CN107205276B

CN107205276B - Method and apparatus for asymmetric band configuration of NB-IoT

Info

Publication number: CN107205276B
Application number: CN201610158123.7A
Authority: CN
Inventors: 刘海静; 王河
Original assignee: Nokia Shanghai Bell Co Ltd
Current assignee: Nokia Shanghai Bell Co Ltd
Priority date: 2016-03-18
Filing date: 2016-03-18
Publication date: 2021-05-07
Anticipated expiration: 2036-03-18
Also published as: CN107205276A

Abstract

The invention provides a method and a device for asymmetric frequency band configuration of NB-IoT. The method comprises the following steps: allocating an available DL frequency band set and an available UL frequency band set for all UEs served by a base station, wherein the number of frequency bands contained in the available DL frequency band set is not equal to the number of frequency bands contained in the available UL frequency band set; broadcasting information on the allocated available DL band set and available UL band set to all UEs served thereby through system information; detecting random access on an UL frequency band of one of all UEs, wherein the UL frequency band is selected from the set of available UL frequency bands; and determining a DL band for the UE from the set of available DL bands.

Description

Method and apparatus for asymmetric band configuration of NB-IoT

Technical Field

The present invention relates generally to the field of wireless communications, and more particularly, to a method and apparatus for asymmetric band configuration for NB-IoT.

Background

Narrowband Internet of Things (NB-IoT) is a technology that supports low-rate Machine-to-Machine (M2M) services, which is very low cost and easier to deploy in current cellular mobile (e.g., global system for mobile communications (GSM) and/or Long Term Evolution (LTE)) networks. The 3GPP RAN #69 approved NB-IoT and updated at RAN #70 to specify wireless access to the cellular internet of things, based largely on the non-backward compatible variant of the evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access (E-UTRA), which improves indoor coverage, supports a large number of low throughput devices, has low latency sensitivity, very low device cost, low device power consumption, and network architecture optimization (see reference [1 ]).

The NB-IoT supports 180kHz User Equipment (UE) Radio Frequency (RF) bandwidth for both Downlink (DL) and Uplink (UL). In RAN1NB-IoT ad hoc networks, support for multi-band NB-IoT has been agreed at least for in-band and guard-band operation modes (see reference [2 ]). One NB-IoT band, which is an anchor band, contains NB-Primary Synchronization Signal (PSS)/Secondary Synchronization Signal (SSS) and NB-Physical Broadcast Channel (PBCH), and the other bands are configured by a Master Information Block (MIB) and/or a System Information Block (SIB) and/or Radio Resource Control (RRC) signaling, but detailed signaling thereof is not yet specified.

Current multiband NB-IoT work focuses on symmetric DL/UL resource allocation. The DL/UL 180kHz bands are paired, and there is a one-to-one mapping between the DL and UL bands. However, considering NB-IoT traffic patterns, DL traffic and UL traffic are typically asymmetric, so a symmetric DL/UL band configuration is not good enough for spectrum utilization efficiency.

Reference documents:

[1]RP-152284,“Revised Work Item:Narrowband IoT(NB-IoT)”,RAN#70,Huawei,HiSilicon.

[2]“RAN1agreements for Rel-13NB-IoT”,RAN1#84,Ericsson.

disclosure of Invention

To this end, the present invention proposes an asymmetric band configuration scheme for NB-IoT, in which different numbers of bands are configured for DL and UL.

According to some embodiments of the present invention, there is provided a method for asymmetric band configuration of NB-IoT, the method comprising: allocating an available DL frequency band set and an available UL frequency band set for all UEs served by a base station, wherein the number of frequency bands contained in the available DL frequency band set is not equal to the number of frequency bands contained in the available UL frequency band set; broadcasting information on the allocated available DL band set and available UL band set to all UEs served thereby through system information; detecting random access on an UL frequency band of one of all UEs, wherein the UL frequency band is selected from the set of available UL frequency bands; and determining a DL band for the UE from the set of available DL bands.

