WO2019061259A1

WO2019061259A1 - Encoding and decoding for messages with partial common content

Info

Publication number: WO2019061259A1
Application number: PCT/CN2017/104277
Authority: WO
Inventors: Kai Chen; Thomas Richardson; Changlong Xu; Chao Wei
Original assignee: Qualcomm Incorporated
Priority date: 2017-09-29
Filing date: 2017-09-29
Publication date: 2019-04-04

Abstract

Methods, systems, and devices for wireless communications are described. Generally, the described techniques provide for encoding and decoding of transmission with partial common content. The described techniques leverage the mathematical properties of a linear encoding operation to reduce encoding and decoding complexity without a significant deterioration in coding gain and system throughput. In aspects, a device that receives multiple codewords that contain a common portion may jointly process the codewords to decode the variable portion, the common portion, or both. The described techniques may in some cases be supported through the use of differential encoding, which may support the efficient joint processing of the codewords. In some cases, the encoding and decoding techniques may be based on a nested coding design, which may improve the coding gain of the system.

Description

ENCODING AND DECODING FOR MESSAGES WITH PARTIAL COMMON CONTENT

BACKGROUND

The following relates generally to wireless communication， and more specifically to encoding and decoding for messages with partial common content.

Wireless communications systems are widely deployed to provide various types of communication content such as voice， video， packet data， messaging， broadcast， and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g.， time， frequency， and power) . Examples of such multiple-access systems include fourth generation (4G) systems such as a Long Term Evolution (LTE) systems or LTE-Advanced (LTE-A) systems， and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA) ， time division multiple access (TDMA) ， frequency division multiple access (FDMA) ， orthogonal frequency division multiple access (OFDMA) ， or discrete Fourier transform-spread-OFDM (DFT-s-OFDM) . A wireless multiple-access communications system may include a number of base stations or network access nodes， each simultaneously supporting communication for multiple communication devices， which may be otherwise known as user equipment (UE) .

Some wireless communications systems may support periodic (e.g.， or aperiodic) transmission of messages with partial common content. For example， such systems may employ beamforming techniques that support beamsweeping of transmissions across a coverage area. Additionally or alternatively， such systems may support omni-directional repeated transmissions with partial common content. In each case， at least a portion of the payload of the transmissions may not vary in time (e.g.， or may vary slowly such that it is considered fixed for at least a specific time interval) . An example of such a relatively static portion is a payload of a system information transmission (e.g.， which may indicate a system bandwidth or other such information) . A device receiving multiple such transmissions may benefit from combining the transmissions (e.g.， which may effectively boost the signal power of the transmissions and improve a likelihood of successfully decoding the payload) . However， because a second portion of these transmissions may vary in time， complications may arise when performing the combining operation. Improved techniques for encoding and decoding messages with partial common content may be desired.

SUMMARY

The described techniques relate to improved methods， systems， devices， or apparatuses that support encoding and decoding for messages with partial common content. In difficult communication environments (e.g.， in which a signal to noise ratio (SNR) is not optimal) ， multiple received codewords may be soft-combined before decoding in order to improve the power or coding gain. Generally， the described techniques provide for differential decoding before performing a soft combining operation and encoding considerations in support of the same. In some wireless communications systems， part of a transmission may be fixed (e.g.， the same for multiple instances of the transmission) while another part of the transmission may be changed (e.g.， periodically) . An example is provided in the context of a physical broadcast channel (PBCH) ， which carries radio frame timing and other configuration information (e.g.， system bandwidth， etc. ) . For PBCH， the system configuration information portion may represent a fixed portion (e.g.， which may be static or semi-statically updated) while the timing information may periodically increment (e.g.， from 0 to 1023) before resetting.

Because of the varying nature of the timing information， its effect on a received codeword may interfere with a soft-combining operation involving the received codeword and a subsequently received codeword (e.g.， which has different timing information) . For example， multiple trials may be required when decoding the received codeword (e.g.， where each trial is associated with a given timing bit hypothesis) ； however， multiple such decoding trials may be correlated with a higher undetected error rate (e.g.， where an “undetected error” refers to a decoding event in which the decoder erroneously classifies a decoded codeword as valid) . Techniques described herein support a reduction in the number of decoding trials， which may contribute to suppressing the undetected error rate and in turn improve throughput for the communications system. Additionally or alternatively， scenarios may exist in which a receiving device is only interested in the variable portion (e.g.， the timing information) . Techniques described herein support a reduction in the number of bits to be decoded to glean this information， which may reduce decoding complexity and lower power consumption.

A method of wireless communication is described. The method may include applying an encoding operation to a first input vector to generate a first component codeword to be used for a plurality of codewords transmitted in a plurality of corresponding time intervals， applying the encoding operation to a plurality of second input vectors to generate a respective plurality of second component codewords， combining， for each of the plurality of codewords， the first component codeword with a respective second component codeword， and transmitting the plurality of codewords in the plurality of corresponding time intervals.

