This application relates to methods for configuring and activating or deactivating a device-to-device discovery signal.
Proximity-based applications and services represent a fast growing social and technological trend that may have a major impact on the evolution of cellular wireless/mobile broadband technologies. These services are based on the awareness that at least two devices or two users are close to each other and, thus, may be able to directly communicate with each other.
Proximity-based applications include social networking, mobile commerce, advertisement, gaming, etc. These services and applications stimulate the design and development of a new type of device-to-device (D2D) communication that ideally are to be seamlessly integrated into current and next generation mobile broadband networks such as LTE (short for long-term evolution) and LTE-advanced. By leveraging direct connectivity between two devices in the network, D2D communication would enable machines to communicate directly with one another.
The existing mobile broadband networks are designed to optimize performance mainly for network-based communications and thus are not optimized for D2D-specific requirements. For instance, they do not support the establishment of direct links between two devices. The efficient support and seamless integration of D2D communication in current and future mobile broadband technologies requires enhancements or modifications across different layers, e.g., physical (PHY) and MAC layers, in order to optimally address the future D2D demands, meet performance requirements, and overcome technical challenges.
The foregoing aspects and many of the attendant advantages of this document will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts throughout the various views, unless otherwise specified.
In accordance with the embodiments described herein, a method to transmit and receive a device-to-device (D2D) discovery signal is disclosed. The D2D discovery signal method operates using currently defined discovery signals as well as novel discovery signals, such as discovery signals employing a PUCCH-based uplink signal, an SRS-based demodulation and reference signal, or a single tone-based beacon signal. Under the D2D discovery signal method, an enhanced base station (eNB) configures the D2D discovery signal to both the transmitter (TX) user equipment (UE) and the receiver (RX) UE, then activates the D2D discovery signal to the TX and RX UEs, such that D2D signal transmission can thereafter occur from either the eNB or the TX UE, and monitored by the RX UE. Once the eNB deactivates the D2D discovery signal, D2D transmissions between UEs cease. Transmissions to configure, activate, and deactivate the D2D discovery signal can be unicast, multicast, or broadcast.
In the following detailed description, reference is made to the accompanying drawings, which show by way of illustration specific embodiments in which the subject matter described herein may be practiced. However, it is to be understood that other embodiments will become apparent to those of ordinary skill in the art upon reading this disclosure. The following detailed description is, therefore, not to be construed in a limiting sense, as the scope of the subject matter is defined by the claims.
The wireless neighborhood 100 consists of five D2D clusters 40A-40E (collectively, “D2D clusters 40”). The first D2D cluster 40A includes the D2D coordinator UE 50B along with two regular UEs 50 forming a D2D unicast link between UE 50D and UE 50E. The D2D coordinator UE 50B can further communicate with a pico/home eNB 20B.
The second D2D cluster 40B includes D2D coordinator 50D also communicating with pico/home eNB 20B. A D2D unicast link is formed between UEs 50F and 50G.
The third D2D cluster 40C features D2D coordinator 50C, communicating with macro eNB 20A, and D2D broadcast links between the D2D coordinator and each of UEs 50H and 50J. The transmissions in the D2D cluster 40C represent D2D broadcasting operations, in which the D2D coordinator broadcasts to both the UE 50H and the UE 50J simultaneously.
The fourth D2D cluster 40D features D2D coordinator 50A communicating with pico/home eNB 20C, and communicating with UE 50K, which then communicates with UE 50L. The operations taking place in the fourth D2D cluster 40D are known as a multi-hop configuration.
The fifth D2D cluster 40E does not include a D2D coordinator. Instead, UE 50N communicates directly with macro eNB 20A and a mesh configuration is established between UEs 50M, 50N, 50O, and 50P such that each is able to communicate with other UEs in the D2D cluster 50E.
In addition to the five clusters 40, the wireless neighborhood 100 features two rogue UEs 50T and 50S, each of which communicate directly with the macro eNB 20A.
D2D users may operate in a co-existing mode and reuse the spectrum with other cellular users (as shown in
The proximity sensing methods may be implemented by the network through monitoring the UE attachment/association to a particular cell or using location-based services and protocols. In addition to these traditional methods, new proximity-based functionality may be added to the functions of the D2D coordinator. For instance, a special device discovery zone may be allocated in the D2D transmission region where device discovery signaling is used to assist in D2D cluster organization and D2D link establishment. A special discovery signal transmission interval can be introduced in the D2D transmission region for that purpose. Additionally, proximity sensing may be based on D2D link quality measurements.
As a discovery signal, the existing signal or newly defined signal can be used.
The signal exchanges of
The signal exchanges in
The signal transmissions depicted in
Following configuration, the eNB activates the D2D discovery signal for transmission. In
As used herein, the term, “activate,” means the D2D discovery signal from a UE may be transmitted and/or that by another UE may be monitored (received). Likewise, the term, “deactivate,” means the transmission and/or reception of the D2D discovery signal may be terminated. Usually, the latter, deactivation, occurs to save power consumption of the UE 50.