According to further embodiments of the present invention, there is provided a method for asymmetric band configuration of NB-IoT, comprising: receiving information related to an available DL frequency band set and an available UL frequency band set allocated by a base station through system information, wherein the number of frequency bands contained in the available DL frequency band set is not equal to the number of frequency bands contained in the available UL frequency band set; selecting one UL frequency band from the set of available UL frequency bands for UL transmission by the UE; determining a DL band for the UE from the set of available DL bands; and performing a random access procedure on the selected UL frequency band.

According to other embodiments of the present invention, there is provided an apparatus for asymmetric band configuration of NB-IoT, comprising: a frequency band allocation unit, configured to allocate an available DL frequency band set and an available UL frequency band set for all UEs served by a base station, where the number of frequency bands included in the available DL frequency band set is not equal to the number of frequency bands included in the available UL frequency band set; a transmitting unit for broadcasting information on the allocated available DL band set and available UL band set to all UEs served thereby through system information; a detecting unit, configured to detect a random access on an UL frequency band of one of all UEs, wherein the UL frequency band is selected from the set of available UL frequency bands; and a DL band determination unit for determining a DL band for the UE from the set of available DL bands.

According to other embodiments of the present invention, there is provided an apparatus for asymmetric band configuration of NB-IoT, comprising: a receiving unit, configured to receive, from a base station through system information, information about an available DL frequency band set and an available UL frequency band set allocated by the base station, where a number of frequency bands included in the available DL frequency band set is not equal to a number of frequency bands included in the available UL frequency band set; a UL band selection unit configured to select one UL band from the set of available UL bands for UL transmission of the UE; a DL band determination unit for determining a DL band for the UE from the set of available DL bands; and a transmitting unit for performing a random access procedure on the selected UL frequency band.

With the asymmetric band configuration scheme for NB-IoT of the present invention, the band configuration can be dynamically adapted to different traffic DL/UL patterns of Long Term Evolution (LTE) systems and NB-IoT systems, and is particularly suited to in-band NB-IoT operational patterns.

Drawings

The present invention will be better understood and other objects, details, features and advantages thereof will become more apparent from the following description of specific embodiments of the invention given with reference to the accompanying drawings. In the drawings:

fig. 1 shows a flow diagram of an asymmetric band configuration method for NB-IoT in accordance with the present invention;

fig. 2 shows a schematic diagram of one example of an asymmetric band configuration for NB-IoT in accordance with the present invention;

fig. 3 shows a block diagram of an apparatus for asymmetric band configuration of NB-IoT in accordance with the present invention; and

fig. 4 shows a block diagram of an apparatus for asymmetric band configuration of NB-IoT in accordance with the present invention.

Detailed Description

Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

Currently, the DL/UL spectrum resources are typically symmetric. In a global system for mobile communications (GSM) network, paired DL/UL frequency bands are employed. The DL and UL bands are paired and indicated by the parameter absolute radio channel number (ARFCN). Once the frequency index is determined, the DL and UL bands are determined. In an LTE Frequency Division Duplex (FDD) network, a similar scheme is employed for symmetric DL/UL resource configuration.

In an in-band mode NB-IoT deployment, the NB-IoT utilizes Physical Resource Blocks (PRBs) within the normal LTE carrier. In particular, for IoT traffic such as security monitoring, mobile automatic reporting exception/periodic reporting, etc., the traffic is mainly in the UL direction, and the amount of traffic required in the DL direction is less than in the UL direction. In conventional applications of LTE networks, DL traffic is much larger than UL traffic due to the development of multimedia traffic, mobile internet browsing and downloading. If the same amount of resources is allocated for NB-IoT DL and UL (equivalent to the same amount of spectrum resources left for LTE DL and UL transmissions), then part of the NB-IoT DL spectrum resources and part of the LTE UL spectrum resources would be wasted.

To improve the utilization efficiency of limited spectrum resources, the present invention proposes an asymmetric band configuration scheme for NB-IoT, especially for in-band NB-IoT operation mode, where different numbers of bands are configured for NB-IoT DL and UL transmissions.