An apparatus for wireless communication is described. The apparatus may include means for applying an encoding operation to a first input vector to generate a first component codeword to be used for a plurality of codewords transmitted in a plurality of corresponding time intervals， means for applying the encoding operation to a plurality of second input vectors to generate a respective plurality of second component codewords， means for combining， for each of the plurality of codewords， the first component codeword with a respective second component codeword， and means for transmitting the plurality of codewords in the plurality of corresponding time intervals.

Another apparatus for wireless communication is described. The apparatus may include a processor， memory in electronic communication with the processor， and instructions stored in the memory. The instructions may be operable to cause the processor to apply an encoding operation to a first input vector to generate a first component codeword to be used for a plurality of codewords transmitted in a plurality of corresponding time intervals， apply the encoding operation to a plurality of second input vectors to generate a respective plurality of second component codewords， combine， for each of the plurality of codewords， the first component codeword with a respective second component codeword， and transmit the plurality of codewords in the plurality of corresponding time intervals.

A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to apply an encoding operation to a first input vector to generate a first component codeword to be used for a plurality of codewords transmitted in a plurality of corresponding time intervals， apply the encoding operation to a plurality of second input vectors to generate a respective plurality of second component codewords， combine， for each of the plurality of codewords， the first component codeword with a respective second component codeword， and transmit the plurality of codewords in the plurality of corresponding time intervals.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， each second input vector comprises a respective coded sequence， a difference between any coded sequences that correspond to adjacent time intervals being distinct from any other difference between coded sequences corresponding to adjacent time intervals.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the first input vector may be associated with a first set of bit positions of the encoding operation having a first decoding error rate and each second input vector may be associated with a second set of bit positions of the encoding operation having a second decoding error rate lower than the first decoding error rate.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of highest reliability bit channels.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar code.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， each of the plurality of second input vectors comprises a bit stream corresponding to a respective system frame number (SFN) .

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， each of the plurality of second input vectors comprises a respective plurality of error detecting check bits covering the respective SFN and a payload of the first input vector.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， each of the plurality of codewords comprises a PBCH.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the encoding operation comprises a linear encoding operation.

A method of wireless communication is described. The method may include receiving a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits， receiving a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits， identifying a difference between the first codeword and the second codeword， and decoding the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits.

An apparatus for wireless communication is described. The apparatus may include means for receiving a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits， means for receiving a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits， means for identifying a difference between the first codeword and the second codeword， and means for decoding the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits.

Another apparatus for wireless communication is described. The apparatus may include a processor， memory in electronic communication with the processor， and instructions stored in the memory. The instructions may be operable to cause the processor to receive a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits， receive a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits， identify a difference between the first codeword and the second codeword， and decode the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits.

A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to receive a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits， receive a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits， identify a difference between the first codeword and the second codeword， and decode the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， identifying the difference comprises： performing a log-likelihood ratio (LLR) exclusive-or (XOR) operation between codeword values for each bit position of the first and second codewords.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the set of fixed bits may be associated with a first set of bit positions of a decoding operation having a first decoding error rate and a respective set of variable bits may be associated with a second set of bit positions of the decoding operation having a second decoding error rate lower than the first decoding error rate.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the decoding operation may be a polar decoding operation， and the second set of bit positions corresponds to a set of highest reliability bit channels.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the decoding operation may be a polar decoding operation， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar decoding operation.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the first set of variable bits comprises a first variable payload and a first plurality of error detecting check bits covering the first variable payload and the set of fixed bits.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the first variable payload comprises a SFN.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， each of the first and second codewords comprises a PBCH.

A method of wireless communication is described. The method may include receiving a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits， receiving a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits， applying a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword， combining the second codeword and the hypothesized second codeword to obtain a combined codeword， and performing a decoding operation on the combined codeword to obtain a representation of the second input vector.

An apparatus for wireless communication is described. The apparatus may include means for receiving a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits， means for receiving a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits， means for applying a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword， means for combining the second codeword and the hypothesized second codeword to obtain a combined codeword， and means for performing a decoding operation on the combined codeword to obtain a representation of the second input vector.

Another apparatus for wireless communication is described. The apparatus may include a processor， memory in electronic communication with the processor， and instructions stored in the memory. The instructions may be operable to cause the processor to receive a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits， receive a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits， apply a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword， combine the second codeword and the hypothesized second codeword to obtain a combined codeword， and perform a decoding operation on the combined codeword to obtain a representation of the second input vector.

A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to receive a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits， receive a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits， apply a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword， combine the second codeword and the hypothesized second codeword to obtain a combined codeword， and perform a decoding operation on the combined codeword to obtain a representation of the second input vector.

Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for receiving a third codeword generated from a third input vector comprising a third set of variable bits and the set of fixed bits. Some examples of the method， apparatus， and non- transitory computer-readable medium described above may further include processes， features， means， or instructions for applying a difference between the third codeword and the second codeword to the third codeword to obtain a second hypothesized second codeword. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for combining the second codeword， the hypothesized second codeword， and the second hypothesized second codeword to obtain a second combined codeword. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for performing the decoding operation on the second combined codeword to obtain a second representation of the second input vector.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， applying the difference between the first codeword and the second codeword comprises： decoding a difference vector to generate a decoding candidate. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for re-encoding the decoding candidate to produce a candidate variable component codeword. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for performing a LLR XOR operation between codeword values for each bit position of the first codeword and the candidate variable component codeword.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a system for wireless communication that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a wireless device that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure.

FIG. 3 illustrates an example of a process flow that supports encoding for messages with partial common content in accordance with aspects of the present disclosure.

FIG. 4 illustrates an example of a process flow that supports decoding for messages with partial common content in accordance with aspects of the present disclosure.

FIGs. 5A and 5B illustrate example encoding configurations that support encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure.

FIG. 6 illustrates an example of a process flow that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure.

FIGs. 7 through 9 show block diagrams of a device that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure.

FIG. 10 illustrates a block diagram of a system including a base station that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure.

FIGs. 11 through 13 show block diagrams of a device that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure.

FIG. 14 illustrates a block diagram of a system including a UE that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure.

FIGs. 15 through 17 illustrate methods for encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

Techniques are described that support encoding and decoding for messages with partial common content. For example， the described techniques may relate to transmission of system information， portions of which vary slowly in time or remain static. For example， a given cell of a communications system may support a given system bandwidth for at least a specific time interval. This bandwidth may be indicated to devices associated with the cell in the form of a PBCH transmission， which may additionally contain time-varying information (e.g.， such as a timing index of the transmission) . Because of the juxtaposition of the fixed information and the varying information， complications may arise when attempting to combine multiple received codewords (e.g.， because each received codeword may share a common portion but be associated with a respective variable portion) . It is to be understood that the term “fixed” as used herein to refer to information encoded in a codeword may not necessarily convey immutability； rather， any portion of a payload that is common to two or more sequential transmissions may be referred to as “fixed” for a given time interval corresponding to the two or more sequential transmissions. Similarly， while the present disclosure is described in the context of PBCH transmissions， it is to be understood that the described techniques may be extended to any communication scenario which employs messages with partial common (e.g.， fixed) content.

Aspects of the disclosure are initially described in the context of a wireless communications system. Aspects of the disclosure are then illustrated by and described in the context of block diagrams and process flows that support encoding and decoding for messages with partial common content. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams， system diagrams， and flowcharts that relate to encoding and decoding for messages with partial common content.

FIG. 1 illustrates an example of a wireless communications system 100 in accordance with various aspects of the present disclosure. The wireless communications system 100 includes base stations 105， UEs 115， and a core network 130. In some examples， the wireless communications system 100 may be an LTE network， an LTE-Anetwork， or a NR network. In some cases， wireless communications system 100 may support enhanced broadband communications， ultra-reliable (e.g.， mission critical) communications， low latency communications， or communications with low-cost and low-complexity devices. The base stations 105 and UEs 115 may support techniques described herein. For example， a base

Base stations 105 may wirelessly communicate with UEs 115 via one or more base station antennas. Base stations 105 described herein may include or may be referred to by those skilled in the art as a base transceiver station， a radio base station， an access point， a radio transceiver， a NodeB， an eNodeB (eNB) ， a next-generation Node B or giga-nodeB (either of which may be referred to as a gNB) ， a Home NodeB， a Home eNodeB， or some other suitable terminology. Wireless communications system 100 may include base stations 105 of different types (e.g.， macro or small cell base stations) . The UEs 115 described herein may be able to communicate with various types of base stations 105 and network equipment including macro eNBs， small cell eNBs， gNBs， relay base stations， and the like.

Each base station 105 may be associated with a particular geographic coverage area 110 in which communications with various UEs 115 is supported. Each base station 105 may provide communication coverage for a respective geographic coverage area 110 via communication links 125， and communication links 125 between a base station 105 and a UE 115 may utilize one or more carriers. Communication links 125 shown in wireless communications system 100 may include uplink transmissions from a UE 115 to a base station 105， or downlink transmissions， from a base station 105 to a UE 115. Downlink transmissions may also be called forward link transmissions while uplink transmissions may also be called reverse link transmissions.

The geographic coverage area 110 for a base station 105 may be divided into sectors making up only a portion of the geographic coverage area 110， and each sector may be associated with a cell. For example， each base station 105 may provide communication coverage for a macro cell， a small cell， a hot spot， or other types of cells， or various combinations thereof. In some examples， a base station 105 may be movable and therefore provide communication coverage for a moving geographic coverage area 110. In some examples， different geographic coverage areas 110 associated with different technologies may overlap， and overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station 105 or by different base stations 105. The wireless communications system 100 may include， for example， a heterogeneous LTE/LTE-Aor NR network in which different types of base stations 105 provide coverage for various geographic coverage areas 110.

