TWI647965B - Method and apparatus for narrowband physical downlink control channel decoding - Google Patents

Abstract

A narrowband physical downlink control channel (NB-PDCCH) design for a narrowband Internet of Things (IoT) device is proposed. In one novel aspect, the NB-PDCCH spans the first and second time slots in the region of the legacy physical downlink shared channel (PDSCH). A plurality of physical resource blocks (PRBs) are allocated for NB-PDCCH transmission carrying Downlink Control Information (DCI). Furthermore, each NB-IoT device may be configured with n _PRB PRB pairs for NB-PDCCH transmission (eg, n _PRB =1, 2, 4 or 8), and the NB-PDCCH transmission time interval (TTI) is n _PRB sub-frames. The NB-PDCCH is encoded and occupies a plurality of narrowband control channel elements (NCCEs) based on the aggregation level. In a preferred embodiment, each PRB pair for the NB-PDCCH occupies two NCCEs.

Description

Method and device for decoding narrowband entity downlink control channel

Embodiments of the present invention generally relate to a Physical Downlink Control Channel (PDCCH), and more particularly to a PDCCH design for a narrowband Internet of Things (NB-IoT).

In a 3GPP Long Term Evolution (LTE) network, an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) includes a plurality of base stations, such as an evolved Node B (eNB) communicating with a plurality of mobile stations as user equipment (UE). Orthogonal Frequency Division Multiple Access (OFDMA) has been chosen for LTE downlink (DL) radio access schemes due to its robustness to multipath fading, higher spectral efficiency and bandwidth scalability. Multiple access in the downlink is achieved by allocating different sub-bands (ie, sub-carrier groups, represented as resource blocks (RBs)) to individual users based on their previous channel conditions. In an LTE network, a Physical Downlink Control Channel (PDCCH) is used for dynamic downlink scheduling. Typically, the PDCCH may be configured to occupy the first, first two or first three OFDM symbols in the subframe.

One promising technique for LTE is to implement spatial division multiplexing using multiple input multiple output (MIMO) antennas to further increase spectral efficiency gain. Multi-user MIMO (MU-MIMO) is considered in LTE Rel-10. In order to enable MU-MIMO, separate control signaling must be indicated to each UE through the PDCCH. Therefore, as each subframe needs to be increased in the number of scheduled UEs, it can be expected that more PDCCH transmissions are expected to be used. However, a PDCCH region of up to 3 symbols may not be sufficient to accommodate the increased number of UEs in LTE. Due to the limited capacity of the control channel, the performance of MIMO is reduced due to unoptimized MU-MIMO scheduling.

LTE-Advanced (LTE-A) systems increase spectrum efficiency by utilizing different sets of base stations deployed in heterogeneous network topologies. Using a mix of macro, pico, femto and relay base stations, heterogeneous networks enable flexible and low-cost deployments and provide a unified broadband user experience. In heterogeneous networks (HetNet), smarter resource coordination between base stations, better base station selection strategies, and advanced technologies for effective interference management can be delivered compared to traditional homogeneous networks. Significant benefits in terms of volume and user experience. For example, coordinated multiple points (CoMP) transmission/reception (also referred to as multi-BS/site MIMO) is used to enhance the performance of cell edge UEs in LTE-Rel-11. CoMP produces a control channel capacity problem similar to the MU-MIMO case described above.

In order to solve the problem of control channel capacity, a UE-specific downlink scheduler for MU-MIMO/CoMP has been proposed. In LTE, it extends the PDCCH design to the new ePDCCH in the legacy physical downlink shared channel (PDSCH). The main benefit of having this new physical control channel is better support for HetNet, CoMP and MU-MIMO. Based on the ePDCCH design in the first and second time slots in the legacy PDSCH region, it is desirable to design the ePDCCH to support the decentralized and localized transmission entity structure to utilize diversity or beamforming gain. In order to minimize control overhead, resource utilization gains need to be enhanced, and physical resources for decentralized and localized transmission of ePDCCH may need to be multiplexed in one physical resource block (PRB).

The narrowband Internet of Things (NB-IoT) is a low power wide area network (LPWAN) radio technology standard that has been developed to enable the use of cellular communications to connect a wide range of devices and servos. NB-IoT is a narrowband radio technology designed for the Internet of Things (IoT) and is one of a series of Mobile Internet of Things (MIoT) technologies standardized by 3GPP. The physical structure used for the NB-IoT physical downlink control channel needs to be solved.