Fig. 1 shows a flow diagram of an asymmetric band configuration method 100 for NB-IoT in accordance with the present invention.

As shown in fig. 1, the NB-IoT includes a base station (e.g., eNB)1 and one or more NB-IoT UEs 2 served thereby. As an example, only one NB-IoT UE 2 is shown in fig. 1 to facilitate the following more detailed description.

In step 110, the base station 1 allocates available DL frequency band set and available UL frequency band set for all NB-IoT UE 2 served by the base station, wherein the number of frequency bands (denoted as N _ DL) included in the available DL frequency band set is not equal to the number of frequency bands (denoted as N _ UL) included in the available UL frequency band set. This is different from limiting N _ UL to be equal to N _ DL in a symmetric band configuration.

In one implementation, N _ DL is less than N _ UL given that NB-IoT's UL traffic demand is typically greater than DL traffic demand.

In step 120, the base station 1 broadcasts information on the allocated available DL band set and available UL band set to all NB-IoT UEs 2 it serves through system information.

In one implementation, the system information may be any one or more of MIB, SIB, RRC. Wherein the system information for the NB-IoT available bands is split into two parts, one for the DL bands and one for the UL bands.

In one implementation, base station 1 broadcasts index information for the frequency bands in the allocated set of available DL frequency bands and set of available UL frequency bands to NB-IoT UE 2. In another implementation, different sets of DL bands and UL bands correspond to different preset indicators in base station 1 and NB-IoT UE 2, so base station 1 broadcasts the respective indicators to NB-IoT UE 2.

In one implementation, the base station 1 broadcasts information on the allocated set of available DL bands and the set of available UL bands on its anchor band.

Thus, NB-IoT UE 2 accesses the NB-IoT system (e.g., on the anchor band) and acquires information about the available DL band set and the available UL band set allocated by base station 1.

Fig. 2 shows a schematic diagram of one example of an asymmetric band configuration for NB-IoT in accordance with the present invention.

As shown in fig. 2, assume that the NB-IoT system operates in an in-band mode of a 10MHz FDD LTE system. UL data transmission of NB-IoT systems requires 20 UL frequency bands. With the existing symmetric band configuration, 20 DL bands and 20 UL bands are configured for the NB-IoT system. Accordingly, the legacy LTE UE has only 30 DL bands and 30 UL bands left.

Considering the different traffic demands of normal LTE UEs and NB-IoT UEs, less than 20 frequency bands (e.g., 5 frequency bands, as shown in fig. 2) may be configured for DL NB-IoT only. Note that the NB-IoT anchor band is a special DL NB-IoT band. Thus, there are 45 DL bands available for legacy LTE DL transmission, so that the legacy LTE DL transmission will have a resource benefit of about 150%.

And for system information containing asymmetric NB-IoT band information, the total number of band indices is N _ UL + N _ DL-25, with 20 for UL bands and 5 for DL bands.

The DL and UL band allocation for a single UE before RRC connection is discussed next.

At step 130, a UE that wants to access an asymmetric NB-IoT system (e.g., NB-IoT UE 2 shown in fig. 1) selects one UL band from the set of available UL bands from base station 1 for its UL transmission. For example, after NB-IoT UE 2 receives MIB and PSS/SSS, it may receive SIBs and acquire information about available DL band set and available UL band set. A Physical Uplink Shared Channel (PUSCH) for uplink data transmission and a Physical Random Access Channel (PRACH) for random access of the UE are both transmitted on the UL frequency band.

In one implementation, NB-IoT UE 2 selects the UL frequency band based on parameters known to NB-IoT UE 2 according to a predetermined function. For example, these parameters may include a UE Identifier (ID), such as a globally unique temporary UE identity (GUTI) or International Mobile Subscriber Identity (IMSI), its own coverage level, the number of bands in the available UL band set (N _ UL), and so on.

