent communication channel may not be so high as to hinder transmission in the current communication channel, however the interference may affect the quality of the transmission and may thus also be taken into consideration when estimating or determining the level of interference.

For instance, every time a transmission collision occurs, this may be logged and stored along with information on the interference from other sources. Stats on each performed LBT procedure may also be stored. The stored values may then indicate how often the channel is occupied or how often transmissions are interrupted due to e.g. collisions or other interference.

The level of interference may thus present a statistical value on how much interference/collision the channel historically has been subjected to. This history may be used to estimate the probability that there will be interference on the channel during transmission.

The method 500 may continue in 510 where the estimated level of interference is compared to an interference threshold. The interference threshold may e.g. be a value on the probability that there will be interference present in the channel when

transmitting, or that the transmission will be interrupted by a collision after a certain amount of time or something similar.

If this probability is higher than e.g. 40% or any other suitable percentage or value then it may be determined that the interference is larger than the interference threshold (N-path out of 510) and the method may continue in 512 where the priority level of the data left in the buffer is set to its original priority level, i.e. the first priority level.

If it in 510 is determined that the interference is less than the interference threshold (Y-path out of 510) then the probability of interference during transmission is small and the method may continue in 511 where the first priority level of the data that is left in the buffer is changed to a second priority level, in this case, a lower priority such as 3 or 4.

Then the method continues in 502 where a carrier sensing operation is performed having the parameters corresponding to the newly set priority level of the data that was left in the buffer.

Thus, the data which had the first priority level and that was not transmitted is transmitted with the second priority level. In this case, the method may further comprise monitoring the channel when transmitting (during MCOT) the data with changed priority and reverting to the first priority level if interference is detected in the communication channel during the data transmission (compare with steps 503, 504 and 502) of the method 500. Interference may e.g. be transmission collisions in the channel.

In some embodiments, the method may comprise increasing or decreasing the priority level based on the amount of successful CCA or number of received NACKs during transmission. Hence, a single collision or one successful LBT occasion may in some embodiments not result in a change of priority. As previously mentioned both methods 400 and 500 may be performed by a network node such as a base station or eNB. The communication network may be a long term evolution network. License Assisted Access may be used, e.g. LAA according to 3 GPP version 13.

The methods may be performed in both uplink and in downlink. They may also be performed by a wireless communication device such as mobile phone or the like.

The carrier sensing operation may be a LBT operation, and may be any of category 1, 2, 3 or 4 LBT according to the RAN 1 agreement for LBT in 3GPP LAA Fig. 6 illustrates an example arrangement 600 of a communication device 601 configured to operate in a communication network for improving performance in the communication network.

The arrangement 600 comprises a transceiver (RX/TX) 602 and a controller (CNTR) 604. The arrangement 600 may also comprise a memory (MEM) 603.

The controller 604 may further comprise a priority unit (PRIO) 605, a determiner (DET) 606, an interference unit (INT) 607 and a carrier sensing organ (CA) 608.

The controller may be configured to cause the carrier sensing organ 608 to perform a carrier sensing operation in a communication channel in order to determine whether a transmission activity is occurring in the communication channel (compare with step 402 and 502 of methods 400 and 500).

The carrier sensing operation may e.g. be a LBT operation as described in conjunction with any of the Figs. 1-5.

The controller 604 may also be configured to cause the transceiver 602 to start transmission of data intended for transmission in the communication channel during a channel occupation time if it is determined that no transmission activity is occurring in the communication channel (compare with steps 403 and 505 in method 400 and 500).

The carrier sensing organ 608 may e.g. determine that there is no transmission activity going on if e.g. LBT is used and a certain number clear channel assessment events resulted in acknowledgement of a clear channel (compare with Fig. 1 and step 503 of method 500). The controller 604 may then cause the determiner 606 to determine, when the channel occupation time has expired, whether all of the data intended for transmission has been transmitted (compare with step 404 and 506 of methods 400 and 500).

The determiner 606 may e.g. check in a buffer which may be comprised in the memory 603 if the buffer still contains data.

If not all data intended for transmission has been transmitted, the controller 604 may further be configured to cause the interference unit 607 to determine a level of interference in the communication channel (compare with step 406 and 509 of methods 400 and 500).

The interference unit 607 may e.g. store each determined interference level in the memory 603 and perform a computation of an estimated interference level based on each stored determined interference level.

The interference level may e.g. be based on at least one of a number of transmission collisions in the communication channel, number of unsuccessful carrier sensing operations, power of interference from an adjacent communication channel, detected interference in the network.

Thus the level of interference may at least partly be determined based on determined or estimated and stored previous levels and the current determined or estimated interference may be a value for the expected interference for a coming transmission.