A narrowband physical downlink control channel (NB-PDCCH) design for narrowband Internet of Things (IoT) devices is proposed. In one novel aspect, the NB-PDCCH spans the first and second time slots in the region of the legacy physical downlink shared channel (PDSCH). A plurality of physical resource blocks (PRBs) are allocated for NB-PDCCH transmission carrying Downlink Control Information (DCI). Furthermore, each NB-IoT device may be configured with n _PRB PRB pairs for NB-PDCCH transmission (eg, n _PRB =1, 2, 4 or 8), and the NB-PDCCH transmission time interval (TTI) is n _PRB sub-frames. The NB-PDCCH is encoded and occupies a plurality of narrowband control channel elements (NCCEs) based on the aggregation level. In a preferred embodiment, each PRB pair for the NB-PDCCH occupies two NCCEs.

In one embodiment, a method of receiving and decoding downlink control information on an NB-PDCCH through an NB-IoT device is disclosed. The UE receives the control signal to determine a received Physical Resource Block (PRB) carrying Downlink Control Information (DCI). The UE determines a set of candidate narrowband physical downlink control channels (NB-PDCCHs) within the PRB, where each NB-PDCCH is associated with a set of narrowband control channel elements (NCCEs) for NB-PDCCH transmission. The UE collects a plurality of resource elements (REs) for each NCCE, where each NCCE consists of a plurality of REs based on NCCE to RE demapping rules. The UE decodes downlink control information (DCI) that is mapped to the collected RE.

In another embodiment, a method for encoding and transmitting downlink control information through an NB-PDCCH for an NB-IoT device is disclosed. A network device (eg, a servo base station) sends control signals. A set of physical resource blocks (PRBs) are allocated to carry Downlink Control Information (DCI). The base station determines a set of candidate narrowband physical downlink control channels (NB-PDCCHs) within the PRB. Each NB-PDCCH is associated with a set of narrowband control channel elements (NCCEs) to potentially carry DCI. The base station maps a plurality of resource elements (REs) to each NCCE based on the RE to NCCE mapping rules. If the DCI is for the UE, the base station encodes the downlink control information through a set of NCCEs to be transmitted to the UE.

Other embodiments and advantages are described in the detailed description that follows. This summary is not intended to limit the invention. The invention is defined by the scope of the patent application.

100‧‧‧Mobile communication network

101‧‧‧Evolved Node B

102, 103, 104‧‧‧ User equipment

110‧‧‧Narrowband physical downlink control channel

201‧‧‧Base station

202‧‧‧ memory

203‧‧‧ processor

204‧‧‧Encoder

205‧‧‧ mapping module

206‧‧‧Transceiver

207‧‧‧Antenna

208‧‧‧Control Module

209‧‧‧Program instructions and information

211‧‧‧User equipment

212‧‧‧ memory

213‧‧‧ processor

214‧‧‧Decoder

215‧‧‧ Collector

216‧‧‧ transceiver

217‧‧‧Antenna

218‧‧‧Control Module

219‧‧‧Program instructions and information

901, 902, 903, 904, 1001, 1002, 1003, 1004 ‧ ‧ steps

Figure 1 illustrates a mobile communication network utilizing a narrowband physical downlink control channel (NB-PDCCH) in accordance with one novel aspect.

Figure 2 shows a simplified block diagram of a base station and user equipment in accordance with an embodiment of the present invention.

Figure 3 shows an example of the NB-PDCCH and the physical structure of a narrowband control channel element (NCCE) with local narrowband resource element group (NREG) or resource element (RE) to NCCE mapping.

Figure 4 shows an example of different NB-PDCCH formats, each NB-PDCCH having a corresponding number of NCCEs and a corresponding number of REs.

Figure 5 shows a first example of an NCCE to NB-PDCCH mapping with two PRBs.

Figure 6 shows a second example of an NCCE to NB-PDCCH mapping with four PRBs.

Fig. 7 shows an example of an NB-PDCCH search space for an NB-IoT device.

Fig. 8 shows an example of NB-PDCCH blind decoding based on the NB-PDCCH search space.

Figure 9 is a flow diagram of a method of receiving and decoding downlink control information on an NB-PDCCH by an NB-IoT device in accordance with one novel aspect.