To obtain balanced band selection, the band indices should be randomized. More preferably, therefore, the predetermined function may be a hash function, wherein the UE ID is contained in a hash key. For example, UE UL band index is UEID mod N _ UL.

Alternatively, NB-IoT UE 2 randomly selects the UL frequency band, where NB-IoT UE 2 directly generates a random integer from 1 to N _ UL as its UL frequency band index using a random number generator (e.g., a linear congruential generator).

At step 140, NB-IoT UE 2 performs a Random Access (RA) procedure on the selected UL frequency band (more specifically, on the PRACH).

In step 150, the base station 1 determines a DL band for the NB-IoT UE 2 from the set of available DL bands.

In one implementation, base station 1 may determine the DL band according to a predetermined function known to both base station 1 and NB-IoT UE 2, the parameters of which are known to both base station 1 and NB-IoT UE 2. In some examples, the parameters include one or more of a UL frequency band index of NB-IoT UE 2, a preamble index of NB-IoT UE 2, a coverage level of NB-IoT UE 2, and a number of frequency bands in the set of available DL frequency bands (N _ DL).

NB-IoT UE 2 can similarly determine its DL band. The determination of its DL band on the NB-IoT UE 2 side may be performed at any time after step 130, and may or may not be performed simultaneously with step 150. In this way, both NB-IoT UE 2 and base station 1 can know the DL band of NB-IoT UE 2 on which both the Physical Downlink Control Channel (PDCCH) and the Physical Downlink Shared Channel (PDSCH) of NB-IoT UE 2 are carried.

In another implementation, the mapping between UL and DL bands may be predefined (e.g., by base station 1), so once the UL band for NB-IoT UE 2 is determined, base station 1 and NB-IoT UE 2 may directly obtain the corresponding DL band index from the mapping. This can benefit in implementation complexity.

In this way, no control signals are required for band allocation for UEs in RRC idle state, which greatly reduces the control overhead for NB-IoT systems.

In this way, both NB-IoT UE 2 and base station 1 obtain the DL band index and UL band index of NB-IoT UE 2.

The following illustrates the determination process of the UL and DL bands of the NB-IoT UE 2.

In one example, NB-IoT UE 2 with UE id 460001234560001 wants to access an NB-IoT system with 20 (N _ UL) available UL bands and 5 (N _ DL) available DL bands. NB-IoT UE 2 may compute its UL frequency band index, which is 1, through UE id mod N _ UL, so NB-IoT UE 2 may use the first UL frequency band in the set of available UL frequency bands as its UL frequency band. NB-IoT UE 2 then performs the RA procedure on its UL frequency band. The NB-IoT UE 2 selects the second preamble and transmits on the PRACH. The base station 1 receives the preamble on the first UL band and determines its preamble index. Both NB-IoT UE 2 and base station 1 know that the UL band index is 1 and the preamble index is 2. Then, the DL band index of NB-IoT UE 2 is given by (UL band index × preamble index) mod N _ DL ═ 2. That is, the second DL band in the set of available DL bands is allocated to the NB-IoT UE 2. To this end, both NB-IoT UE 2 and base station 1 know the UL and DL band index of NB-IoT UE 2.

In another example, assume that NB-IoT UE 2 wants to access an NB-IoT system with 20 (N _ UL) available UL frequency bands and 5 (N _ DL) available DL frequency bands. The mapping between the UL band index and the DL band index is DL band index ceil (UL band index/4), where the function ceil (×) represents rounding up. For example, the corresponding DL bands of UL bands 1, 2, 3, and 4 are all DL band 1. NB-IoT UE 2 directly generates random number 11 as its UL frequency band index. According to the mapping relationship, the corresponding DL band index is 3.

Optionally, after the random access, the NB-IoT UE 2 enters the RRC connected state, at which time the method 100 may further include step 160, in which the base station 1 sends the updated DL band index and/or UL band index to the NB-IoT UE 2 through RRC signaling to adjust the band configuration of the NB-IoT UE 2. The band adjustment may take into account one or more factors, including load balancing of the entire network, coverage level of the UE and/or traffic pattern of the UE, etc.