The term “cell” refers to a logical communication entity used for communication with a base station 105 (e.g.， over a carrier) ， and may be associated with an identifier for distinguishing neighboring cells (e.g.， a physical cell identifier (PCID) ， a virtual cell identifier (VCID) ) operating via the same or a different carrier. In some examples， a carrier may support multiple cells， and different cells may be configured according to different protocol types (e.g.， machine-type communication (MTC) ， narrowband Internet-of-Things (NB-IoT) ， enhanced mobile broadband (eMBB) ， or others) that may provide access for different types of devices. In some cases， the term “cell” may refer to a portion of a geographic coverage area 110 (e.g.， a sector) over which the logical entity operates.

UEs 115 may be dispersed throughout the wireless communications system 100， and each UE 115 may be stationary or mobile. A UE 115 may also be referred to as a mobile device， a wireless device， a remote device， a handheld device， or a subscriber device， or some other suitable terminology， where the “device” may also be referred to as a unit， a station， a terminal， or a client. A UE 115 may also be a personal electronic device such as a cellular phone， a personal digital assistant (PDA) ， a tablet computer， a laptop computer， or a personal computer. In some examples， a UE 115 may also refer to a wireless local loop (WLL) station， an Internet of Things (IoT) device， an Internet of Everything (IoE) device， or an MTC device， or the like， which may be implemented in various articles such as appliances， vehicles， meters， or the like.

Some UEs 115， such as MTC or IoT devices， may be low cost or low complexity devices， and may provide for automated communication between machines (e.g.， via Machine-to-Machine (M2M) communication) . M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station 105 without human intervention. In some examples， M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay that information to a central server or application program that can make use of the information or present the information to humans interacting with the program or application. Some UEs 115 may be designed to collect information or enable automated behavior of machines. Examples of applications for MTC devices include smart metering， inventory monitoring， water level monitoring， equipment monitoring， healthcare monitoring， wildlife monitoring， weather and geological event monitoring， fleet management and tracking， remote security sensing， physical access control， and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reduce power consumption， such as half-duplex communications (e.g.， a mode that supports one-way communication via transmission or reception， but not transmission and reception simultaneously) . In some examples half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for UEs 115 include entering a power saving “deep sleep” mode when not engaging in active communications， or operating over a limited bandwidth (e.g.， according to narrowband communications) . In some cases， UEs 115 may be designed to support critical functions (e.g.， mission critical functions) ， and a wireless communications system 100 may be configured to provide ultra-reliable communications for these functions.

In some cases， a UE 115 may also be able to communicate directly with other UEs 115 (e.g.， using a peer-to-peer (P2P) or device-to-device (D2D) protocol) . One or more of a group of UEs 115 utilizing D2D communications may be within the geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of a base station 105， or be otherwise unable to receive transmissions from a base station 105. In some cases， groups of UEs 115 communicating via D2D communications may utilize a one-to-many (1： M) system in which each UE 115 transmits to every other UE 115 in the group. In some cases， a base station 105 facilitates the scheduling of resources for D2D communications. In other cases， D2D communications are carried out between UEs 115 without the involvement of a base station 105.

Base stations 105 may communicate with the core network 130 and with one another. For example， base stations 105 may interface with the core network 130 through backhaul links 132 (e.g.， via an S1 or other interface) . Base stations 105 may communicate with one another over backhaul links 134 (e.g.， via an X2 or other interface) either directly (e.g.， directly between base stations 105) or indirectly (e.g.， via core network 130) .

The core network 130 may provide user authentication， access authorization， tracking， Internet Protocol (IP) connectivity， and other access， routing， or mobility functions. The core network 130 may be an evolved packet core (EPC) ， which may include at least one mobility management entity (MME) ， at least one serving gateway (S-GW) ， and at least one Packet Data Network (PDN) gateway (P-GW) . The MME may manage non-access stratum (e.g.， control plane) functions such as mobility， authentication， and bearer management for UEs 115 served by base stations 105 associated with the EPC. User IP packets may be transferred through the S-GW， which itself may be connected to the P-GW. The P-GW may provide IP address allocation as well as other functions. The P-GW may be connected to the network operators IP services. The operators IP services may include access to the Internet， Intranet (s) ， an IP Multimedia Subsystem (IMS) ， or a Packet-Switched (PS) Streaming Service.

At least some of the network devices， such as a base station 105， may include subcomponents such as an access network entity， which may be an example of an access node controller (ANC) . Each access network entity may communicate with UEs 115 through a number of other access network transmission entities， which may be referred to as a radio head， a smart radio head， or a transmission/reception point (TRP) . In some configurations， various functions of each access network entity or base station 105 may be distributed across various network devices (e.g.， radio heads and access network controllers) or consolidated into a single network device (e.g.， a base station 105) .