Figure 10 is a flow diagram of a method of encoding and transmitting downlink control information over an NB-PDCCH over a NB-IoT device in accordance with one novel aspect.

Reference will now be made in detail to the preferred embodiments of embodiments

1 shows a mobile communication network 100 utilizing a narrowband physical downlink control channel (NB-PDCCH) in accordance with one novel aspect. The mobile communication network 100 is an OFDM/OFDMA system including a base station (evolved Node B eNodeB) 101 and a plurality of user equipments UE 102, UE 103 and UE 104. When there are downlink packets to be transmitted from the eNodeB to the UE, each UE obtains a downlink assignment, such as a set of radio resources in a Physical Downlink Shared Channel (PDSCH). When the UE needs to transmit a packet to the eNodeB in the uplink, the UE obtains a license from the eNodeB to allocate a Physical Uplink Shared Channel (PUSCH) consisting of a set of uplink radio resources. The UE is specific to the UE. The downlink downlink control channel (PDCCH) obtains downlink or uplink scheduling information. In addition, broadcast control information is also transmitted to all UEs in the cell in the PDCCH. The downlink or uplink scheduling information and broadcast control information carried by the PDCCH are referred to as Downlink Control Information (DCI).

In the example of FIG. 1, the eNodeB 101 transmits a DCI to the UE using a narrowband physical downlink control channel (NB-PDCCH) 110. In an OFDMA downlink-based 3GPP LTE system, radio resources are divided into a plurality of subframes, wherein each subframe consists of two slots, and each slot contains seven OFDMA symbols along the time domain. Depending on the system bandwidth, each OFDMA symbol is further composed of a plurality of OFDMA subcarriers along the frequency domain. The basic unit of the resource grid is called a resource element (RE), which occupies one OFDMA subcarrier in the frequency domain and occupies one OFDMA symbol in the time domain. A physical resource block (PRB) occupies one time slot and twelve subcarriers, while a PRB pair occupies two consecutive time slots. In one novel aspect, NB-PDCCH 110 spans the first and second time slots in the region of the PRB pair. In addition, each UE may be configured with n _PRB PRB pairs for NB-PDCCH transmission (eg, n _PRB =1, 2, 4, or 8), and NB-PDCCH transmission time interval (TTI) is n _PRB sub-messages Frame composition. In the example of FIG. 1, NB-PDCCH 110 is encoded and occupies a plurality of narrowband control channel elements (NCCEs). The RE is mapped to the NCCE to form a logical unit carrying the DCI.

Figure 2 shows a simplified block diagram of a base station 201 and user equipment 211 in accordance with an embodiment of the present invention. For base station 201, antenna 207 transmits and receives radio signals. A radio transceiver 206 coupled to the antenna receives a radio signal from the antenna, converts it to a baseband signal, and transmits it to the processor 203. The radio transceiver 206 also converts the received baseband signal from the processor into a radio signal and transmits it to the antenna 207. The processor 203 processes the received baseband signals and invokes different functional modules to perform the characteristics of the base station 201. Memory 202 stores program instructions and data 209 to control the operation of the base station.

A similar configuration exists in the user device 211 in which the antenna 217 transmits and receives radio signals. The radio transceiver module 216 coupled to the antenna receives radio signals from the antenna, converts them to baseband signals and transmits them to the processor 213. The radio transceiver 216 will also receive from the processor The baseband signal is converted to a radio signal and sent to the antenna 217. The processor 213 processes the received baseband signals and invokes different functional modules to perform the features in the user device 211. The memory 212 stores program instructions and data 219 to control the operation of the user device.

Base station 201 and user equipment 211 also include a number of functional modules to perform some embodiments of the present invention. Different functional modules can be implemented by software, carcass, hardware or any combination thereof. When the functional modules are executed by the processors 203 and 213 (e.g., by executing program instructions and data 209 and 219), for example, the base station 201 is allowed to encode and transmit downlink control information to the user device 211, and the user device is allowed. 211 receives and decodes downlink control information. In one example, base station 201 configures a set of radio resources for NB-PDCCH transmission via control module 208 and maps downlink control information to configured resource elements via mapping module 205. The downlink control information carried in the NB-PDCCH is then modulated and encoded by the encoder 204 and then transmitted by the transceiver 206 via the antenna 207. User equipment 211 receives downlink control information via antenna 217 via transceiver 216. The user equipment 211 determines the configured radio resources for NB-PDCCH transmission via the control module 218 and collects the configured resource elements via the collector 215. The user equipment 211 then demodulates and decodes the downlink information from the collected resource elements via the decoder 214.