If the interference unit 607 determines the level to be below an interference threshold, the controller 604 may be configured to cause the priority unit 605 to check a first priority level of the data that has not been transmitted and set a second priority level of the data that has not been transmitted based on the first priority level.

The priority unit 605 may also in some embodiments check the priority level prior to the interference unit 607 determining a level of interference (as described in conjunction with Fig. 5).

If the first priority level is of high priority, e.g. a priority 1 or 2 (compare with the priority level described in conjunction with any of the Figs. 1-5), and the interference level is low it may be beneficial to set the priority level to a lower priority level which has a higher transmission peak rate (compare with table 300 of Fig. 3), as this may improve the overall network performance. E.g. if network interference is low, and a large amount of data needs to be transmitted with high priority, then it is probable that not all data will be able to be transmitted during the short MCOT that is allocated to high priority data. Since the interference is low it is probable that every LBT period will result in a clear channel and an OK for transmission, but time has been wasted while performing the LBT procedure. If the priority level is instead lowered, the clear channel assessment of the LBT may take slightly longer than for the high priority, but in exchange the MCOT is considerably longer which increases the probability that all or a larger part of the data will be transmitted during one MCOT.

As mentioned above, the priority level may be indicative of a length of the channel occupation time, such that the length of the channel occupation time is increased if the priority level is decreased and decreased if the priority level is increased.

In the arrangement 600 the controller 604 may further be configured to cause the priority unit 605 to set the second priority level to the first priority level if it is determined (e.g. by the interference unit 607) that the level of interference is above the interference threshold (compare with steps 407, 408, 510, 512 of methods 400 and 500).

For various reasons it may not be beneficial to change the priority level if the expected or experienced interference in the communication channel is high since it may be crucial that high priority data is transmitted as soon as possible and low priority data will just have to wait.

The controller 604 may further be configured to cause the transceiver 602 to transmit the data that has not been transmitted but with the second priority level set instead of the first.

During transmission the controller 604 may cause the carrier sensing organ 608 to monitor the channel and communicate to the controller 604 if a transmission collision is detected in the channel (compare with step 503 of method 500). Since the data is not transmitted with its original priority it may be transmitted during a longer period of time which may interfere with other transmissions in a way it should not. In order to ensure that the channel is not occupied unnecessarily much thereby obstructing other data from being transmitted, the controller may upon receiving an indication that a collision was detected cause the priority unit 605 to perform a reversion to the first priority level if interference is detected in the communication channel during the data transmission (compare with step 503 of method 500).

The arrangement 600 may in some embodiments be configured to carry out any of the methods 400 and 500, or a combination of the two, as described in conjunction with Figs. 4 and 5.

The arrangement 600 may be implemented in a network node such as base station or eNB or the like, or in a wireless communication device such as a mobile terminal, lap top, surf pad etc.

The term arrangement is to be interpreted as a system of components that may be implemented in hardware or software and be configured to carry out program instructions. The term arrangement is in this disclosure not to be interpreted as a method, but rather as an apparatus configured to carry out method steps.

Fig. 7 illustrates a computer program product 700 comprising a computer readable medium 700, having thereon a computer program comprising program instructions. The computer program being loadable into a data-processing unit 701 comprising a memory (MEM) 702 and a processor (PROC) 703 and adapted to cause execution of method steps, e.g. the method steps as described in conjunction with any of the Figs. 4 and 5.

The disclosure describes a way to improve network efficiency by dynamically set a priority level of data to be transmitted in a network utilizing LAA. By changing the priority level based on an expected or experience level of interference in the

communication channel the transmission peak rate may be optimized. No violation is made to existing standards and the method is easily implemented in existing systems.

There is furthermore no risk that network traffic is affected due to high priority data being hindered as an effect of the change to lower priority. This since the channel is being monitored during transmissions and transmissions of data having changed priority may be immediately aborted if a collision is detected so as not to hinder other high priority data from being transmitted.

The described embodiments and their equivalents may be realized in software or hardware or a combination thereof. They may be performed by general-purpose circuits associated with or integral to a communication device, such as digital signal processors (DSP), central processing units (CPU), co-processor units, field- programmable gate arrays (FPGA) or other programmable hardware, or by specialized circuits such as for example application-specific integrated circuits (ASIC). All such forms are contemplated to be within the scope of this disclosure.

Embodiments may appear within an electronic apparatus (such as a wireless communication device and/or a network node) comprising circuitry/logic or performing methods according to any of the embodiments. The electronic apparatus may, for example, be a portable or handheld mobile radio communication equipment, a mobile radio terminal, a mobile telephone, a base station, a base station controller, a pager, a communicator, an electronic organizer, a smartphone, a computer, a notebook, a USB- stick, a plug-in card, an embedded drive, or a mobile gaming device.

According to some embodiments, a computer program product comprises a computer readable medium such as, for example, a diskette or a CD-ROM.

