Patent Publication Number: US-10791515-B2

Title: Physical layer protocol and subframe structure for wearable user equipment devices

Description:
RELATED APPLICATION 
     This application is a national stage filing under U.S.C. § 371 of International Patent Application No. PCT/US2016/039521, filed Jun. 27, 2016, which claims benefit of U.S. Provisional Patent Application No. 62/300,332, filed Feb. 26, 2016, each of which is hereby incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     This disclosure relates generally to communication systems supporting wearable user equipment (UE) devices, and, more specifically, to an interface layer-one (L1) procedure and radio frame and subframe structures for allocating physical resources between wearable user equipment (wUE) devices (or simply, wUEs) and network UEs (nUEs). 
     BACKGROUND INFORMATION 
     Some devices currently use Bluetooth®, Bluetooth® Low Energy (Bluetooth® LE, BLE, marketed as Bluetooth® Smart), or other short-range wireless personal area network technologies for exchanging data over short distances. Bluetooth®, however, is limited to a three megabit per second (Mbit/s) over-the-air data rate and exhibits poor performance in ultra-dense deployments characterized by many devices communicating in a relatively small area (e.g., a subway). Other wireless local area networking (WLAN) technologies, such as Wi-Fi®, consume relatively high amounts of power that may not be available in mobile devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a system architecture for supporting wUEs in communication with a network UE (nUE) through an Xu-a air interface. 
         FIG. 2  is a state transition diagram showing operational states and state transitions of a wUE and an nUE sharing an Xu interface. 
         FIG. 3  is a block diagram showing a radio-frame, subframe, and subchannel structure for uplink (UL) and downlink (DL) communications through an Xu-a air interface. 
         FIG. 4  is a block diagram of a subframe structure, according to a (first) option A embodiment. 
         FIG. 5  is a block diagram of a subframe structure, according to a (second) option B embodiment. 
         FIG. 6  is a block diagram of a subframe structure, according to a (third) option C embodiment. 
         FIG. 7  is a block diagram of a subframe structure, according to a (fourth) option D embodiment. 
         FIG. 8  is a sequence diagram of an L1 procedure. 
         FIG. 9  is a block diagram of paging and discovery region allocation in a subchannel. 
         FIG. 10  is a block diagram showing discovery content message transmission. 
         FIG. 11  is a block diagram showing a discovery content message broadcasting subframe. 
         FIG. 12  is a sequence diagram of a discovery procedure. 
         FIG. 13  is a block diagram illustrating electronic device circuitry that may be UE circuitry, evolved universal terrestrial access network (EUTRAN) Node B (evolved Node B, eNodeB, or eNB) circuitry, network node circuitry, or other types of circuitry, according to one embodiment. 
         FIG. 14  is a block diagram illustrating components of a UE device according to one embodiment. 
         FIG. 15  is a block diagram illustrating components according to some embodiments. 
     
    
    
     Aspects and advantages will be apparent from the following detailed description of embodiments, which proceeds with reference to the accompanying drawings. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIG. 1  shows a communication system  100  for supporting wUEs. Entities of the system  100  include an nUE  110  having a full infrastructure network-access protocol stack (i.e., for full control- and user-plane functions); several wUEs  120  (e.g.,  120   a ,  120   b , and  120   c ) lacking standalone network-access connections but instead achieving network-access through, and coordinated by, the nUE  110 ; a EUTRAN Node B (or more generally, a base station)  130 ; and an evolved packet core (EPC)  140 . The nUE  110  and one or more of the wUEs  120  mutually authenticate to form a personal area network (PAN). 
     Air interfaces between the entities include an S1 interface  145  between the EPC  140  and the eNB  130 ; a Uu-p interface  150  between the nUE  110  and the eNB  130 ; a (higher power-demand) Uu-w interface  160   a  between the wUE  120   a  and the eNB  130  (similar Uu-w interfaces are not shown for the wUE  120   b  and the wUE  120   c ); Xu-a interfaces  170  between the nUE  110  and the wUE  120   a  and the wUE  120   b ; and an Xu-b interface  180  between the wUE  120   b  and the wUE  120   c  (other Xu-b interfaces are not shown). In general, the Xu-a interfaces provide intra-PAN air interfaces between an nUE and associated wUEs, and the Xu-b interfaces provide intra-PAN air interfaces among wUEs, but design principles described herein may apply to either of the Xu-a or Xu-b interfaces (generally referred to as Xu interfaces). 
     The described Xu interfaces and associated L1 procedures are designed for energy-efficient operation and to meet other performance specifications and characteristics of ultra-dense deployments. For example, with respected to the Xu-a and Xu-b interfaces, a typical transmission power may be of 0 dBm or less, and the power consumption of the baseband modem constitutes a primary portion of total power consumption. To provide for power-efficient baseband operation and other design considerations, the following aspects are contemplated in the design of the Xu interfaces and L1 procedures: low baseband computation complexity; a baseband or core processor that is placed in an idle state as much as possible; ultra-dense deployment scenarios; uplink (UL) and downlink (DL) resource acquisition and utilization fairness among various UEs; and scalability from small to large networks. 
     Based on the aforementioned design considerations, this disclosure describes frame structures and L1 procedures suitable for the Xu interface(s). Some features of the design are summarized as follows. 
     The design features a common synchronization source for nUEs and wUEs within one synchronized cluster (also called a synchronization cluster). A synchronization cluster may have multiple PANs. For example, a wUE may be in range of a first nUE but out of range of a second nUE, but the nUEs are still synchronized because they can hear each other&#39;s broadcast channel. Accordingly, all the nUEs and wUEs within a cluster are synchronized through a common synchronization channel. In other words, all the nUEs are broadcasting the same synchronization signal (SS), which may comprise a sequence. And, in some embodiments deployed within a base station coverage region, the base station optionally maintains synchronization by providing, for example, primary/secondary synchronization signals (PSS/SSS). Because there is a common synchronization, the design may maintain a radio frame boundary aligned among the PANs for reduced collision avoidance. 
     The design can be operated in both licensed and unlicensed bands. For example, in the licensed band resources may be allocated by a base station or the PAN may share resources with a licensed system. In the unlicensed band, the PAN may share resources with an unlicensed system. 
     The design affords support of various system bandwidth values comprising a flexible number of subchannels. 
     The design also allows for dynamic configuration of a DL/UL ratio of subframes in a time-division duplex (TDD) radio frame. Accordingly, the nUE configures the DL/UL operation of each PAN by providing an indication to the wUEs through a physical control channel. The physical control channels are channels in the first two or three symbols of each subframe. For example, a scheduling assignment (SA) channel and an SA response (SAR) channel (e.g.,  FIG. 5 ) are physical control channels. 
     The design includes a self-contained frame structure. In other words, data is transmitted in one portion of a subframe and feedback, such as an acknowledgement (ACK) or negative ACK (NACK), is provided during another portion of the same subframe. Thus, each subframe is self-contained because it encompasses both communication (e.g., downlink) and feedback (e.g., uplink) periods at different times in the subframe. Also, although each subframe includes uplink and downlink periods, the subframes are referred to as UL or DL subframes because DL subframes include physical resources for transmission of DL data from an nUE to a wUE and UL subframes include physical resources for transmission of UL data from a wUE to an nUE. 
     The design includes contention-based inter-PAN resource coordination for scalability. Resource allocation of each PAN is done by handshaking—i.e., no central resource allocation is used in some embodiments. Also, under the contention-based embodiments, there is an automatic backoff timer for obtaining resources after collision in, for example, an ultra-dense deployment scenario. 
     Another aspect of the design includes allowing a base station to coordinate the resource allocation when the nUE or its associated PAN overlaps with coverage of the base station. In other words, the base station can help assign resources to one or more PANs. And the resources allocated to each PAN might be selected by the base station to avoid collisions. 
     The design considers autonomous fairness control in which an nUE performs smart scheduling by allowing each wUE some access to the resources. 
     In a dense scenario, there is an increased likelihood of collision between wUEs requesting resources. Accordingly, the design includes a backoff procedure for reducing subsequent collisions. 
     The design considers a rapid transition between active and idle/power saving states for power savings. 
     The proposed protocol can be generally applied in mobile cell scenarios including personal area network, home area network, vehicle-to-vehicle (V2V), mobile relay, or other scenarios. 
     Identifiers 
     Initially, the following Table 1 includes a list of identifiers (IDs) and describes the associated information provided by these IDs, such as media access control (MAC) addresses. These IDs are referred to in subsequent tables and paragraphs of this disclosure. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 IDs 
                 Description or Function 
               