The physical structure of the NB-PDCCH may be two layers. In order to perform better diversity of decentralized and localized transmissions in the NB-PDCCH, a two-level entity structure is defined. The first layer is a physical unit of a narrowband resource element group (NREG), where the RE group is predefined for each NREG. The NREG may be grouped together or dispersed within a PRB or PRB pair. The second layer is the logical unit of the Narrowband Control Channel Element (NCCE), where the NREG is predefined or configured by the higher layers of each NCCE. Downlink control information is transmitted on a plurality of aggregated NCCEs depending on the desired modulation and coding level.

In a two-layer physical structure, the NCCE consists of several NREGs in a single PRB or a plurality of PRBs. For the NB-PDCCH decentralized transmission, the NCCE consists of a plurality of NREGs distributed over a plurality of discrete PRBs spread over the entire channel frequency, so that the distributed NCCE structure can be maximized. The frequency diversity gain is utilized. For local transmission of NB-PDCCH, the NCCE is composed of a plurality of NREGs uniformly distributed in a single PRB, so as to uniformly utilize the reference signal within one PRB to improve the robustness of the channel estimation. If the NREG of the NCCE is located in a local area within a PRB, the channel estimate will be heavily dependent on the reference signal near the NREG, so if these reference signals are interfered, the channel estimation performance will be greatly reduced. A uniformly distributed NREG can mitigate this effect.

To simplify the design, the physical structure of the NB-PDCCH can also be a single layer. In a single layer entity structure, the concept of NREG is eliminated. The single layer is a logical unit of a narrowband control channel element (NCCE), where the RE group is predefined or configured by a higher layer of each NCCE. Downlink control information is transmitted on a plurality of aggregated NCCEs depending on the desired modulation and coding level.

Figure 3 shows an example of the physical structure of the NB-PDCCH and the narrowband control channel element (NCCE), in this example, with local NREG and local NREG/RE to NCCE mapping. As shown in FIG. 3, the NB-PDCCH is allocated in one PRB or PRB pair having a plurality of resource elements (REs). The RE is allocated for data such as cell-specific reference signals (CRS), UE-specific reference signals (DM-RS), and channel state information reference signals (CSI-RS) or reference signals. NREG is a set of physically consecutive REs. In Figure 3, one NREG consists of two consecutive REs. For example, two adjacent REs for 2TX spatial frequency block coding (SFBC) are grouped into NREGs. In addition, an NCCE consists of a plurality of NREGs uniformly distributed in a single PRB. For example, 1NCCE=36NREGs=72REs. For a single layer entity structure, the concept of NREG is eliminated and the NCCE is mapped directly to the RE. In a preferred embodiment, each PRB pair for the NB-PDCCH occupies two NCCEs. Specifically, the allocated PRB for the NB-PDCCH is divided into two parts along the frequency domain. The REs belonging to the lower half of the subcarriers are mapped to NCCE-0, and the REs belonging to the upper half of the subcarriers are mapped to NCCE-1.

Figure 4 shows an example of a different NB-PDCCH format in which each NB-PDCCH has a corresponding number of NCCEs and each NB-PDCCH has a corresponding number of REs. The UE may be configured with n _PRB RRB pairs for NB-PDCCH transmission (eg, n _PRB =1, 2, 4, or 8), and the NB-PDCCH transmission time interval (TTI) is composed of n _{PRB subframes} . Each NB-PDCCH is encoded and occupies a plurality of NCCEs. As shown in the table 400 of Figure 4, many possible NB-PDCCH formats can be used. For NB-PDCCH format 0, each NB-PDCCH occupies one NCCE, for example, the aggregation level AL=1, and the number of REs per NB-PDCCH is 72. For NB-PDCCH format 1, each NB-PDCCH occupies two NCCEs, for example, an aggregation level of AL=2, and the number of REs per NB-PDCCH is 144. For NB-PDCCH format 2, each NB-PDCCH occupies four NCCEs, for example, aggregation level AL=4. For NB-PDCCH format 3, each NB-PDCCH occupies eight NCCEs, for example, aggregation level AL=8, and the number of REs per NB-PDCCH is 576. For NB-PDCCH format 4, each NB-PDCCH occupies 16 NCCEs, for example, aggregation level AL=16, and the number of REs per NB-PDCCH is 1152. Note that the number of repetitions R is further defined for the NB-PDCCH TTI.