Once the configuration and activation has been completed, D2D transmissions between UEs 50 are possible. D2D transmissions may also come from the eNBs 20. In
A given UE 50 may be configured for half-duplex mode. This would mean that the UE 50 is able to transmit or receive (monitor), but would not be able to simultaneoulsy transmit and receive. Or, the UE 50 may be an advanced transceiver having full-duplex capability to both transmit and receive simultaneously. One objective of D2D transmissions is for transmissions to take place directly between UEs 50. Thus, where UE 50W is configured for half-duplex mode, the transmission in step 7, from eNB 20 to UE 50W would not take place since UE 50W was configured for transmission (step 3).
In some embodiments, the eNB 20 indicates which UEs are for transmission and which are for reception (monitoring) in a single step, such as by defining the bits where each is mapped to each UE in the wireless neighborhood, whereby a “0” in the bit location indicates that the UE mapped to that bit is a transmitter/receiver and a “1” in the bit location indicates the UE mapped to that bit is a receiver/transmitter. The bit fields may be conveyed in the format of L1 control signaling (e.g. PDCCH or EPDCCH). In another embodiment, two different fields are used, one to indicate those UEs performing D2D transmission operations and another to indicate those UEs monitoring D2D transmissions.
Radio network temporary identifiers (RNTIs) are used to scramble the code words, in the physical channel, prior to transmission on the physical channel. This scrambling process in the physical layer happens before modulation.
The Radio Network Temporary Identifier (RNTI) is a generic form of an identifier for a UE mainly when RRC connection exists. Some RNTIs, such as MBMS RNTI (M-RNTI), Paging RNTI (P-RNTI), and System Information RNTI (SI-RNTI), do not require an RRC connection and thus they have their own fixed values for each RNTI. For instance, in hexa-decimal expressions, M-RNTI, P-RNTI, and SI-RNTI may have the fixed values of FFFD, FFFE, and FFFF, respectively. RNTIs of several different types are used: Semi-Persistent Scheduling RNTI (SPS-RNTI), Cell RNTI (C-RNTI), MBMS RNTI (M-RNTI), Temporarily C-RNTI (TC-RNTI), Paging RNTI (P-RNTI), Random Access RNTI (RA-RNTI), Transmit Power Control-Physical Uplink Control Channel-RNTI (TPC-PUCCH-RNTI), and Transmit Power Control-Physical Uplink Shared Channel-RNTI (TPC-PUSCH-RNTI), to name a few. In this regard, D-RNTI may be newly defined and can represent a D2D group identifier used in D2D communications.
According to the 3GPP 36.321 specification, the C-RNTI is a 16-bit numeric value that is is part of the MAC logical channel group ID field (LCG ID). The C-RNTI thus defines unambiguously which data sent in a downlink direction within a particular long-term evolution (LTE) cell belongs to a particular subscriber. Thus, C-RNTI is used for cell tracing. The C-RNTI comes in three different flavors: temp C-RNTI, semi-persistent scheduling C-RNTI, and C-RNTI. A newly defined RNTI for D2D discovery and communication is denoted D-RNTI. Further, a D-RNTI may represent a group ID comprising multiple UEs.
In some embodiments, the UE identifiers may be represented using C-RNTIs and D-RNTIs, with the C-RNTI indicating an individual UE and D-RNTI indicating a group consisting of multiple UEs. Table 1 provides four different scenarios for defining two different UE IDs using C-RNTI and D-RNTI, according to some embodiments. Here, “UE#0” is meant to indicate a UE or a UE within a D2D group set up for D2D transmission/monitoring while “UE#1” indicates a UE or a UE within a D2D group set up for D2D monitoring/transmission, respectively. In the first choice, only C-RNTI, C-RNTI#0 for UE#0 and C-RNTI#1 for UE#1, is used. Since C-RNTI references a single UE 50, the first choice configures one UE for transmission and one UE for monitoring. In the fourth choice, only D-RNTI, D-RNTI#0 for UE#0 and D-RNTI#1 for UE#1, is used. Since D-RNTI references a D2D group of UEs, the fourth choice configures a UE 50 within a D2D group for transmission and another UE within another D2D group for reception.
In a special case, D-RNTI#0 may be identical to D-RNTI#1. This case can configure a UE 50 within a D2D group for transmission and another UE within the D2D group for reception. The second and third choices mix up use of the C-RNTI and D-RNTI, and thus envision single-transmitter-multiple-receiver and single-receiver-multiple-transmitter scenarios.
Thus, the operations depicted in the signaling diagram of
Further, for the above embodiment, the following procedures may be taken into account:
The eNB may configure D2D discovery signal to one or more UEs.
