The disclosure relates to a wireless communication technique, and more particularly, to a scheduling method of uplink resource unit.
The wireless communication technology occupies an important proportion in modern technology. With continuous research and development in technology, an uplink resource allocation scheduling technology for the Internet of Things/mobile devices in Narrow_Band Internet of Thing (NB-IoT) in the field of 5G network communication has been proposed as a technology for enhancing reliability of devices in uploading data while reducing overall device power consumption by utilizing an integrated approach of repetition mechanism, radio resource allocation, modulation and transmit power configuration.
NB-IoT is expected to be one of promising IoT application technologies in the future, which can be easily deployed with use of existing network to support a large number of IoT devices for accessing networks and provide low cost and low energy transmission for extending battery life. Increasing the coverage and reliability by using repetition and multi-type resource unit (RU).
For NB-IoT-based technology, further research and development on an uplink data transmission method for achieving high reliability and energy-saving are still required.
The disclosure provides a base station and a scheduling method of uplink resource unit executed by the base station, which are capable of achieving a favorable uploading quality.
In an embodiment of the disclosure, a scheduling method of uplink resource unit between a user equipment and a base station server system in Narrow Band Internet of Thing (NB-IoT) includes: calculating an uplink parameter set having a minimized energy consumption according to a traffic and a QoS allowed by the user equipment, wherein the uplink parameter set comprises parameters of a plurality of allowed transmission variations including a number of scheduled resource units (NRU), a number of repetitions (Nrep), a number of consecutive subcarriers (NSC) used by the resource units and a modulation coding scheme (MCS). A score of a transmission condition variation of the user equipment is calculated by using a score function and a transmission order of the user equipment is determined according to the score. A disposing position of the resource units in uplink subcarriers is determined such that a remaining area of effective resource units is minimized. A transmission time of the disposing position is checked, and the number of consecutive subcarriers is changed when the transmission time does not satisfy a delay constraint. Here, the step of determining the disposing position of the resource units in the uplink subcarriers is looped back and performed with an energy consumption used by the resource unit being not changed as a higher priority, and an uplink resource unit scheduling is completed when the checking result satisfies the delay constraint.
In an embodiment of the disclosure, a base station server system includes: a processor, configured to perform a management on a communication of the base station with a user equipment; a storage apparatus, at least storing firmware or software required by the management performed by the processor; a buffer memory device, configured to temporarily store data required in operations of the processor; and a communication interface, providing an interface for communicating with the user equipment. Here, according to an NB-IoT specification, the processor performs an uplink resource unit scheduling, including calculating an uplink parameter set having a minimized energy consumption according to a traffic and a Quality of Service (QoS) allowed by the user equipment. Here the uplink parameter set comprises parameters of a plurality of allowed transmission variations including a number of scheduled resource units (NRU), a number of repetitions (Nrep), a number of consecutive subcarriers (NSC) used by the resource units and a modulation coding scheme (MCS). A score of a transmission condition variation of the user equipment is calculated by using a score function and a transmission order of the user equipment is determined according to the score. A disposing position of the resource units in uplink subcarriers is determined such that a remaining area of effective resource units is minimized. A transmission time of the disposing position is checked, and the number of consecutive subcarriers is changed when the transmission time does not satisfy a delay constraint. Here, the step of determining the disposing position of the resource units in the uplink subcarriers is looped back and performed with an energy consumption used by the resource unit being not changed as a higher priority, and an uplink resource unit scheduling is completed when the checking result satisfies the delay constraint.
To make the above features and advantages of the present disclosure more comprehensible, several embodiments accompanied with drawings are described in detail as follows.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
The disclosure proposes a scheduling method of resource unit during an uplink transmission in an NB-IoT specification, which can improve transmission quality including reliability enhancement and energy loss reduction.
Several embodiments are provided below to describe the disclosure, but the disclosure is not limited by the provided embodiments.
In the followings, the NB-IoT specification is described first so the resource units can be scheduled better after understanding variations allowed by the NB-IoT specification.
Referring to
During the uplink transmission, possible options are shown by Table 1.
NiSC is a number of consecutive subcarriers used by the resource unit in the uplink transmission.
Nislot is a number of consecutive slots used by the resource unit in the uplink transmission.
NULsymb is a number of the resource elements used by the slot.
Under the framework of the above specification, the disclosure can schedule uplink resource allocation to effectively use the bandwidth, save energy and maintain favorable transmission reliability.
In the disclosure, with use of the data size units, a number of scheduled data units (NRU) may be estimated. A data size Di may be estimated by, for example, Equation (1) below.
wherein f(MCSi) is a predetermined function based on a modulation coding scheme (MCS).
With various aforesaid adjustable factors taken into consideration, the disclosure proposes the scheduling method of uplink resource unit described in more details as follows.
In other words, the resource unit type may be selected and a parameter set satisfying the BER and the repetitions may be calculated according to a tone number, a MCS and a reliability for each user equipment (UE).