               
                   
               
             
            
               
                 nUE MAC 
                 Unique address for nUE 
               
               
                 address 
                   
               
               
                 wUE MAC 
                 Unique address for wUE 
               
               
                 address 
                   
               
               
                 nUE temporary 
                 This ID is generated from nUE MAC address and is 
               
               
                 short ID (also  
                 used to identify the nUE during intra-PAN 
               
               
                 called a short ID) 
                 communication 
               
               
                 wUE temporary 
                 This ID is generated from wUE MAC address and is 
               
               
                 short ID (also  
                 used to identify the wUE during intra-PAN 
               
               
                 called a short ID) 
                 communication 
               
               
                 Discovery ID 
                 A pool of discovery IDs is defined. These are used for 
               
               
                   
                 broadcasting discovery content messages. 
               
               
                 Random Access 
                 This ID is generated from nUE short ID and is used by 
               
               
                 (RA)-ID 
                 wUE during random access to the nUE 
               
               
                   
               
            
           
         
       
     
     States of Operation 
       FIG. 2  describes four operation states  200  and the transition between the states described as follows. 
     In a peer discovery state  210 , an nUE (e.g., the nUE  110 ) and an accessible wUE (e.g., the wUE  120   a ) send discovery signals to be mutually discovered. The discovery procedure is described later with reference to  FIG. 12 . 
     In a communication state  220 , there is active (on-going) time-division duplex (TDD) traffic exchanged between the nUE and the wUE. 
     In an idle state  230 , the wUE does not have an active exchange of traffic, but the context of the connection between the nUE and the wUE is still maintained at the wUE. The wUE periodically wakes up to monitor paging. 
     In a power saving state  240 , the wUE releases the context of the connection between the wUE and the nUE. The nUE may then enter a power-saving mode (PSM) after all of its associated wUEs are in the PSM. Once in PSM, the nUE and wUE may re-establish the connection via peer discovery. 
     Frame Structure 
       FIG. 3  is a hierarchical depiction of radio frame structure  300 , a TDD-based subframe structure  310  of the radio frame  300 , a system bandwidth  320  allocated in subchannels  330 , and TDD-based channels  340  allocated in the subchannels  330 . 
     The radio frame  300  shows 10 subframes, but the number of subframes within each frame can be greater or less than 10. Among the subframes within each frame, at least one subframe is preconfigured as a DL subframe.  FIG. 3 , for example, shows subframe #0 is allocated as the DL subframe, though other allocations are possible. Other subframes can be flexibly configured as DL or UL subframes, which is indicated in  FIG. 3  by the “DL/UL” notation. As an aside, DL refers to a transmission direction from nUE to wUE, and UL refers to a transmission direction from wUE to nUE. The DL and UL transmission can be dynamically scheduled in each PAN. In each subframe, some of the PANs can transmit in their acquired resource allocations in the UL direction while some of the PANs can transmit in their acquired resource allocations in the DL direction. 
     The smallest unit of physical resources available in the frame is referred to as a resource element (RE) of one symbol and one subcarrier. A block (in time and frequency) of adjacent REs form a physical resource block (PRB). Two temporally adjacent PRBs are referred to as a pair of PRBs. In some embodiments, a subchannel has a subchannel bandwidth corresponding to multiple pairs of PRBs. The subchannel bandwidth is then partitioned according to a physical resource assignment (PRA) allocated for communications between an nUE and an associated wUE. One example of resources available in a frame structure is set forth in Table 2. 
     
       
         
           
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Name 
                 Size 
               
               
                   
               
             
            
               
                 RE 
                 1 subcarrier × 1 symbol 
               
               
                 PRB 
                 84 REs = 
               
               
                   
                 12 subcarriers × 7 symbols 
               
               
                 Subchannel 
                 6 pairs of PRBs = 
               
               
                   
                 (6 × 12 subcarriers) × (2 × 7 symbols) 
               
               
                 PRA 
                 Aggregation levels: 1 PRB, 2 PRB, 3 PRB, or 6 PRB 
               
               
                   
               
            
           
         
       
     
     Each nUE determines an aggregation level of the PRA. The aggregation level of the PRA of each nUE is consistent throughout one subframe. An associated wUE needs to do blind detection on one subchannel to try different aggregation levels. In general, blind detection is used when multiple UEs in a coverage region share a common resource. Accordingly, each UE blindly detects in that resource its own control or data information, e.g., decoding all of the information to obtain the information meant for the particular wUE. After detecting the aggregation level, the wUE can employ the same PRA aggregation level for detecting the other channels. 
       FIG. 3  shows a centrally located subchannel used for an SS  350 , a broadcast channel (BCH)  360 , and a paging and discovery channel  370  shown in greater detail in  FIG. 9 . Other subchannels show an example of a subframe structure having an internal TDD channel allocation—defined by multiple guard periods (GPs)—shown in greater detail in  FIG. 6 , but any of the following options described with reference to  FIGS. 4-7  (or combinations thereof) could be used for the TDD resource allocation shown in  FIG. 3 . 
       FIG. 4  shows an annotated subframe structure  400  referred to as option A. Descriptions of the physical channels in the subframe structure  400  are set forth in Table 3. The contents of the physical channels and the number of bits carried therein are listed as examples. Also, guard period (GP)  2  is optional when UL traffic is scheduled in the data channel. 
     