Reference has been made herein to various embodiments. However, a person skilled in the art would recognize numerous variations to the described embodiments that would still fall within the scope of the claims. For example, the method

embodiments described herein describes example methods through method steps being performed in a certain order. However, it is recognized that these sequences of events may take place in another order without departing from the scope of the claims.

Furthermore, some method steps may be performed in parallel even though they have been described as being performed in sequence.

In the same manner, it should be noted that in the description of embodiments, the partition of functional blocks into particular units is by no means limiting.

Contrarily, these partitions are merely examples. Functional blocks described herein as one unit may be split into two or more units. In the same manner, functional blocks that are described herein as being implemented as two or more units may be implemented as a single unit without departing from the scope of the claims.

Hence, it should be understood that the details of the described embodiments are merely for illustrative purpose and by no means limiting. Instead, all variations that fall within the range of the claims are intended to be embraced therein.

Claims

1. A method for improving performance of a communication network, the method comprising:

performing a carrier sensing operation in a communication channel in order to determine whether a transmission activity is occurring in the communication channel; transmitting data intended for transmission in the communication channel during a channel occupation time if it is determined that no transmission activity is occurring in the communication channel;

determining, when the channel occupation time has expired, whether all of the data intended for transmission has been transmitted; and if not:

determining a level of interference in the communication channel and, if the level of interference is determined to be below an interference threshold:

checking a first priority level of the data that has not been transmitted; and

setting a second priority level of the data that has not been transmitted based on the first priority level.

2. The method according to claim 1, wherein the priority level is indicative of a length of the channel occupation time, such that the length of the channel occupation time is increased if the priority level is decreased and decreased if the priority level is increased.

3. The method according to any of the previous claims, wherein the second priority level is set to the first priority level if it is determined that the level of interference is above the interference threshold.

4. The method according to any of the previous claims, further comprising transmitting the data that has not been transmitted with the second priority level; and reverting to the first priority level if interference is detected in the

communication channel during the data transmission.

5. The method according to any of the previous claims, further comprising storing each previously determined interference level in a memory; and wherein determining the level of interference comprises:

computing an estimated interference level based on the stored determined interference levels.

6. The method according to any of the previous claims, wherein the level of interference is based on at least one of a number of transmission collisions in the communication channel, a number of unsuccessful carrier sensing operations, a power of interference from an adjacent communication channel, and a detected interference in the network.

7. The method according to any of the previous claims, wherein the carrier sensing operation is a listen before talk - LBT - operation.

8. The method according to any of the previous claims, wherein the communication network utilizes License Assisted Access - LAA.

9. A computer program product comprising a computer readable medium, having thereon a computer program comprising program instructions, the computer program being loadable into a data-processing unit comprising a memory and a processor and adapted to cause execution of the method according to any of claims 1 through 8 when the computer program is run by the data-processing unit.

10. An arrangement of a communication device configured to operate in a communication network for improving performance of the communication network, wherein the arrangement comprises a transceiver and a controller, and wherein the controller is configured to cause: performance of a carrier sensing operation in a communication channel in order to determine whether a transmission activity is occurring in the communication channel;

transmission of data intended for transmission in the communication channel during a channel occupation time if it is determined that no transmission activity is occurring in the communication channel;

determination of, when the channel occupation time has expired, whether all of the data intended for transmission has been transmitted; and if not:

determination of a level of interference in the communication channel and, if the level of interference is determined to be below an interference threshold:

checking of a first priority level of data that has not been transmitted; and

setting of a second priority level of the data that has not been transmitted based on the first priority level.

11 The arrangement according to claim 10, wherein the priority level is indicative of a length of the channel occupation time, such that the length of the channel occupation time is increased if the priority level is decreased and decreased if the priority level is increased

12. The arrangement according to any of the claims 10-11, wherein the controller is configured to cause setting of the second priority level to the first priority level if it is determined that the level of interference is above the interference threshold.

13. The arrangement according to any of the claims 10-12, wherein the controller is further configured to cause:

transmission of the data with the second priority level that has not been transmitted; and

reversion to the first priority level if interference is detected in the

communication channel during the data transmission.

14. The arrangement according to any of the claims 10-13, wherein the controller is further configured to cause:

storage of each previously determined interference level in a memory; and wherein determining the level of interference comprises:

computation of an estimated interference level based on the stored determined interference levels.

15. The arrangement according to any of the claims 10-14, wherein the interference level is based on at least one of a number of transmission collisions in the communication channel, a number of unsuccessful carrier sensing operations, a power of interference from an adjacent communication channel, and detected interference in the network.

16. A network node comprising the arrangement according to any of the claims

10-15.

17. A mobile terminal comprising the arrangement according to any of the claims 10-15.