Wireless communications system 100 may operate using one or more frequency bands， typically in the range of 300 MHz to 300 GHz. Generally， the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band， since the wavelengths range from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features. However， the waves may penetrate structures sufficiently for a macro cell to provide service to UEs 115 located indoors. Transmission of UHF waves may be associated with smaller antennas and shorter range (e.g.， less than 100 km) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

Wireless communications system 100 may also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz， also known as the centimeter band. The SHF region includes bands such as the 5 GHz industrial， scientific， and medical (ISM) bands， which may be used opportunistically by devices that can tolerate interference from other users.

Wireless communications system 100 may also operate in an extremely high frequency (EHF) region of the spectrum (e.g.， from 30 GHz to 300 GHz) ， also known as the millimeter band. In some examples， wireless communications system 100 may support millimeter wave (mmW) communications between UEs 115 and base stations 105， and EHF antennas of the respective devices may be even smaller and more closely spaced than UHF antennas. In some cases， this may facilitate use of antenna arrays within a UE 115. However， the propagation of EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. Techniques disclosed herein may be employed across transmissions that use one or more different frequency regions， and designated use of bands across these frequency regions may differ by country or regulating body.

In some cases， wireless communications system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example， wireless communications system 100 may employ License Assisted Access (LAA) ， LTE-Unlicensed (LTE-U) radio access technology， or NR technology in an unlicensed band such as the 5 GHz ISM band. When operating in unlicensed radio frequency spectrum bands， wireless devices such as base stations 105 and UEs 115 may employ listen-before-talk (LBT) procedures to ensure a frequency channel is clear before transmitting data. In some cases， operations in unlicensed bands may be based on a CA configuration in conjunction with CCs operating in a licensed band (e.g.， LAA) . Operations in unlicensed spectrum may include downlink transmissions， uplink transmissions， peer-to-peer transmissions， or a combination of these. Duplexing in unlicensed spectrum may be based on frequency division duplexing (FDD) ， time division duplexing (TDD) ， or a combination of both.

In some examples， base station 105 or UE 115 may be equipped with multiple antennas， which may be used to employ techniques such as transmit diversity， receive diversity， multiple-input multiple-output (MIMO) communications， or beamforming. For example， wireless communications system 100 may use a transmission scheme between a transmitting device (e.g.， a base station 105) and a receiving device (e.g.， a UE 115) ， where the transmitting device is equipped with multiple antennas and the receiving devices are equipped with one or more antennas. MIMO communications may employ multipath signal propagation to increase the spectral efficiency by transmitting or receiving multiple signals via different spatial layers， which may be referred to as spatial multiplexing. The multiple signals may， for example， be transmitted by the transmitting device via different antennas or different combinations of antennas. Likewise， the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream， and may carry bits associated with the same data stream (e.g.， the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) where multiple spatial layers are transmitted to the same receiving device， and multiple-user MIMO (MU-MIMO) where multiple spatial layers are transmitted to multiple devices.

Beamforming， which may also be referred to as spatial filtering， directional transmission， or directional reception， is a signal processing technique that may be used at a transmitting device or a receiving device (e.g.， a base station 105 or a UE 115) to shape or steer an antenna beam (e.g.， a transmit beam or receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that signals propagating at particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference. The adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying certain amplitude and phase offsets to signals carried via each of the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g.， with respect to the antenna array of the transmitting device or receiving device， or with respect to some other orientation) .

In one example， a base station 105 may use multiple antennas or antenna arrays to conduct beamforming operations for directional communications with a UE 115. For instance， some signals (e.g. synchronization signals， reference signals， beam selection signals， or other control signals) may be transmitted by a base station 105 multiple times in different directions， which may include a signal being transmitted according to different beamforming weight sets associated with different directions of transmission. Transmissions in different beam directions may be used to identify (e.g.， by the base station 105 or a receiving device， such as a UE 115) a beam direction for subsequent transmission and/or reception by the base station 105. Some signals， such as data signals associated with a particular receiving device， may be transmitted by a base station 105 in a single beam direction (e.g.， a direction associated with the receiving device， such as a UE 115) . In some examples， the beam direction associated with transmissions along a single beam direction may be determined based at least in in part on a signal that was transmitted in different beam directions. For example， a UE 115 may receive one or more of the signals transmitted by the base station 105 in different directions， and the UE 115 may report to the base station 105 an indication of the signal it received with a highest signal quality， or an otherwise acceptable signal quality. Although these techniques are described with reference to signals transmitted in one or more directions by a base station 105， a UE 115 may employ similar techniques for transmitting signals multiple times in different directions (e.g.， for identifying a beam direction for subsequent transmission or reception by the UE 115) ， or transmitting a signal in a single direction (e.g.， for transmitting data to a receiving device) .