When NB-IoT UE 2 receives the RRC signaling, it changes its DL band and/or UL band to the updated DL band index and/or UL band index. Otherwise, NB-IoT UE 2 remains in its existing UL and DL bands.

Fig. 3 shows a block diagram of an apparatus 300 for asymmetric band configuration of NB-IoT in accordance with the present invention. The apparatus 300 may be implemented, for example, in a base station (e.g., base station 1 shown in fig. 1).

As shown in fig. 3, the apparatus 300 includes: a frequency band allocating unit 310, configured to allocate an available DL frequency band set and an available UL frequency band set for all UEs served by a base station, where the number of frequency bands included in the available DL frequency band set is not equal to the number of frequency bands included in the available UL frequency band set; a transmitting unit 320 for broadcasting information on the allocated available DL band set and available UL band set to all UEs served thereby through system information; a detecting unit 330, configured to detect a random access on an UL frequency band of one UE among all UEs, wherein the UL frequency band is selected from the available UL frequency band set; and a DL band determining unit 340 for determining a DL band for the UE from the set of available DL bands.

In one implementation, the number of frequency bands included in the set of available DL frequency bands is less than the number of frequency bands included in the set of available UL frequency bands.

In one implementation, index information for the frequency bands in the allocated set of available DL frequency bands and the set of available UL frequency bands is broadcast to all UEs.

In one implementation, when different sets of DL bands and UL bands correspond to different preset indicators in the base station and all UEs, the corresponding indicators are broadcast to all UEs.

In one implementation, information regarding the allocated set of available DL bands and the set of available UL bands is broadcast on an anchor band.

In one implementation, the DL band is determined according to a predetermined function known to both the base station and the UE.

In one implementation, the DL band is determined according to a predetermined mapping relationship between the UL band and the DL band.

Fig. 4 shows a block diagram of an apparatus 400 for asymmetric band configuration of NB-IoT in accordance with the present invention. The apparatus 400 may be implemented, for example, in a UE (e.g., NB-IoT UE 2 as shown in fig. 1).

As shown in fig. 4, the apparatus 400 includes: a receiving unit 410, configured to receive, from a base station through system information, information about an available DL frequency band set and an available UL frequency band set allocated by the base station, where a number of frequency bands included in the available DL frequency band set is not equal to a number of frequency bands included in the available UL frequency band set; an UL band selecting unit 420, configured to select one UL band from the available UL band set for UL transmission of the UE; a DL band determining unit 430 for determining a DL band for the UE from the available DL band set; and a transmitting unit 440 for performing a random access procedure on the selected UL frequency band.

In one implementation, the UL frequency band is selected based on parameters known to the UE according to a predetermined function.

In one implementation, the predetermined function is a hash function and the UE ID is included in a hash key.

In one implementation, the UL frequency band is randomly selected.

By using the scheme of the invention, due to the asymmetric characteristic of NB-IoT service, data service is mainly concentrated in the UL direction, so that spectrum resources can be more effectively and flexibly used. On the other hand, temporary situations that require more traffic in the DL direction can be managed through Operator Administration and Maintenance (OAM), for example, for the purpose of NB-IoT UE software/firmware (SW/FW) upgrade, etc.

The methods disclosed herein are described herein with reference to the accompanying drawings. It should be understood, however, that the order of steps shown in the drawings and described in the specification is merely exemplary and that the method steps and/or actions may be performed in a different order and are not limited to the specific order shown in the drawings and described in the specification without departing from the scope of the claims.