In a step S20, a score function is used to calculate a score of a transmission condition variation of the user equipment and a transmission order of the user equipment is determined according to the score.
In a step S30, a disposing position of the resource units in uplink subcarriers is determined such that a remaining spectrum resource is minimized.
In a step S40, a transmission time of the disposing position is checked to see whether or not a delay constraint allowed by the user equipment is satisfied.
If a result of the step S40 is true, it means that a result of checking the disposing position satisfies the delay constraint and a step S60 (End) can be entered to complete an uplink resource unit scheduling.
If the result of checking the disposing position in the step S40 is false, i.e., when the transmission time does not satisfy the delay constraint, the number of the consecutive subcarriers (NSC) is changed in a step S50. An effect of changing the number of consecutive subcarriers (NSC) is equivalent to changing the resource unit type or changing the tone number. Then, the step S30 of determining the disposing position of the resource units in the uplink subcarriers is looped back and performed.
Moreover, if the scheduling cannot be completed simply by changing the number of consecutive subcarriers (NSC), the method can go back to the step 20 in which a transmission configuration with a second highest score is selected for re-scheduling. In an embodiment, the method may also go back to the step S10 in which a configuration with a second highest energy consumption is selected. Those subsequent schedulings can still adopt the technique of the disclosure. For example, the minimized energy consumption in the step 10 will exclude the unavailable combinations which violate delay constrains.
Content of each step will be described in more details as follows. In the step S10, for example, according to Equation (1), the number of resource units NiRU may be estimated according to a data size Di of an ith user equipment. Also, a successful transmission probability PiS is may also calculated according to the bit error rate BER, as shown by Equation (2).
PiS=(1−BERi)Di (2)
Then, the number of repetitions NiREP is calculated, as shown by Equation (3). The number of repetitions NiREP needs to satisfy a requirement of Equation (3) to be greater than or equal of a reliability goal Ri of the ith UE.
1−(1−PiS)N
In addition, the selection of a received power Pi needs to be greater than a lowest power consumption calculated according to
Next, according to the previously obtained parameter values, an energy consumption Ei of Equation (4) is calculated.
Ei=Pi×Nislot×NiRU×Nirep (4)
Afterwards, those having the lowest energy consumption Ei among the parameter values are found and used as an initial uplink parameter set through a calculation shown in Equation (5).
Eimin=min ΣiEi (5)
After the lowest energy consumption is found accordingly, it can be determined that the parameters including NiSC, Nislot, NiRU, Nirep and MCSi have various options of 1/3/6/12. In the step S20, according to possible variation options in the transmission order of the user equipment, a higher flexibility can be provided for allowing variations to be adjusted later in a case of more options, which has a lower priority value. For instance:
In case of one option, a priority value (p)=4.
In case of two options, the priority value (p)=3.
In case of three options, the priority value (p)=2.
In case of more than three options, the priority value (p)=1.
Furthermore, if a time emergency is to be taken into consideration, an estimated value may also be obtained according to, for example, factors like a remaining time, etc. Then, the scores of the time emergency and the remaining time may be calculated according to weights W1 and W2, as shown by Equation (6):
(Score)i=W1*(priority value)i+W2*(time emergency)i (6)
The scores are shown in Table 2:
Accordingly, the disclosure further selects a UE with higher score and corresponding parameter set which includes NiSC=3 and Nirep=2.
In the step S30, the resource units are practically disposed into the radio frames.
Referring to
Next, since the determining result is “False” in the step S40, the method proceeds to a step S50, in which the resource unit type is changed (i.e., the tone number is changed).
A changing order may be determined according to, for example, a cost ratio. In the condition where allowable tone options are of 1, 3, 6 and 12, owing to the fact that 3 tones, 6 tones and 12 tones have the same energy consumption, there is not particular limitation on those options as long as the delay constraint can be satisfied (e.g., a smaller one or a greater one of any two of the options can be select first). The option of single tone is the secondary choice since it will change the energy consumption currently being used.
In this way, through a loop of S30, S40 and S50, the scheduling of the resource units during the uplink transmission may then be achieved. Under the framework of the NB-IoT specification, the disclosure schedules resource allocation to effectively use the bandwidth, save energy and maintain favorable transmission reliability.
By doing so, a system equipment for the scheduling method of uplink resource unit may be realized, and disposed in, for example, the base station server system.
Referring to
The NB-IoT technique of the disclosure is an uplink data transmission method with high reliability and power saving that provides a more preferable combination in terms of the number of repetitions and the resource unit type. Moreover, with proper combination of MCS and power selection, transmission efficiency can be improved while maintaining energy conservation.
Although the present disclosure has been described with reference to the above embodiments, it is apparent to one of the ordinary skill in the art that modifications to the described embodiments may be made without departing from the spirit of the present disclosure. Accordingly, the scope of the present disclosure will be defined by the attached claims not by the above detailed descriptions.
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