       
         
           
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Channel 
                 Content 
               
               
                   
               
             
            
               
                 Scheduling 
                 DL/UL indication (1 bit) + nUE Tx power per RE in the  
               
               
                 Assignment  
                 PRA (6 bits) + DL modulation coding scheme (MCS)  
               
               
                 (SA) (i.e., DL) 
                 (4 bits) + cyclic redundancy check (CRC) (5 bits) 
               
               
                   
                 Scrambled by wUE short ID (e.g., using an XOR  
               
               
                   
                 operation) 
               
               
                 SA Response  
                 DL: DL MCS (4 bits) + DL power headroom (PHR)  
               
               
                 (SAR) (i.e., UL) 
                 (5 bits) + CRC (5 bits) 
               
               
                   
                 UL: UL MCS (4 bits) + DL PHR (5 bits) + CRC (5 bits) 
               
               
                   
                 Scrambled by wUE short ID 
               
               
                 RA 
                 Option 1: buffer status report (BSR) (5 bits) + wUE  
               
               
                 (i.e., UL) 
                 short ID (9 bits) + CRC (5 bits) (no information  
               
               
                   
                 bit-level scramble)  
               
               
                   
                 Option 2: BSR (5 bits) + CRC (5 bits) 
               
               
                   
                 (scrambled by wUE short ID), nUE may try all 
               
               
                   
                 the wUE short IDs 
               
               
                 Data 
                   
               
               
                 (i.e., DL/UL) 
                   
               
               
                 ACK/NACK 
                 wUE feedback: ACK/NACK (4 bits) (repetition) + BSR  
               
               
                 (i.e., DL/UL) 
                 (5 bits) + CRC (5 bits) 
               
               
                   
                 nUE feedback: ACK/NACK (9 bits) (repetition) + CRC 
               
               
                   
                 (5 bits) 
               
               
                   
                 Scrambled by wUE short ID 
               
               
                   
               
            
           
         
       
     
     Option A has less overhead because it has two control channels instead of three or more. In case of traffic depending on low latency transmission, the transmission power of the SA and SAR channels can be boosted so that the traffic can have a higher chance of getting the channel and can be more reliably delivered. 
       FIG. 5  shows an annotated subframe structure  500  referred to as option B. Descriptions of the physical channels in the subframe structure  500  are set forth in Table 4. The contents of the physical channels and the number of bits carried are listed as examples. GP 2 is optional when DL traffic is scheduled in the data channel. 
     
       
         
           
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                 Channel 
                 Content 
               
               
                   
               
             
            
               
                 RA 
                 wUE Tx power per RE (6 bits) + wUE short 
               
               
                 (i.e., UL) 
                 ID (9 bits) + CRC (5 bits) 
               
               
                   
                 Not scrambled in information bits level 
               
               
                 RA Response (RAR) 
                 DL/UL indication (1 bit) + MCS 
               
               
                 (i.e., DL) 
                 (4 bits) + UL PHR (5 bits) + CRC (5 bits) 
               
               
                   
                 If no corresponding RA, UL PHR is all zero 
               
               
                   
                 Scrambled by wUE short ID 
               
               
                 ACK/NACK 
                 wUE feedback: ACK/NACK (4 bits) 
               
               
                 (i.e., DL/UL) and DL 
                 (repetition) + BSR (5 bits) + CRC (5 bits) 
               
               
                 Traffic Indicator 
                 nUW feedback: ACK/NACK (9 bits) 
               
               
                   
                 (repetition) + CRC (5 bits) 
               
               
                   
                 Scrambled by wUE short ID 
               
               
                 Data 
                   
               
               
                 (i.e., DL/UL) 
               
               
                   
               
            
           
         
       
     
     Option B operation is wUE centric because the wUE initiates resource acquisition. This option does not use blind detection at the wUE, and it also has less overhead because there are fewer control channels. In case of traffic depending on low latency transmission, the transmission power of the RA and RAR channels can be boosted so that the traffic can have a higher chance of getting the channel and can be more reliably delivered. 
       FIG. 6  shows an annotated subframe structure  600  referred to as option C. Descriptions of the physical channels in the subframe structure  600  are set forth in Table 5. The contents of the physical channels and the number of bits carried are listed as examples. GP 3 is optional when DL traffic is scheduled in the data channel. 
     
       
         
           
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                 Channel 
                 Content 
               
               
                   
               
             
            
               
                 SA 
                 wUE short ID (9 bits) + CRC (5 bits) 
               
               
                 (i.e., DL) 
                   
               
               
                 SAR 
                 DL PHR (4 bits) + CRC (5 bits) 
               
               
                 (i.e., UL) 
                 Scrambled by wUE short ID 
               
               
                 DL Control 
                 DL/UL indication (1 bit) + MCS (4 bits) + UL PHR 
               
               
                   
                 (4 bits) + CRC (5 bits) 
               
               
                 RA 
                 Option 1: BSR (5 bits) + wUE short ID (9 bits) + CRC (5 
               
               
                 (i.e., UL) 
                 bits) (no information bit level scramble) 
               
               
                   
                 Option 2: BSR (5 bits) + CRC (5 bits) (scrambled by 
               
               
                   
                 wUE short ID), nUE try all wUE short ID 
               
               
                 Data 
                   
               
               
                 (i.e., 
                   
               
               
                 DL/UL) 
                   
               
               
                 ACK/NACK 
                 wUE feedback: ACK/NACK (4 bits) (repetition) + BSR (5 
               
               
                 (i.e., 
                 bits) + CRC (5 bits) 
               
               
                 DL/UL) 
                 nUW feedback: ACK/NACK (9 bits) (repetition) + CRC (5 
               
               
                   
                 bits) 
               
               
                   
                 Scrambled by wUE short ID 
               
               
                   
               
            
           
         
       
     
     Option C can provide more accurate scheduling and less likelihood of collision, and is more robust to hidden node problems. However, the overhead is higher due to an increased number of control channels. There is also some blind detection performed at the wUE. 
     In case of traffic depending on low latency transmission, the transmission power of the SA, SAR, and DL control channels can be boosted so that the traffic can have a higher chance of getting the channel and can be more reliably delivered. 
       FIG. 7  shows an annotated subframe structure  700  referred to as option D. Descriptions of the physical channels in the subframe structure  700  are set forth in Table 6. The contents of the physical channels and the number of bits carried are listed as examples. GP 1 is optional when DL traffic is scheduled in the data channel. 
     
       
         
           
               
               
             
               
                 TABLE 6 
               
               
                   
               
               
                 Channel 
                 Contents 
               
               
                   
               
             
            
               
                 SA 
                 DL/UL indication (1 bit) + MCS (4 bits) + nUE Tx power  
               
               
                 channel 
                 per RE in the PRA (6 bits) + UL PHR (4 bits) + CRC (5 bits) 
               
               
                 (i.e., DL) 
                 Scrambled by wUE short ID 
               
               
                 RA 
                 Option 1: BSR (5 bits) + 9 bits wUE short mac id + CRC (5 
               
               
                 (i.e., UL) 
                 bits) (no information bit level scramble) 
               
               
                   
                 Option 2: BSR (5 bits) + CRC (5 bits) (scrambled by wUE 
               
               
                   
                 short ID), nUE try all wUE short ID 
               
               
                 Data 
                   
               
               
                 (i.e., 
                   
               
               
                 DL/UL) 
                   
               
               
                 ACK/NACK 
                 wUE feedback: indication of either ACK response to SA, or  
               
               
                 (i.e., 
                 to both SA and data channels (1 bit) + ACK/NACK (4 bits) 
               
               
                 DL/UL) 
                 (repetition) + BSR (5 bits) + DL PHR (4 bits) + CRC (5 bits) 
               
               
                   
                 nUW feedback: ACK/NACK (10 bits) (repetition) + UL 
               
               
                   
                 PHR + CRC (5 bits) 
               
               
                   
                 Scrambled by wUE short ID 
               
               
                   
               
            
           
         
       
     