Figure 5 shows a first example of an NCCE to NB-PDCCH mapping with two PRBs. In the example of FIG. 5, the UE is configured with two PRB pairs, and the NB-PDCCH TTI is composed of two subframes n and n+1. For NB-PDCCH format 1, the aggregation level AL=1 indicates that each NB-PDCCH occupies one NCCE, and each NCCE occupies half of the sub-frames in the frequency domain of the sub-carrier. As shown in FIG. 5, there are a total of four candidate NB-PDCCHs (NB-PDCCH-0, NB-PDCCH-1, NB-PDCCH-2, and NB-PDCCH-3) in subframes n and n+1. Shaded area. For NB-PDCCH format 2, the aggregation level is AL=2, that is, each NB-PDCCH occupies two NCCEs, and two NCCEs occupy the entire subframe. As shown in FIG. 5, there are a total of two candidate NB-PDCCHs (NB-PDCCH-0 and NB-PDCCH-1) in subframes n and n+1, which have different shaded areas.

Figure 6 shows a second example of NCCE to NB-PDCCH mapping with four PRBs. In the example of FIG. 6, the UE is configured with four PRB pairs, and the NB-PDCCH TTI is composed of four subframes n, n+1, n+2, and n+3. For NB-PDCCH format 1, the aggregation level AL=1 indicates that each NB-PDCCH occupies one NCCE, and each NCCE occupies half of the sub-frames in the frequency domain of the sub-carrier. There are a total of four candidate NB-PDCCHs (NB-PDCCH-0, NB-PDCCH-1, NB-PDCCH-2 and in subframes n and n+1). NB-PDCCH-3), as shown at the top of Figure 6, with different shaded areas. For NB-PDCCH format 2, the aggregation level is AL=2, that is, each NB-PDCCH occupies two NCCEs, and two NCCEs occupy the entire subframe. As shown at the bottom of FIG. 6, four candidate NB-PDCCHs (NB-PDCCH-0, NB-PDCCH-1, NB) having different shaded areas are shared among the subframes n, n+1, n+2 and n. - PDCCH-2 and NB-PDCCH-3).

In order to decode the NB-PDCCH specifically for the UE, the UE needs to find out where its NB-PDCCH is. In the so-called "blind" decoding process, the UE must try a plurality of candidate NB-PDCCHs before knowing which NB-PDCCH is its own target. The radio resources allocated for the candidate NB-PDCCH may be distributed or local. In addition, the NB-PDCCH may constitute a Common Search Space (CSS) or a UE-specific Search Space (UESS). As a result, the aggregated radio resources of the candidate NB-PDCCHs for different UEs may be different. In other words, the NB-PDCCH may be UE-specific and beneficial for blind decoding. With the UE-specific NB-PDCCH, the number of blind decoding candidates can be reduced without affecting the block rate of the downlink scheduler and the uplink grant, and the search space size of each UE can be reduced, so that the UE can enjoy shorter DCI detection. Processing time.

Fig. 7 shows an example of an NB-PDCCH search space for an NB-IoT device. In the example of FIG. 7, the radio resources allocated for the candidate NB-PDCCH constitute a UE-specific search space. In addition, the NB-PDCCH is of a local type, in which the radio resources used by the local NB-PDCCH are within one or a group of consecutive PRBs. The UE-specific NB-PDCCH search space may be represented by a set of parameters {AL, R, C}. The parameter AL indicates the aggregation level, for example the number of NCCEs per NB-PDCCH. If AL=1, it means that each NB-PDCCH occupies half of the subframe. If AL=2, it means that each NB-PDCCH occupies one subframe. The parameter R indicates the number of repetitions of the NB-PDCCH TTI repetition. The parameter C indicates the number of candidate NB-PDCCHs in the search space. In Fig. 7, four possibilities can be expressed by {2, Rmax/8, 8}, {2, Rmax/4, 4}, {2, Rmax/2, 2} and {2, Rmax, 1}. Search space, where Rmax>=8, a total of 15 blind decoding.