The eNB may configure one or multiple RNTIs to the UEs.
The eNB may activate the D2D discovery signal to one or more UEs 50.
In a first embodiment (
In another embodiment, as illustrated in
In still another embodiment, as illustrated in
In the first example, groups of UEs 50 will be transmitters and groups of UEs will be monitors. Thus, D-RNTI, the temporary identifier useful for D2D group transmissions, is used. As illustrated in
This example is simply the opposite of example 1, in that the programming of transmitters and monitors is reversed. As illustrated in
Where a single transmitter or a single receiver are to be programmed, the temporary identifier, C-RNTI, can be used. As illustrated in
This example is simply the opposite of example 3, in that the programming of the single transmitter and the single monitor are reversed. As illustrated in
This example is for multiple transmitters but a single receiver. As illustrated in
This example is for a single transmitter but multiple receivers. As illustrated in
In other embodiments, the activation/deactivation of D2D discovery signal may be done by group indication.
In
A DCI with CRC masked by a first D-RNTI indicates which UEs 50 are to be transmitters (block 1108) and which UEs are to be monitors of the D2D discovery signal in a given configuration.
In
Each bit position may be occupied by each UE within a D2D group. For example, the D2D group with D-RNTI#0 from
Each device includes an antenna 154, a front-end 132, a radio 136, a baseband digital signal processor (DSP) 138, and a medium access controller (MAC) 130. Although both devices have the hardware shown in each device, the eNB 20 is shown having a power amplifier 146 in its front-end 132 while the UE 50 includes a low noise amplifier 148 in its front-end. The eNB 50 includes a digital-to-analog converter (DAC) 134 while the UE 50 includes an analog-to-digital converter (ADC) 142. The UE 50 may be virtually any wireless device, such as a laptop computer, a cellular phone, or other wireless system, and may operate as a transmitter (transmit mode) or as a receiver (receive mode).
The MAC 130 includes an embedded central processing unit (CPU) 124 and a data memory 120, such that the D2D discovery signal method 200, some portion of which is software-based, in some embodiments, may be loaded into the memory and executed by the CPU. The depiction of
The MAC 130 interfaces with logic devices that are commonly found in transmitters and receivers: the front-end 132, the DAC 134, the ADC 142, the radio 136, and the DSP 138. The devices 132, 134, 136, 138, and 142 are also known herein as target modules. The target modules, as well as the logic devices within the MAC 130, may consist of hardware, software, or a combination of hardware and software components.
The target modules are commonly found in most transmitters and receivers. The FE 132 is connected to the antenna 154, and includes a power amplifier (PA) (for the transmitter), a low noise amplifier (LNA) (for the receiver), and an antenna switch (not shown), for switching between transmitter and receiver modes. The DAC 134 is used to convert the digital signal coming from the DSP 138 to an analog signal prior to transmission via the radio (transmitter); conversely, the ADC 142 is used to convert the analog signal coming from the radio to a digital signal before processing by the DSP 138 (receiver). At the eNB 20, the radio 136 transfers the signal from base-band to the carrier frequency; at the UE 50, the radio 136 transfers the signal from carrier frequency to base-band. At the UE 50, the DSP 138 demodulates the OFDM signal from the ADC 142, for processing by the MAC 130. At the eNB 20, the DSP 138 modulates the MAC data into an OFDM signal in base-band frequency, and sends the resulting signal to the DAC 134.
A typical transmit operation occurs as follows: at the eNB 20, the MAC 130 sends a packet to the DSP 138. The DSP 138 converts the packet into a digital OFDM signal and sends it to the DAC 134. The DAC 134 converts the signal into an analog signal, and sends the signal to the radio 136. The radio 136 modulates the base-band signal to the carrier frequency and sends the signal to the power amplifier 146 of the front-end 132, which amplifies the signal to be suitable for over-air transmission via the antenna 154.
At the UE 50, the signal is received by the antenna 154. The weak analog signal is received into the low noise amplifier 148 of the front-end 132, sending the amplified analog signal to the radio 136, which filters the signal according to the selected frequency band and demodulates the carrier frequency signal into a base-band signal. The radio 136 sends the analog signal to the ADC 142, which converts the analog signal to a digital signal, suitable for processing by the DSP 138. The DSP 138 demodulates the OFDM signal and converts the signal to MAC 130 packet bytes. Other operations, such as encryption and decryption of the packets, are not shown. Where the transmission is successful, the packet received by the MAC 130 in the UE 50 is the same as the packet transmitted by the MAC 130 in the eNB 20.
In other embodiments, as depicted in
While the application has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of the invention.
This application claims priority to U.S. Provisional Patent Application Number 61/734,323, filed on Dec. 6, 2012.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2013/062485 | 9/27/2013 | WO | 00 | 12/13/2013 |
Number | Date | Country | |
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61734323 | Dec 2012 | US |