     Option D will have less control and guard period overhead. However, this option does not have a handshake procedure for collision avoidance. The nUE will transmit DL traffic even if a collision happens. For traffic in the DL, after transmitting SA, the nUE will transmit DL data. The wUE feeds back ACK to indicate reception of SA and data. A separate ACK for indication of reception of SA is needed so that the reception error due to a collision and a data channel decoding error can be differentiated and consequently treated differently. For traffic in the UL, if the wUE fails to detect the SA, it will not transmit in the UL and the nUE will know the occurrence of a collision given no ACK feedback from the wUE. 
     In case of traffic depending on low latency transmission, the transmission power of the SA channel can be boosted so that the traffic can have a higher chance of getting the channel and can be more reliably delivered. 
     Numerology 
     Example numerologies are shown in Table 7. Option 1 follows conventional LTE subcarrier spacing. Options 2 and 3 have increased subcarrier spacing. To support the same maximum system bandwidth (e.g., 20 MHz), the fast Fourier transform (FFT) size of options 2 and 3 can be smaller and can reduce the implementation complexity. On the other hand, give the same number of subcarriers in the minimum system bandwidth, the minimum system bandwidth of options 2 and 3 would be larger than that of option 1. This could impact the SS design. Moreover, when using short subframe length in options 2 and 3, the physical (PHY) layer overhead (i.e., GP, scheduling assignment, control, feedback) could be high. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 7 
               
               
                   
               
               
                 Numerology 
                 Option 1 
                 Option 2 
                 Option 3 
               
               
                   
               
             
            
               
                 Subcarrier Spacing 
                 15 kHz 
                 60 kHz 
                 75 kHz 
               
               
                 Sampling rate 
                 30.72 MHz 
                 30.72 MHz 
                 38.4 MHz 
               
               
                 (1/Ts) 
                 (20 MHz, 2048-FFT) 
                 (20 MHz, 512-FFT) 
                 (20 MHz, 512-FFT) 
               
               
                   
                 1.92 MHz 
                 7.68 MHz 
                 9.6 MHz 
               
               
                   
                 (1.4 MHz, 128-FFT) 
                 (5 MHz, 128-FFT) 
                 (6 MHz, 128-FFT) 
               
               
                   
                   
                   
                 4.8 MHz 
               
               
                   
                   
                   
                 (2 MHz, 64-FFT) 
               
               
                 Number of 
                 1200 
                 320 
                 240 
               
               
                 Subcarriers 
                 72 
                 72 
                 72 
               
               
                   
                   
                   
                 24 
               
               
                 Cyclic Prefix (CP) 
                 16Ts = 0.5208 μs 
                 16Ts = 0.5208 μs 
                 20Ts = 0.5208 μs 
               
               
                 Length 
                   
                   
                   
               
               
                 Symbol Length 
                 (2048 + 16)Ts = 
                 (512 + 16)Ts = 
                 (512 + 20)Ts = 
               
               
                   
                 67.18 μs 
                 17.18 μs 
                 14.27 μs 
               
               
                 Number of 
                 14 
                 14 
                 14 
               
               
                 Symbols/Subframe 
                   
                 28 
                 35 
               
               
                   
                   
                 56 
                 70 
               
               
                 Subframe Length 
                 1 ms 
                 0.25 ms   
                 0.2 ms   
               
               
                   
                   
                 0.5 ms   
                 0.5 ms   
               
               
                   
                   
                 1 ms 
                 1 ms 
               
               
                 Frame Length 
                 10 ms  
                 2.5 ms   
                 2 ms 
               
               
                   
                   
                 5 ms 
                 5 ms 
               
               
                   
                   
                 10 ms  
                 10 ms  
               
               
                   
               
            
           
         
       
     