A receiving device (e.g.， a UE 115， which may be an example of a mmW receiving device) may try multiple receive beams when receiving various signals from the base station 105， such as synchronization signals， reference signals， beam selection signals， or other control signals. For example， a receiving device may try multiple receive directions by receiving via different antenna subarrays， by processing received signals according to different antenna subarrays， by receiving according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array， or by processing received signals according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array， any of which may be referred to as “listening” according to different receive beams or receive directions. In some examples a receiving device may use a single receive beam to receive along a single beam direction (e.g.， when receiving a data signal) . The single receive beam may be aligned in a beam direction determined based at least in part on listening according to different receive beam directions (e.g.， a beam direction determined to have a highest signal strength， highest signal-to-noise ratio， or otherwise acceptable signal quality based at least in part on listening according to multiple beam directions) .

In some cases， the antennas of a base station 105 or UE 115 may be located within one or more antenna arrays， which may support MIMO operations， or transmit or receive beamforming. For example， one or more base station antennas or antenna arrays may be co-located at an antenna assembly， such as an antenna tower. In some cases， antennas or antenna arrays associated with a base station 105 may be located in diverse geographic locations. A base station 105 may have an antenna array with a number of rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with a UE 115. Likewise， a UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.

In some cases， wireless communications system 100 may be a packet-based network that operate according to a layered protocol stack. In the user plane， communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may in some cases perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use hybrid automatic repeat request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane， the Radio Resource Control (RRC) protocol layer may provide establishment， configuration， and maintenance of an RRC connection between a UE 115 and a base station 105 or core network 130 supporting radio bearers for user plane data. At the Physical (PHY) layer， transport channels may be mapped to physical channels.

In some cases， UEs 115 and base stations 105 may support retransmissions of data to increase the likelihood that data is received successfully. HARQ feedback is one technique of increasing the likelihood that data is received correctly over a communication link 125. HARQ may include a combination of error detection (e.g.， using a cyclic redundancy check (CRC) ) ， forward error correction (FEC) ， and retransmission (e.g.， automatic repeat request (ARQ) ) . HARQ may improve throughput at the MAC layer in poor radio conditions (e.g.， signal-to-noise conditions) . In some cases， a wireless device may support same-slot HARQ feedback， where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot. In other cases， the device may provide HARQ feedback in a subsequent slot， or according to some other time interval.

Time intervals in LTE or NR may be expressed in multiples of a basic time unit， which may， for example， refer to a sampling period of T_s ＝ 1/30,720,000 seconds. Time intervals of a communications resource may be organized according to radio frames each having a duration of 10 milliseconds (ms) ， where the frame period may be expressed as T_f ＝ 307,200 Ts. The radio frames may be identified by a system frame number (SFN) ranging from 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9， and each subframe may have a duration of 1 ms. A subframe may be further divided into 2 slots each having a duration of 0.5 ms， and each slot may contain 6 or 7 modulation symbol periods (e.g.， depending on the length of the cyclic prefix prepended to each symbol period) . Excluding the cyclic prefix， each symbol period may contain 2048 sampling periods. In some cases a subframe may be the smallest scheduling unit of the wireless communications system 100， and may be referred to as a transmission time interval (TTI) . In other cases， a smallest scheduling unit of the wireless communications system 100 may be shorter than a subframe or may be dynamically selected (e.g.， in bursts of shortened TTIs (sTTIs) or in selected component carriers using sTTIs) .

In some wireless communications systems， a slot may further be divided into multiple mini-slots containing one or more symbols. In some instances， a symbol of a mini-slot or a mini-slot may be the smallest unit of scheduling. Each symbol may vary in duration depending on the subcarrier spacing or frequency band of operation， for example. Further， some wireless communications systems may implement slot aggregation in which multiple slots or mini-slots are aggregated together and used for communication between a UE 115 and a base station 105.

The term “carrier” refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communications over a communication link 125. For example， a carrier of a communication link 125 may include a portion of a radio frequency spectrum band that is operated according to physical layer channels for a given radio access technology. Each physical layer channel may carry user data， control information， or other signaling. A carrier may be associated with a pre-defined frequency channel (e.g.， an E-UTRA absolute radio frequency channel number (EARFCN) ) ， and may be positioned according to a channel raster for discovery by UEs 115. Carriers may be downlink or uplink (e.g.， in an FDD mode) ， or be configured to carry downlink and uplink communications (e.g.， in a TDD mode) . In some examples， signal waveforms transmitted over a carrier may be made up of multiple sub-carriers (e.g.， using multi-carrier modulation (MCM) techniques such as OFDM or DFT-s-OFDM) .

The organizational structure of the carriers may be different for different radio access technologies (e.g.， LTE， LTE-A， NR， etc. ) . For example， communications over a carrier may be organized according to TTIs or slots， each of which may include user data as well as control information or signaling to support decoding the user data. A carrier may also include dedicated acquisition signaling (e.g.， synchronization signals or system information， etc. ) and control signaling that coordinates operation for the carrier. In some examples (e.g.， in a carrier aggregation configuration) ， a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers.