Figure 8 shows an illustration of NB-PDCCH blind decoding based on NB-PDCCH search space example. In the example of FIG. 8, the UE is configured with four PRB pairs, and the NB-PDCCH TTI is composed of four subframes n, n+1, n+2, and n+3. First, the UE determines a PRB or PRB pair configured for NB-PDCCH transmission based on signaling from the base station. The signaling may be dynamic signaling (layer 1 signaling), semi-static signaling (RRC signaling), system information, or any combination thereof. The UE decodes the signaling to determine a PRB or PRB pair allocated for NB-PDCCH transmission. Next, the UE divides each PRB into a plurality of NCCEs according to a predefined or configured partitioning rule, and then determines the logical address of each NCCE. Next, the UE follows another predefined or configured aggregation rule to aggregate a plurality of NCCEs into a single candidate NB-PDCCH. Since the downlink control information is transmitted by the base station on one or more logical NCCEs, the UE can decode the downlink control information based on the logical address of the NCCE.

Figure 9 is a flow diagram of a method of receiving and decoding downlink control information on an NB-PDCCH by an NB-IoT device in accordance with one novel aspect. In step 901, the UE receives a control signal to determine a received Physical Resource Block (PRB) carrying Downlink Control Information (DCI). In step 902, the UE determines a set of candidate narrowband physical downlink control channels (NB-PDCCHs) within the PRB, wherein each NB-PDCCH is associated with a set of narrowband control channel elements (NCCEs) for NB-PDCCH transmission Union. In step 903, the UE collects a plurality of resource elements (REs) for each NCCE, wherein each NCCE consists of a plurality of resource elements RE based on NCCE to RE demapping rules. Finally, in step 904, the UE decodes downlink control information (DCI) that is mapped to the collected resource element RE.

Figure 10 is a flow diagram of a method of encoding and transmitting downlink control information over an NB-PDCCH over a NB-IOT device in accordance with one novel aspect. In step 1001, the network device sends a control signal. A set of physical resource blocks (PRBs) are allocated to carry Downlink Control Information (DCI). In step 1002, the base station determines a set of candidate narrowband physical downlink control channels (NB-PDCCHs) within the PRB. Each candidate NB-PDCCH is associated with a set of narrowband control channel elements (NCCEs) to potentially carry DCI. In step 1003, the base station maps a plurality of resource elements (REs) to each NCCE based on the RE to NCCE mapping rules. In step 1004, if the DCI is for the UE, the base station is transmitting to The DCI is encoded on a set of NCCEs of the UE.

Although the invention has been described in connection with certain specific embodiments for purposes of teaching, the invention is not limited thereto. Therefore, various modifications, adaptations and combinations of the various features of the described embodiments can be made without departing from the scope of the invention as set forth in the appended claims. The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

Claims (17)