     L1 Procedure 
       FIG. 8  shows an L1 procedure  800 . An nUE  810  and a wUE  820  monitor the SS and system broadcasting signal from a synchronization source  830  (which may be a nearby nUE or a base station). If the nUE  810  or the wUE  820  cannot detect a synchronization signal, then the nUE  810  itself may become a synchronization source (the wUE  820  typically would not be a sync source unless it is triggered by users, i.e., when they seek to pair with another wUE). 
     After detecting synchronization and system information, the wUE  820  then discovers the nUE  810  via a discovery procedure (see, e.g.,  FIG. 12 ) including detecting a discovery ID message (see, e.g.,  FIG. 9 ) and receiving a discovery content message (see, e.g.,  FIGS. 10 and 11 ). 
     After discovering the desired nUE  810 , the wUE  820  performs a random access procedure to obtain resources from the nUE  810 . Upon successful detection of the random access signal from the wUE  820 , and when certain conditions are met (i.e., authentication and security and the load of the nUE  810  is not exceeded), the nUE  810  admits the wUE  820  and schedules communications. 
     In cases where the wUE  820  does not have traffic for a certain period, the wUE  820  may enter into an idle mode (described previously) in which the wUE  820  maintains system timing and periodically monitors paging. 
     When paged, the wUE  820  again performs a random access to the (donor) nUE  810  and re-establishes communication with it. When the wUE  820  has uplink traffic, the wUE  820  performs random access to obtain resources from the (donor) nUE  810  and moves from idle mode to connected mode. 
     Paging and Discovery Procedure 
       FIG. 9  shows an example resource allocation  900  for paging and discovery regions. According to one embodiment, the paging and discovery channel uses a central subchannel that has a bandwidth of six PRBs (6×12 subcarriers) and a subframe duration equal to that of a temporally adjacent pair of PRBs (2×7 symbols). In that subchannel and, for example, in the first subframe of each radio frame, the paging and discovery channel includes a paging region  910  and a discovery region  920  encompassing the subchannel bandwidth and nine of the symbols. The paging region  910  includes seven symbols and the discovery region  920  includes two symbols. Paging and discovery ID messages are provided in blocks of size 1×12 REs, assigned for each of the paging and discovery ID messages. 
     The paging ID message carries the paging ID. According to one embodiment, the paging ID is a short ID of the targeted wUE. The targeted wUE, if in its idle state, receives the paging ID message and wakes up to receive and transmit information in subsequent subframes. 
     The discovery ID message carries a discovery ID. According to one embodiment, a pool of discovery IDs is predefined for an entire system, and the nUE picks one discovery ID from the discovery ID pool. In another embodiment, the nUE may simply use its own short ID. The discovery IDs are broadcast IDs that are addressable to all wUEs. 
       FIG. 10  shows a pair of subframes  1000  that an nUE uses to transmit discovery ID and content messages. In other words, a first subframe is used for transmitting the discovery ID message and a subsequent subframe is used to transmit the discovery content message. For example, when a wUE detects in the paging and discovery channel of a first subframe  1010  a discovery ID corresponding to, for example, the MAC address of an accessible nUE, the wUE can use the detected discovery ID to decode the discovery content message transmitted in a second subframe  1020 . The wUE identifies a subchannel and a PRA carrying the discovery content message based on a defined map translating the discovery ID to the corresponding resources carrying the discovery content message. To reduce wUE power consumption, a mapping between MAC addresses and the discovery ID pool may be predefined for the system or by an nUE. 
       FIG. 11  shows an example subframe structure  1100  carrying a discovery content message. An SA channel includes the discovery ID used to indicate that the nUE is acquiring subsequent resources in the subframe by which to deliver discovery content. When a wUE detects the discovery ID in an SA channel (e.g., based on the aforementioned mapping of the discovery ID to the SA channel), the wUE reads the discovery content transmitted in a DL data channel  1120 . The discovery content includes the nUE&#39;s MAC address, the nUE&#39;s short ID, and a security key. An RA channel  1130  allows the wUE to then acquire resources. 
       FIG. 12  shows a discovery procedure  1200 . Initially, an nUE  1210  transmits a discovery ID in the discovery channel (e.g., region  920 ,  FIG. 9 ). The nUE  1210  then transmits an SA in the SA channel (e.g.,  1110 ,  FIG. 11 ) addressed to the discovery ID. The nUE  1210  transmits discovery content (MAC ID+nUE short ID+security key) in the following DL data channel (e.g.,  1120 ,  FIG. 11 ). 
     A wUE  1220  responds with an RA in the RA channel (e.g.,  1130 ,  FIG. 11 ) once it has detected the desired nUE from the discovery content. The RA message carries an RA-ID derived from the nUE short ID. 
     Once the nUE  1210  detects the wUE RA-ID, the nUE  1210  schedules the wUE  1220  by transmitting an SA addressed to the RA-ID in the subsequent subframes following the subframe that the RA is transmitted, i.e., the nUE responds to wUE&#39;s RA in the next subframe or a later subframe. According to one embodiment the subsequent subframe may include a second DL/UL subframe. 
     Once the wUE  1220  detects the SA from the nUE  1210 , the wUE  1220  transmits its discovery content in the data channel of the scheduled PRA. The discovery content contains: wUE MAC address, wUE short ID, security key, and UL traffic indication. 
     The nUE  1210  provides an acknowledgement (admit or decline) to the wUE RA in the ACK channel. 
     If the wUE  1220  is not scheduled in the second subframe (due to transmission collision, RA-ID collision, or other constraint), the wUE  1220  will keep sending an RA in the RA channel during the following subframes, e.g., a second DL/UL subframe of subsequent radio frames. 
     Example Devices and Circuitry 
       FIG. 13  is a block diagram illustrating electronic device circuitry  1300  that may be eNB circuitry, UE circuitry, network node circuitry, or some other type of circuitry in accordance with various embodiments. As used herein, the term “circuitry” may refer to, be part of, or include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware. 
     In embodiments, the electronic device circuitry  1300  may be, or may be incorporated into or otherwise a part of, an eNB, a UE, a network node, or some other type of electronic device. In embodiments, the electronic device circuitry  1300  may include radio transmit circuitry  1310  and receive circuitry  1312  coupled to control circuitry  1314 . In embodiments, the transmit circuitry  1310  and/or receive circuitry  1312  may be elements or modules of transceiver circuitry, as shown. The electronic device circuitry  1300  may be coupled with one or more antenna elements  1316  of one or more antennas. The electronic device circuitry  1300  and/or the components of the electronic device circuitry  1300  may be configured to perform operations similar to those described elsewhere in this disclosure. 
       FIG. 14  is a block diagram illustrating, for one embodiment, example components of a UE device  1400 . In some embodiments, the UE device  1400  may include application circuitry  1402 , baseband circuitry  1404 , radio frequency (RF) circuitry  1406 , front-end module (FEM) circuitry  1408 , and one or more antennas  1410 , coupled together at least as shown in  FIG. 14 . 
     The application circuitry  1402  may include one or more application processors. By way of non-limiting example, the application circuitry  1402  may include one or more single-core or multi-core processors. The processor(s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processor(s) may be operably coupled to and/or include memory/storage, and may be configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems to run on the system. 
     By way of non-limiting example, the baseband circuitry  1404  may include one or more single-core or multi-core processors. The baseband circuitry  1404  may include one or more baseband processors and/or control logic. The baseband circuitry  1404  may be configured to process baseband signals received from a receive signal path of the RF circuitry  1406 . The baseband circuitry  1404  may also be configured to generate baseband signals for a transmit signal path of the RF circuitry  1406 . The baseband circuitry  1404  may interface with the application circuitry  1402  for generation and processing of the baseband signals, and for controlling operations of the RF circuitry  1406 . 
     By way of non-limiting example, the baseband circuitry  1404  may include at least one of a fifth generation (5G) baseband processor  1404 A, a fourth generation (4G) baseband processor  1404 B, a third generation (3G) baseband processor  1404 C, and other baseband processor(s)  1404 D for other existing generations and generations in development or to be developed in the future (e.g., sixth generation (6G), etc.). The baseband circuitry  1404  (e.g., at least one of the baseband processors  1404 A- 1404 D) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry  1406 . By way of non-limiting example, the radio control functions may include signal modulation/demodulation, encoding/decoding, radio frequency shifting, other functions, and combinations thereof. In some embodiments, modulation/demodulation circuitry of the baseband circuitry  1404  may be programmed to perform fast Fourier transform (FFT), precoding, constellation mapping/demapping functions, other functions, and combinations thereof. In some embodiments, encoding/decoding circuitry of the baseband circuitry  1404  may be programmed to perform convolutions, tail-biting convolutions, turbo, Viterbi, Low Density Parity Check (LDPC) encoder/decoder functions, other functions, and combinations thereof. Embodiments of modulation/demodulation and encoder/decoder functions are not limited to these examples, and may include other suitable functions. 
     In some embodiments, the baseband circuitry  1404  may include elements of a protocol stack. By way of non-limiting example, elements of an evolved universal terrestrial radio access network (EUTRAN) protocol include, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU)  1404 E of the baseband circuitry  1404  may be programmed to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP, and/or RRC layers. In some embodiments, the baseband circuitry  1404  may include one or more audio digital signal processor(s) (DSP)  1404 F. The audio DSP(s)  1404 F may include elements for compression/decompression and echo cancellation. The audio DSP(s)  1404 F may also include other suitable processing elements. 