Physical channels may be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed on a downlink carrier， for example， using time division multiplexing (TDM) techniques， frequency division multiplexing (FDM) techniques， or hybrid TDM-FDM techniques. In some examples， control information transmitted in a physical control channel may be distributed between different control regions in a cascaded manner (e.g.， between a common control region or common search space and one or more UE-specific control regions or UE-specific search spaces) .

A carrier may be associated with a particular bandwidth of the radio frequency spectrum， and in some examples the carrier bandwidth may be referred to as a “system bandwidth” of the carrier or the wireless communications system 100. For example， the carrier bandwidth may be one of a number of predetermined bandwidths for carriers of a particular radio access technology (e.g.， 1.4， 3， 5， 10， 15， 20， 40， or 80 MHz) . In some examples， each served UE 115 may be configured for operating over portions or all of the carrier bandwidth. In other examples， some UEs 115 may be configured for operation using a narrowband protocol type that is associated with a predefined portion or range (e.g.， set of subcarriers or RBs) within a carrier (e.g.， “in-band” deployment of a narrowband protocol type) .

In a system employing MCM techniques， a resource element may consist of one symbol period (e.g.， a duration of one modulation symbol) and one subcarrier， where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g.， the order of the modulation scheme) . Thus， the more resource elements that a UE 115 receives and the higher the order of the modulation scheme， the higher the data rate may be for the UE 115. In MIMO systems， a wireless communications resource may refer to a combination of a radio frequency spectrum resource， a time resource， and a spatial resource (e.g.， spatial layers) ， and the use of multiple spatial layers may further increase the data rate for communications with a UE 115.

Devices of the wireless communications system 100 (e.g.， base stations 105 or UEs 115) may have a hardware configuration that supports communications over a particular carrier bandwidth， or may be configurable to support communications over one of a set of carrier bandwidths. In some examples， the wireless communications system 100 may include base stations 105 and/or UEs that can support simultaneous communications via carriers associated with more than one different carrier bandwidth.

Wireless communications system 100 may support communication with a UE 115 on multiple cells or carriers， a feature which may be referred to as carrier aggregation (CA) or multi-carrier operation. A UE 115 may be configured with multiple downlink CCs and one or more uplink CCs according to a carrier aggregation configuration. Carrier aggregation may be used with both FDD and TDD component carriers.

In some cases， wireless communications system 100 may utilize enhanced component carriers (eCCs) . An eCC may be characterized by one or more features including wider carrier or frequency channel bandwidth， shorter symbol duration， shorter TTI duration， or modified control channel configuration. In some cases， an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g.， when multiple serving cells have a suboptimal or non-ideal backhaul link) . An eCC may also be configured for use in unlicensed spectrum or shared spectrum (e.g.， where more than one operator is allowed to use the spectrum) . An eCC characterized by wide carrier bandwidth may include one or more segments that may be utilized by UEs 115 that are not capable of monitoring the whole carrier bandwidth or are otherwise configured to use a limited carrier bandwidth (e.g.， to conserve power) .

In some cases， an eCC may utilize a different symbol duration than other CCs， which may include use of a reduced symbol duration as compared with symbol durations of the other CCs. A shorter symbol duration may be associated with increased spacing between adjacent subcarriers. A device， such as a UE 115 or base station 105， utilizing eCCs may transmit wideband signals (e.g.， according to frequency channel or carrier bandwidths of 20， 40，60， 80 MHz， etc. ) at reduced symbol durations (e.g.， 16.67 microseconds) . A TTI in eCC may consist of one or multiple symbol periods. In some cases， the TTI duration (that is， the number of symbol periods in a TTI) may be variable.

Wireless communications systems such as an NR system may utilize any combination of licensed， shared， and unlicensed spectrum bands， among others. The flexibility of eCC symbol duration and subcarrier spacing may allow for the use of eCC across multiple spectrums. In some examples， NR shared spectrum may increase spectrum utilization and spectral efficiency， specifically through dynamic vertical (e.g.， across frequency) and horizontal (e.g.， across time) sharing of resources.

FIG. 2 illustrates an example of a device 200 that supports encoding and decoding for messages with partial common content in accordance with various aspects of the present disclosure. The device 200 may be any device within wireless communications system 100 that performs an encoding or decoding operation. The device 200 may be， for example， a UE 115 or base station 105 as described in FIG. 1.

As shown， device 200 may include a memory 205， an encoder/decoder 210， and a transmitter/receiver 215. Bus 220 may connect memory 205 to encoder/decoder 210 and bus 225 may connect encoder/decoder 210 to transmitter/receiver 215. In some instances， device 200 may have data stored in memory 205 to be transmitted to another device， such as UE 115 or base station 105. Additionally or alternatively， memory 205 may store data received in one or more transmissions from another device. To initiate the encoding or decoding process， the device 200 may retrieve from memory 205 the data for processing. The data may include a number (e.g.， K) of bits provided from memory 205 to encoder/decoder 210 via bus 220. The encoder/decoder 210 may process these bits using a linear block code， for example， to obtain M bits for transmission， where generally M＞K to provide coding gain.