A method for decoding a narrowband entity downlink control channel for a narrowband IoT device, the decoding method of the narrowband entity downlink control channel includes: receiving a control signal, and determining, by using the control signal, a plurality of received physical resource blocks And the plurality of physical resource blocks carry downlink control information; determining a set of candidate narrowband physical downlink control channels in the physical resource block, wherein each narrowband entity downlink control channel is used for a narrowband entity downlink A set of narrowband control channel elements transmitted by the control channel are associated; a plurality of resource elements are collected for each narrowband control channel element, wherein each narrowband control channel element consists of a plurality of resource elements based on narrowband control channel elements to resource element demapping rules Composed; one of the physical resource blocks is allocated to a narrowband physical downlink control channel having two narrowband control channel elements, wherein a first narrowband control channel element of the physical resource block is mapped to a first part of the physical resource block a plurality of resource elements of a plurality of consecutive subcarriers, And wherein a second narrowband control channel element of the physical resource block is mapped to a plurality of resource elements of a second plurality of consecutive subcarriers belonging to the physical resource block; and a downlink mapped to the collected plurality of resource elements The link control information is decoded. A method of decoding a narrowband entity downlink control channel according to claim 1, wherein the resource element collected for each narrowband control channel element is allocated in a physical contiguous radio resource block in addition to the narrowband entity The downlink control channel demodulates a plurality of consecutive resource elements on the entity other than the resource elements of the reference signal transmission. The method for decoding a narrowband entity downlink control channel according to claim 2, wherein the narrowband entity downlink control channel demodulation reference signal is a cell specific reference signal. A method for decoding a narrowband physical downlink control channel according to claim 1, wherein the user equipment transmits a single narrowband control channel in each narrowband entity downlink control channel. The downlink control information is decoded in the element. The decoding method of the narrowband entity downlink control channel of claim 1, wherein the user equipment decodes the downlink control in a plurality of narrowband control channel elements transmitted by each narrowband entity downlink control channel News. The method for decoding a narrowband entity downlink control channel according to claim 1, wherein the control signal defines a user equipment search space for the plurality of physical resource blocks carrying the downlink control information. A user equipment, comprising: a receiver, receiving a control signal to determine a plurality of received physical resource blocks, the plurality of physical resource blocks carrying downlink control information in a cellular network; a controller determining the a set of candidate narrowband entity downlink control channels within an entity resource block, wherein each narrowband entity downlink control channel is associated with a set of narrowband control channel elements for narrowband physical downlink control channel transmission; a collector Collecting a plurality of resource elements for each narrowband control channel element, wherein each narrowband control channel element is composed of a plurality of resource elements by a narrowband control channel element to a resource element demapping rule; wherein an entity resource block is assigned to have a narrowband physical downlink control channel of two narrowband control channel elements, wherein a first narrowband control channel element of the physical resource block is mapped to a plurality of resources of a first plurality of consecutive subcarriers belonging to the physical resource block An element, and wherein a second narrowband control channel element of the physical resource block is The physical resource blocks belonging to irradiated a second plurality of consecutive subcarriers plurality of resource elements; and a decoder, mapped to a plurality of resource elements of the downlink control information collected. The user equipment of claim 7, wherein the plurality of resource elements collected for each narrowband control channel element are in a physical contiguous radio resource block except for being allocated for a narrowband entity downlink control channel Decentralized reference signal transmission of elements other than resource elements consecutive Resource element. The user equipment of claim 8, wherein the narrowband entity downlink control channel demodulation reference signal is a cell specific reference signal. The user equipment of claim 7, wherein the user equipment decodes the downlink control information in a single narrowband control channel element transmitted by each narrowband entity downlink control channel. The user equipment of claim 7, wherein the user equipment decodes the downlink control information in a plurality of narrowband control channel elements transmitted by each narrowband entity downlink control channel. The user equipment of claim 7, wherein the control signal defines a user equipment search space for the plurality of physical resource blocks carrying the downlink control information. A method for encoding a narrowband entity downlink control channel for a network device, the encoding method of the narrowband entity downlink control channel includes: transmitting a control signal, wherein the network device allocates a set of physical resource blocks to carry a downlink Channel control information; determining a set of candidate narrowband physical downlink control channels within the physical resource block, wherein each narrowband entity downlink control channel is associated with a set of narrowband control channel elements to potentially carry the downlink control Information; mapping a plurality of resource elements to each narrowband control channel element based on a mapping rule of a resource element to a narrowband control channel element; one of the physical resource blocks is assigned to a narrowband entity downlink control having two narrowband control channel elements a channel, wherein a first narrowband control channel element of the physical resource block is mapped to a resource element of a first plurality of consecutive subcarriers belonging to the physical resource block, and wherein a second narrowband control channel element of the physical resource block Is mapped to a second plurality of contigs belonging to the entity resource block Resource element wave; and If the downlink control information is for the user equipment, the downlink control information is encoded on the set of narrowband control channel elements for transmission to the user equipment. The encoding method of the narrowband entity downlink control channel of claim 13, wherein the downlink control information is carried in a single narrowband control channel element transmitted by each narrowband entity downlink control channel. The encoding method of the narrowband entity downlink control channel of claim 13, wherein the downlink control information is carried in a plurality of narrowband control channel elements transmitted by each narrowband entity downlink control channel. The encoding method of the narrowband entity downlink control channel of claim 13, wherein the control signal defines a user equipment search space for the plurality of physical resource blocks carrying the downlink control information. The encoding method of the narrowband entity downlink control channel of claim 16, wherein the user equipment search space is an aggregation level of the narrowband control channel element, and is used for narrowband entity downlink control channel transmission time interval repetition. The number of repetitions, as well as a plurality of candidate narrowband entity downlink control channels, are defined.