     The baseband circuitry  1404  may further include memory/storage  1404 G. The memory/storage  1404 G may include data and/or instructions for operations performed by the processors of the baseband circuitry  1404  stored thereon. In some embodiments, the memory/storage  1404 G may include any combination of suitable volatile memory and/or non-volatile memory. The memory/storage  1404 G may also include any combination of various levels of memory/storage including, but not limited to, read-only memory (ROM) having embedded software instructions (e.g., firmware), random access memory (e.g., dynamic random access memory (DRAM)), cache, buffers, etc. In some embodiments, the memory/storage  1404 G may be shared among the various processors or dedicated to particular processors. 
     Components of the baseband circuitry  1404  may be suitably combined in a single chip or a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry  1404  and the application circuitry  1402  may be implemented together, such as, for example, on a system on a chip (SOC). 
     In some embodiments, the baseband circuitry  1404  may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry  1404  may support communication with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), or a wireless personal area network (WPAN). Embodiments in which the baseband circuitry  1404  is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry. 
     The RF circuitry  1406  may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry  1406  may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. The RF circuitry  1406  may include a receive signal path, which may include circuitry to down-convert RF signals received from the FEM circuitry  1408 , and provide baseband signals to the baseband circuitry  1404 . The RF circuitry  1406  may also include a transmit signal path, which may include circuitry to up-convert baseband signals provided by the baseband circuitry  1404 , and provide RF output signals to the FEM circuitry  1408  for transmission. 
     In some embodiments, the RF circuitry  1406  may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry  1406  may include mixer circuitry  1406 A, amplifier circuitry  1406 B, and filter circuitry  1406 C. The transmit signal path of the RF circuitry  1406  may include the filter circuitry  1406 C and the mixer circuitry  1406 A. The RF circuitry  1406  may further include synthesizer circuitry  1406 D configured to synthesize a frequency for use by the mixer circuitry  1406 A of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry  1406 A of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry  1408  based on the synthesized frequency provided by the synthesizer circuitry  1406 D. The amplifier circuitry  1406 B may be configured to amplify the down-converted signals. 
     The filter circuitry  1406 C may include a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry  1404  for further processing. In some embodiments, the output baseband signals may include zero-frequency baseband signals, although this is optional, of course. In some embodiments, the mixer circuitry  1406 A of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the mixer circuitry  1406 A of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry  1406 D to generate RF output signals for the FEM circuitry  1408 . The baseband signals may be provided by the baseband circuitry  1404  and may be filtered by the filter circuitry  1406 C. The filter circuitry  1406 C may include an LPF, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the mixer circuitry  1406 A of the receive signal path and the mixer circuitry  1406 A of the transmit signal path may include two or more mixers, and may be arranged for quadrature downconversion and/or upconversion, respectively. In some embodiments, the mixer circuitry  1406 A of the receive signal path and the mixer circuitry  1406 A of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry  1406 A of the receive signal path and the mixer circuitry  1406 A of the transmit signal path may be arranged for direct downconversion and/or direct upconversion, respectively. In some embodiments, the mixer circuitry  1406 A of the receive signal path and the mixer circuitry  1406 A of the transmit signal path may be configured for super-heterodyne operation. 
     In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In other embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In such embodiments, the RF circuitry  1406  may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry, and the baseband circuitry  1404  may include a digital baseband interface to communicate with the RF circuitry  1406 . 
     In some dual-mode embodiments, separate radio integrated circuit (IC) circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, the synthesizer circuitry  1406 D may include one or more of a fractional-N synthesizer and a fractional N/N+1 synthesizer, although the scope of the embodiments is not limited in this respect, as other types of frequency synthesizers may be suitable. For example, the synthesizer circuitry  1406 D may include a delta-sigma synthesizer, a frequency multiplier, a synthesizer comprising a phase-locked loop with a frequency divider, other synthesizers, and combinations thereof. 
     The synthesizer circuitry  1406 D may be configured to synthesize an output frequency for use by the mixer circuitry  1406 A of the RF circuitry  1406  based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry  1406 D may be a fractional N/N+1 synthesizer. 
     In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO). Divider control input may be provided by either the baseband circuitry  1404  or the application circuitry  1402  depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the application circuitry  1402 . 
     The synthesizer circuitry  1406 D of the RF circuitry  1406  may include a divider, a delay-locked loop (DLL), a multiplexer, and a phase accumulator. In some embodiments, the divider may include a dual modulus divider (DMD), and the phase accumulator may include a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+1 (e.g., based on a carry-out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements; a phase detector; a charge pump; and a D-type flip-flop. In such embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL may provide negative feedback to help ensure that the total delay through the delay line is one VCO cycle. 
     In some embodiments, the synthesizer circuitry  1406 D may be configured to generate a carrier frequency as the output frequency. In some embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency, etc.) and used in conjunction with a quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some embodiments, the RF circuitry  1406  may include an IQ/polar converter. 
     The FEM circuitry  1408  may include a receive signal path, which may include circuitry configured to operate on RF signals received from one or more antennas  1410 , amplify the received signals, and provide the amplified versions of the received signals to the RF circuitry  1406  for further processing. The FEM circuitry  1408  may also include a transmit signal path, which may include circuitry configured to amplify signals for transmission provided by the RF circuitry  1406  for transmission by at least one of the antennas  1410 . 
     In some embodiments, the FEM circuitry  1408  may include a TX/RX switch configured to switch between a transmit mode and a receive mode operation. The FEM circuitry  1408  may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry  1408  may include a low-noise amplifier (LNA) to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry  1406 ). The transmit signal path of the FEM circuitry  1408  may include a power amplifier (PA) configured to amplify input RF signals (e.g., provided by RF circuitry  1406 ), and one or more filters configured to generate RF signals for subsequent transmission (e.g., by one or more of the antennas  1410 ). 
     In some embodiments, the UE device  1400  may include additional elements such as, for example, memory/storage, a display, a camera, one or more sensors, an input/output (I/O) interface, other elements, and combinations thereof. 
     In some embodiments, the UE device  1400  may be configured to perform one or more processes, techniques, and/or methods as described herein, or portions thereof. 
     In embodiments where the UE device  1400  or its electronic circuitry (e.g., circuitry  1300 ) is, implements, is incorporated into, or is otherwise part of an nUE, baseband circuitry  1404  may be to indicate a paging and resource allocation to a wUE (wearable UE) to enable a transition of the wUE from a first communication operation state to a second low power operation state that includes powering up radio frequency (RF) circuitry of the wUE according to an interval associated with the paging and resource allocation, and operate in a communication operation state to receive a communication on behalf of the wUE. The RF circuitry  1406  may be to transmit a signal based on the communication at a time corresponding to a next occurrence of the paging interval. 
     In embodiments where the UE device  1400  is, implements, is incorporated into, or is otherwise part of a wUE, baseband circuitry  1404  may be to baseband circuitry coupled to the RF circuitry, the baseband circuitry to: identify a paging and resource allocation to a wUE (wearable UE) to enable a transition of the wUE from a first communication operation state to a second low power operation state that includes powering up radio frequency (RF) circuitry of the wUE according to an interval associated with the paging and resource allocation, and operate in a communication operation state to receive a communication on behalf of the wUE. The RF circuitry  1406  may be to transmit a signal based on the communication at a time corresponding to a next occurrence of the paging interval. 
     In some embodiments, the UE device  1400  of  FIG. 14  may be configured to perform one or more processes, techniques, and/or methods as described herein, or portions thereof. Embodiments described herein may be implemented into a system using any suitably configured hardware and/or software. In the software context, various techniques, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, a non-transitory computer readable storage medium, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the various techniques. In the case of program code execution on programmable computers, the computing device may include a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. The volatile and non-volatile memory and/or storage elements may be a RAM, an EPROM, a flash drive, an optical drive, a magnetic hard drive, or another medium for storing electronic data. The eNB (or other base station) and UE (or other mobile station) may also include a transceiver component, a counter component, a processing component, and/or a clock component or timer component. One or more programs that may implement or utilize the various techniques described herein may use an application programming interface (API), reusable controls, and the like. Such programs may be implemented in a high-level procedural or an object-oriented programming language to communicate with a computer system. However, the program(s) may be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or an interpreted language, and combined with hardware implementations. 