In one or more exemplary designs, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. Such computer-readable media can comprise, for example, but is not limited to, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of instructions or data structures and which can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but, in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the present invention. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the present invention is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for asymmetric band configuration for NB-IoT, comprising:

allocating an available DL frequency band set and an available UL frequency band set for all UEs served by a base station, wherein the number of frequency bands contained in the available DL frequency band set is not equal to the number of frequency bands contained in the available UL frequency band set;

broadcasting information on the allocated available DL band set and available UL band set to all UEs served thereby through system information;

detecting random access on an UL frequency band of one of all UEs, wherein the UL frequency band is selected by the UE from the set of available UL frequency bands; and

determining a DL band for the UE from the set of available DL bands,

wherein determining a DL band for the UE from the set of available DL bands comprises:

the DL band is determined according to a predetermined function known to both the base station and the UE, wherein the parameters of the predetermined function comprise at least the UL band index of the UE.

2. The method of claim 1, wherein the number of frequency bands included in the available DL frequency band set is less than the number of frequency bands included in the available UL frequency band set.

3. The method of claim 1, wherein broadcasting information about the allocated set of available DL bands and the set of available UL bands to all UEs served thereby through system information comprises:

broadcasting index information of the frequency bands in the allocated available DL frequency band set and available UL frequency band set to all the UEs.

4. The method of claim 1, wherein broadcasting information about the allocated set of available DL bands and the set of available UL bands to all UEs served thereby through system information comprises:

broadcasting respective indicators to the all UEs when different sets of DL bands and sets of UL bands correspond to different preset indicators in the base station and the all UEs.

5. The method of claim 1, wherein broadcasting information about the allocated set of available DL bands and the set of available UL bands to all UEs served thereby through system information comprises:

information on the allocated available DL band set and available UL band set is broadcast on the anchor band.

6. The method of claim 1, wherein the first and second light sources are selected from the group consisting of a red light source, a green light source, and a blue light source,

the DL band is determined according to a predetermined mapping relationship between UL and DL bands.

7. A method for asymmetric band configuration for NB-IoT, comprising:

receiving information related to an available DL frequency band set and an available UL frequency band set allocated by a base station through system information, wherein the number of frequency bands contained in the available DL frequency band set is not equal to the number of frequency bands contained in the available UL frequency band set;

selecting one UL frequency band from the set of available UL frequency bands for UL transmission by the UE;

determining a DL band for the UE from the set of available DL bands; and

performing a random access procedure on the selected UL frequency band,

8. The method of claim 7, wherein the number of frequency bands included in the available DL band set is less than the number of frequency bands included in the available UL band set.

9. The method of claim 7, wherein selecting one UL band from the set of available UL bands for its UL transmission comprises:

selecting the UL frequency band based on a parameter known to the UE according to a predetermined function.

10. The method of claim 9, wherein the predetermined function is a hash function and the UE ID is included in a hash key.

11. The method of claim 7, wherein selecting one UL band from the set of available UL bands for its UL transmission comprises:

the UL frequency band is randomly selected.

12. The method of claim 7, wherein determining the DL band for the UE from the set of available DL bands comprises:

13. An apparatus for asymmetric band configuration for NB-IoT, comprising:

a frequency band allocation unit, configured to allocate an available DL frequency band set and an available UL frequency band set for all UEs served by a base station, where the number of frequency bands included in the available DL frequency band set is not equal to the number of frequency bands included in the available UL frequency band set;

a transmitting unit for broadcasting information on the allocated available DL band set and available UL band set to all UEs served thereby through system information;

a detecting unit configured to detect a random access on an UL frequency band of one of all UEs, wherein the UL frequency band is selected by the UE from the available UL frequency band set; and

a DL band determination unit for determining a DL band for the UE from the set of available DL bands,

14. An apparatus for asymmetric band configuration for NB-IoT, comprising:

a receiving unit, configured to receive, from a base station through system information, information about an available DL frequency band set and an available UL frequency band set allocated by the base station, where a number of frequency bands included in the available DL frequency band set is not equal to a number of frequency bands included in the available UL frequency band set;

a UL band selection unit configured to select one UL band from the set of available UL bands for UL transmission of the UE;

a DL band determination unit for determining a DL band for the UE from the set of available DL bands; and

a transmitting unit for performing a random access procedure on the selected UL frequency band,