# US 2016/0262084 A1 · User terminal and inter-terminal communication method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0262084 A1 - Document ID: US20160262084A1 - Status: Published application - Kind: A1 - Application number: 15/032,720 - Filed: 2014-10-16 - Published: 2016-09-08 - Earliest claimed: 2013-10-31 - Assignees: Ntt Docomo, Inc. - Applicants: Ntt Docomo, Inc. - Inventors: Hiroki Harada; Yongbo Zeng; Qun Zhao; Yongsheng Zhang - Web page: https://patentgrep.com/patent/US20160262084A1 ## CPC - H04W 40/244: {using a network of reference devices, e.g. beaconing} - H04J 11/00: Orthogonal multiplex systems, {e.g. using WALSH codes}(H04J13/00 takes precedence) - H04J 11/0056: {Inter-base station aspects} - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L 5/005: {of common pilots, i.e. pilots destined for multiple users or terminals} - H04L 27/10: Frequency-modulated carrier systems, i.e. using frequency-shift keying (H04L27/32 takes precedence) - H04L 69/22: Parsing or analysis of headers - H04W 8/005: {Discovery of network devices, e.g. terminals} - H04W 72/1215: {for collaboration of different radio technologies} - H04W 72/1263: Mapping of traffic onto schedule, e.g. scheduled allocation or multiplexing of flows - H04L 27/34: Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems - H04W 40/246: {Connectivity information discovery} - H04W 88/06: adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract The present invention is designed so that, when a plurality of inter-terminal discovery signals with varying numbers of information bits are used in a radio communication system in which inter-terminal communication is carried out, user terminals can be discovered based on the inter-terminal discovery signals. According to the inter-terminal communication method of the present invention, a user terminal (#1) determines the signal format of a discovery signal based on the number of information bits of the discovery signal, transmits the discovery signal based on the signal format, and also transmits signal format information to represent this signal format. A user terminal (#2) receives the signal format information from the user terminal (#1), and, based on the signal format represented by the signal format information, detects the discovery signal. ## Claims ### Claim 1 A user terminal that transmits an inter-terminal discovery signal to another user terminal without involving a radio base station, the user terminal comprising: a determining section that determines a signal format of the inter-terminal discovery signal based on the number of information bits of the inter-terminal discovery signal; and a transmission section that transmits the inter-terminal discovery signal based on the signal format, and also transmits signal format information that represents the signal format. ### Claim 2 (depends on 1) The user terminal according to claim 1, wherein: a plurality of signal sequences included in a sequence set are classified into a plurality of sequence subsets that are each associated with a different signal format; and the signal format information is a signal sequence that is selected from a sequence subset associated with the signal format determined in the determining section. ### Claim 3 (depends on 2) The user terminal according to claim 2, wherein the transmission section multiplexes and transmits the inter-terminal discovery signal and the selected signal sequence in time division multiplexing and/or frequency division multiplexing. ### Claim 4 (depends on 1) The user terminal according to claim 1, wherein: the inter-terminal discovery signal is formed by including a control head and a payload; and the signal format information is included in the control head. ### Claim 5 (depends on 4) The user terminal according to claim 4, wherein the control head is mapped to a same number of resource units in a frequency direction as those of the payload, mapped to a predetermined number of resource units in the frequency direction regardless of a number of resource units of the payload in the frequency direction, or duplicated and mapped based on the number of resource units of the payload in the frequency direction. ### Claim 6 (depends on 1) The user terminal according to claim 1, wherein the signal format is at least one of a modulation scheme of the inter-terminal discovery signal, a coding rate of the inter-terminal discovery signal and a number of resource units where the inter-terminal discovery signal is mapped. ### Claim 7 (depends on 1) The user terminal according to claim 1, wherein the transmission section transmits the inter-terminal discovery signal in transmission durations of a predetermined cycle. ### Claim 8 (depends on 7) The user terminal according to claim 7, wherein: the transmission duration includes a plurality of durations that vary for every number of resource units where the inter-terminal discovery signal is mapped; and the transmission section transmit the inter-terminal discovery signal in durations for the number of resource units where the inter-terminal discovery signal is mapped. ### Claim 9 A user terminal that receives an inter-terminal discovery signal from another user terminal without involving a radio base station, the user terminal comprising: a receiving section that receives signal format information of the inter-terminal discovery signal from the other user terminal; and a detection section that detects the inter-terminal discovery signal based on a signal format represented by the signal format information. ### Claim 10 An inter-terminal communication method for use in a radio communication system in which an inter-terminal discovery signal is transmitted from a first user terminal to a second user terminal without involving a radio base station, the inter-terminal communication method comprising the steps of: in the first user terminal: determining a signal format of the inter-terminal discovery signal based on a number of information bits of the inter-terminal discovery signal; and transmitting the inter-terminal discovery signal based on the signal format, and also transmitting signal format information that represents the signal format; and in the second user terminal: receiving the signal format information from the first user terminal; and detecting the inter-terminal discovery signal based on the signal format represented by the signal format information.