     It should be understood that many of the functional units described in this specification may be implemented as one or more components, which is a term used to more particularly emphasize their implementation independence. For example, a component may be implemented as a hardware circuit comprising custom very large scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A component may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, or the like. 
     Components may also be implemented in software for execution by various types of processors. An identified component of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, a procedure, or a function. Nevertheless, the executables of an identified component need not be physically located together, but may comprise disparate instructions stored in different locations that, when joined logically together, comprise the component and achieve the stated purpose for the component. 
     Indeed, a component of executable code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within components, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. The components may be passive or active, including agents operable to perform desired functions. 
       FIG. 15  is a block diagram illustrating components, according to some example embodiments, able to read instructions from a machine-readable or computer-readable medium (e.g., a machine-readable storage medium) and perform any one or more of the methodologies discussed herein. Specifically,  FIG. 15  shows a diagrammatic representation of hardware resources  1500  including one or more processors (or processor cores)  1510 , one or more memory/storage devices  1520 , and one or more communication resources  1530 , each of which are communicatively coupled via a bus  1540 . 
     The processors  1510  (e.g., a central processing unit (CPU), a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU), a digital signal processor (DSP) such as a baseband processor, an application specific integrated circuit (ASIC), a radio-frequency integrated circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, a processor  1512  and a processor  1514 . The memory/storage devices  1520  may include main memory, disk storage, or any suitable combination thereof. 
     The communication resources  1530  may include interconnection and/or network interface components or other suitable devices to communicate with one or more peripheral devices  1504  and/or one or more databases  1506  via a network  1508 . For example, the communication resources  1530  may include wired communication components (e.g., for coupling via a Universal Serial Bus (USB)), cellular communication components, Near Field Communication (NFC) components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components. 
     Instructions  1550  may comprise software, a program, an application, an applet, an app, or other executable code for causing at least one of the processors  1510  to perform any one or more of the methodologies discussed herein. The instructions  1550  may reside, completely or partially, within at least one of the processors  1510  (e.g., within the processor&#39;s cache memory), the memory/storage devices  1520 , or any suitable combination thereof. Furthermore, any portion of the instructions  1550  may be transferred to the hardware resources  1500  from any combination of the peripheral devices  1504  and/or the databases  1506 . Accordingly, the memory of the processors  1510 , the memory/storage devices  1520 , the peripheral devices  1504 , and the databases  1506  are examples of computer-readable and machine-readable media. 
     EXAMPLES 
     Reference throughout this specification to “an example” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment. Thus, appearances of the phrase “in an example” in various places throughout this specification are not necessarily all referring to the same embodiment. 
     Example 1 
     An apparatus of a wearable user equipment (wUE), the apparatus comprising circuitry to: process a discovery channel to obtain, from a network user equipment (nUE) during a first subframe, a discovery identifier (ID) message including a discovery ID associated with the nUE; detect the discovery ID in a scheduling assignment (SA) channel during one or more second subframes following the first subframe, the discovery ID indicating the nUE is scheduling resources for exchanging discovery content messages by which to transition the wUE from a power-saving mode (PSM) to a discovery state; and process a downlink (DL) data channel to obtain the discovery content messages and thereby cause the wUE to transition from the discovery state to a communication state for exchange of data with the nUE through an Xu-a air interface in a personal area network (PAN) with the nUE. The apparatus also optionally comprises transceiver circuitry. 
     Example 2 
     The apparatus of example 1, in which the circuitry is further configured to detect a period of inactive communication with the nUE and indicate the wUE transition to an idle state. 
     Example 3 
     The apparatus of example 1 or 2, in which the circuitry is further configured to transition to the PSM after being in an idle state. 
     Example 4 
     The apparatus of any of examples 1-3, in which the circuitry is further configured to: process DL data received from the nUE through the Xu-a air interface in a data channel of a scheduled subframe following the one of more second subframes; and in response to processing the DL data, generate an acknowledgement (ACK) for an ACK channel of the scheduled subframe. 
     Example 5 
     The apparatus of any of examples 1-4, in which each subframe includes a subchannel comprising scheduling assignment, data, and random access channels spaced apart by associated guard periods. 
     Example 6 
     The apparatus of any of examples 1-5, in which the first subframe includes a subchannel comprising synchronization signal (SS), broadcast, paging, and the discovery channels. 
     Example 7 
     The apparatus of any of examples 1-6, in which the discovery channel is temporally adjacent to a paging channel so as to define a paging and discovery channel having corresponding paging and discovery regions. 
     Example 8 
     The apparatus of any of examples 1-7, in which the first and the one or more second subframes include multiple subchannels, each of the subchannels having a bandwidth equal to that of six physical resource blocks (PRB). 
     Example 9 
     The apparatus of any of examples 1-8, in which the discovery ID identifies a channel of the one or more second subframes that includes a discovery content message. 
     Example 10 
     The apparatus of example 9, in which the circuitry is further configured to determine the channel based on a mapping defining a location of the channel based on the discovery ID. 
     Example 11 
     A method performed by a wearable user equipment (wUE), the method comprising: receiving from a network user equipment (nUE) a discovery identifier (ID) message provided in a discovery channel transmitted during a first subframe; in response to the discovery ID message, transitioning from a power-saving mode (PSM) to a discovery state for exchange of discovery content messages with the nUE, the discovery content messages transmitted in one or more second subframes following the first subframe; and in response to exchange of the discovery content messages, establishing an Xu-a air interface in a personal area network (PAN) with the nUE and transition to a communication state for exchange of data with the nUE through the Xu-a air interface. 
     Example 12 
     The method of example 11, further comprising transitioning to an idle state in response to a period of inactive communication with the nUE. 
     Example 13 
     The method of example 11 or 12, further comprising transitioning to the PSM after being in an idle state. 
     Example 14 
     The method of any of examples 11-13, further comprising: receiving from the nUE, through the Xu-a air interface, downlink (DL) data in a data channel of a scheduled subframe following the one of more second subframes; and in response to the DL data, transmitting an acknowledgement (ACK) in an ACK channel of the scheduled subframe. 
     Example 15 
     The method of any of examples 11-14, in which each subframe includes a subchannel comprising scheduling assignment, data, and random access channels spaced apart by associated guard periods. 
     Example 16 
     The method of any of examples 11-15, in which the first subframe includes a subchannel comprising synchronization signal (SS), broadcast, paging, and the discovery channels spaced apart by associated guard periods. 
     Example 17 
     The method of any of examples 11-16, in which the discovery channel is temporally adjacent to a paging channel so as to define a paging and discovery channel having corresponding paging and discovery regions. 
     Example 18 
     The method of any of examples 11-17, in which the first and the one or more second subframes include multiple subchannels, each of the subchannels having a bandwidth equal to that of six physical resource blocks (PRB). 
     Example 19 
     The method of any of examples 11-18, in which the discovery ID identifies a channel of the one or more second subframes that includes a discovery content message. 
     Example 20 
     The method of example 19, further comprising determining the channel based on a mapping defining a location of the channel based on the discovery ID. 
     Example 21 
     An apparatus of a network user equipment (nUE) comprising circuitry configured to: generate a discovery message in a discovery channel during a first subframe, the discovery message including a discovery identifier (ID) for a wearable user equipment (wUE); generate a scheduling assignment in a scheduling assignment channel during a second subframe, the scheduling assignment addressed to the discovery ID of the discovery message; generate discovery message content in a data channel of the second subframe; and in response to the wUE receiving the discovery message content and transmitting a random access (RA), process the RA obtained from the wUE in an RA channel of the second subframe. The apparatus also optionally comprises transceiver circuitry. 
     Example 22 
     The apparatus of example 21, in which the circuitry is configured to generate a paging message in a paging channel during the first subframe. 
     Example 23 
     The apparatus of example 21 or 22, in which the circuitry is configured select the discovery ID from a pool of predetermined discovery IDs. 
     Example 24 
     The apparatus of any of examples 21-23, in which the circuitry is configured to provide a synchronization signal (SS) in an SS channel of the first subframe. 
     Example 25 
     The apparatus of any of examples 21-24, in which the RA includes an RA identifier (RA-ID). 
     Example 26 
     The apparatus of any of examples 21-25, in which the circuitry is further configured to process a synchronization signal from an evolved Node B (eNB) to maintain synchronization in a personal area network (PAN) formed between the nUE and the wUE. 
     Example 27 
     A method performed by a network user equipment (nUE), comprising: transmitting to a wearable user equipment (wUE) a discovery message in a discovery channel during a first subframe, the discovery message including a discovery identifier (ID); transmitting a scheduling assignment in a scheduling assignment channel during a second subframe, the scheduling assignment addressed to the discovery ID of the discovery message; transmitting discovery message content in a data channel of the second subframe; and receiving a random access (RA) in an RA channel of the second subframe. 
     Example 28 
     The method of example 27, further comprising transmitting a paging message in a paging channel during the first subframe. 
     Example 29 
     The method of example 27 or 28, further comprising selecting the discovery ID from a pool of predetermined discovery IDs. 
     Example 30 
     The method of any of examples 27-29, further comprising providing a synchronization signal (SS) in an SS channel of the first subframe. 
     Example 31 
     The method of any of examples 27-30, in which the RA includes an RA identifier (RA-ID). 
     Example 32 
     The method of any of examples 27-32, further comprising receiving from an evolved Node B (eNB) a synchronization signal to maintain synchronization in a personal area network (PAN) formed between the nUE and the wUE. 
     Example 33 
     An apparatus of a wearable user equipment (wUE) comprising circuitry configured to: generate a random access (RA) to join a personal area network (PAN) including an Xu-a intra-PAN air interface for short-range wireless communication between the wUE and a network user equipment (nUE), the nUE including a protocol stack for accessing, through a Uu-p air interface between the nUE and a base station, control- and user-plane functions of a long-term evolution (LTE) wide area network (WWAN) comprising the nUE and the base station; process a scheduling assignment from the nUE; and generate uplink data for providing to the nUE through the Xu-a intra-PAN air interface during a scheduled subframe to facilitate the wUE in its communication with the LTE WWAN. The apparatus also optionally comprises transceiver circuitry. 
     Example 34 
     The apparatus of example 33, in which the wUE is a first wUE comprising circuitry configured to generate uplink data for providing to a second wUE in the PAN through a Xu-b intra-PAN air interface between the first and second wUEs. 
     Example 35 
     The apparatus of example 33 or 34, in which the circuitry is configured to communicate with the base station through a Uu-w air interface between the wUE and the base station. 
     Example 36 
     The apparatus of any of examples 33-35, in which the wUE is configured to process a synchronization signal from the base station for synchronizing the nUE and the wUE within one cluster. 
     Example 37 
     The apparatus of any of examples 33-36, in which the circuitry is configured to process subframes in a radio frame that is aligned for collision avoidance. 
     Example 38 
     The apparatus of any of examples 33-37, in which the circuitry is configured to perform blind detection. 
     Example 39 
     The apparatus of any of examples 33-38, in which the subframe comprises multiple guard periods, a scheduling assignment (SA) channel, a data transmission channel, and an acknowledgement (ACK) channel to signal feedback corresponding to data processed in the data transmission channel during a transmission within the subframe that includes the ACK channel. 
     Example 40 
     The apparatus of example 39, in which the subframe further comprises a scheduling assignment response (SAR) channel temporally adjacent a first guard period of the multiple guard periods, the first guard period located between the SA channel and the SAR channel. 
     Example 41 
     The apparatus of example 39, in which the subframe further comprises an RA channel temporally adjacent a first guard period of the multiple guard periods, the first guard period located between the SA channel and the RA channel. 
     Example 42 
     The apparatus of any of examples 33-41, in which the circuitry is configured to process from the nUE a message to configure a ratio of uplink and downlink subframes of a time-division duplex (TDD) radio frame structure. 
     Example 43 
     A method performed by a wearable user equipment (wUE), comprising: joining a personal area network (PAN) including an Xu-a intra-PAN air interface for short-range wireless communication between the wUE and a network user equipment (nUE), the nUE including a protocol stack for accessing, through a Uu-p air interface between the nUE and a base station, control- and user-plane functions of a long-term evolution (LTE) wide area network (WWAN) comprising the nUE and the base station; and communicating with the nUE through the Xu-a intra-PAN air interface to facilitate the wUE in its communication with the LTE WWAN. 
     Example 44 
     The method of example 43, in which the wUE is a first wUE comprising circuitry configured to communicate with a second wUE in the PAN through a Xu-b intra-PAN air interface between the first and second wUEs. 
     Example 45 
     The method of example 43 or 44, further comprising communicating with the base station through a Uu-w air interface between the wUE and the base station. 
     Example 46 
     The method of any of examples 43-45, further comprising receiving from the base station a synchronization signal for synchronizing the nUE and the wUE within one cluster. 
     Example 47 
     The method of any of examples 43-46, further comprising receiving subframes in a radio frame that is aligned for collision avoidance. 
     48. The method of any of examples 43-47, further comprising performing blind detection. 
     Example 49 
     The method of any of examples 43-48, further comprising communicating with the nUE through a self-contained radio frame structure including a subframe, the subframe comprising multiple guard periods, a scheduling assignment (SA) channel, a data transmission channel, and an acknowledgement (ACK) channel to signal feedback corresponding to data received in the data transmission channel during a transmission within the subframe that includes the ACK channel. 
     Example 50 
     The method of example 49, in which the subframe further comprises a scheduling assignment response (SAR) channel temporally adjacent a first guard period of the multiple guard periods, the first guard period located between the SA channel and the SAR channel. 
     Example 51 
     The method of example 59, in which the subframe further comprises a random access (RA) channel temporally adjacent a first guard period of the multiple guard periods, the first guard period located between the SA channel and the RA channel. 
     Example 52 
     The method of any of examples 43-51, further comprising receiving from the nUE a message to configure a ratio of uplink and downlink subframes of a time-division duplex (TDD) radio frame structure. 
     Example 53 
     A method of state transition for intra-PAN communication as defined in  FIG. 2 . 
     Example 54 
     A method of frame structure for intra-PAN communication as defined in  FIG. 3 . 
     Example 55 
     A method of numerology and subframe length considering implementation complexity and overhead. 
     Example 56 
     A method of subframe structure for intra-PAN communication as defined in  FIG. 4, 5, 6 , or  7 . 
     Example 57 
     A method of self-contained frame structure for intra-PAN communication. 
     Example 58 
     A method of collision avoidance signal exchange procedure within each subframe. 
     Example 59 
     A method L1 procedure for intra-PAN communication as defined in  FIG. 8 . 
     Example 60 
     A method of paging and discovery channel as defined in  FIG. 9 . 
     Example 61 
     A method to define discovery ID pool for discovery. 
     Example 62 
     A method of discovery message multiplexed in user traffic as illustrated in  FIG. 10 . 
     Example 63 
     A method of subframe for discovery message as defined in  FIG. 11 . 
     Example 64 
     A method of discovery procedure and random access procedure as defined in  FIG. 12 . 
     Example 65 
     An apparatus comprising means to perform one or more elements of a method described in or related to any of examples 11-20, 27-32, or 43-64, and/or any other method or process described herein. 
     Example 66 
     One or more non-transitory (or transitory) computer-readable media comprising instructions to cause an electronic device, upon execution of the instructions by one or more processors of the electronic device, to perform one or more elements of a method described in or related to any of examples 11-20, 27-32, or 43-64, and/or any other method or process described herein. 
     Example 67 
     An apparatus comprising control logic, transmit logic, and/or receive logic to perform one or more elements of a method described in or related to any of examples 11-20, 27-32, or 43-64, and/or any other method or process described herein. 
     Example 68 
     A method of communicating in a wireless network as shown and described herein. 
     Example 69 
     A system for providing wireless communication as shown and described herein. 
     Example 70 
     A device for providing wireless communication as shown and described herein. 
     Skilled persons will understand that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. For example, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. Lists, however, should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on its presentation in a common group without indications to the contrary. In addition, various embodiments and examples may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of embodiments. The scope of the present invention should, therefore, be determined only by the following claims.