Device 200 may support use of one or more linear codes. Linear codes are characterized by the property that the modulo-2 addition of any two codewords that are generated by applying the encoding operation to respective input vectors equals the codeword generated by applying the encoding operation to the combination of the input vectors. Expressed mathematically， f (A) +f( B) ＝f (A+B) for any two input vectors A， B where f () conveys application of the encoding operation. Examples of linear codes include convolutional codes， Turbo codes， low density parity check (LDPC) codes， polar codes， cyclic redundancy check (CRC) codes， etc. It is to be understood that the foregoing is not an exhaustive list and that some of these example linear codes may be combined (e.g.， a CRC-appended polar code) . Encoder/decoder 210 may use a number of encoding techniques to encode the data for transmission such as linear block encoding， polar encoding， Reed-Muller (RM) encoding， polar RM encoding， and the like， which may introduce redundancy into the encoded output. This redundancy or coding gain may increase the overall probability that the number of information bits will be successfully decoded upon reception.

FIG. 3 illustrates an example of a process flow 300 that supports encoding for messages with partial common content in accordance with various aspects of the present disclosure. In some examples， process flow 300 may be implemented by aspects of wireless communication system 100. For example， process flow 300 may be implemented by a wireless device (e.g.， device 200 described with reference to FIG. 2) such as a base station 105.

Process flow 300 includes variable data 305 and fixed data 310， examples of which are provided in the context of timing information and static (e.g.， or semi-static) system information， respectively. The variable data 305 and fixed data 310 may be examples of input vectors to an encoding operation as described with reference to FIG. 2. Variable data 305 and fixed data 310 may each be fed to an encoding operation 315， which may apply a linear coding operation as described above. As illustrated， the variable data 305 may be fed to a first set of input positions 320 (e.g.， three input positions 320 in the present example) while the fixed data 310 may be fed to a second set of input positions 320 (e.g.， five input positions 320) . It is to be understood that these numbers are chosen arbitrarily for the sake of illustration and are not limiting of scope (e.g.， such that each input vector may be fed to any suitable number of input positions 320) . In some cases， the first set of input positions 320 and the second set of input positions 320 may be disjoint (e.g.， may not share any input positions 320) as illustrated. In aspects， the input vectors of variable data 305 and/or fixed data 310 may be extended (e.g.， through zero-padding or some other suitable technique) such that the length of each input vector fed to the encoding operation 315 is the same. That is， in the case that the encoding operation 315 accepts sixty-four input bits and each input vector contains fewer than sixty-four bits， the input vectors may have zeroes appended until each has a length of sixty-four bits.

In aspects of the present disclosure， the output of encoding operation 315 may be referred to as a component codeword 325. For example， application of encoding operation 315 to fixed data 310 may generate component codeword 325-b. Similarly， application of encoding operation 315 to any suitable number of input vectors of variable data 305 (e.g.， four in the present example) may generate a corresponding number of component codewords 325-a. Because of the linearity of encoding operation 315， component codeword 325-b may be combined with each component codeword 325-a (e.g.， using modulo-2 addition as illustrated by XOR operator 330) to generate a corresponding number of codewords 335 for transmission. It is to be understood that the four codewords 335 may alternatively be generated by concatenating each input vector of the variable data 305 with the input vector of the fixed data 310 before applying encoding operation 315 (e.g.， based on the linear nature of the encoding operation 315) . However， such techniques may negatively impact the efficiency of the encoding operation 315 because of the redundancy introduced by encoding the fixed data 310 for each codeword 335.

Accordingly， each codeword 335 may be said to comprise a fixed (e.g.， or common) portion and a variable portion. Aspects of the present disclosure consider encoding techniques that improve coding gain (e.g.， by minimizing or reducing the decoding error rate of the variable portion) . For example， the coding gain may be improved by allocating the variable portion to input positions 320 of the encoding operation 315 that are more reliable. In some cases (e.g.， in the case of polar codes) ， the variable portion may additionally or alternatively be assigned to input positions based at least in part on an associated decoding order. The decoding order and reliability may be correlated (e.g.， such that the more reliable input positions may generally correspond to positions that are later in the decoding order) ， but may not be the same in all cases.

Additionally or alternatively， coding gain improvements may be achieved through the use of differential encoding of the variable portions (e.g.， the time index bits) . For example， to generate the variable data 305， a given set of time index bits (e.g.， which may correspond to a subframe number or any other suitable time information) may first be encoded with additional redundant bits to make the difference of any two consecutive indices unique. Such techniques may support aspects of the decoding operations discussed below. By way of example， Table 1 illustrates a codebook for a 1-bit time index， Table 2 illustrates a codebook for a 2-bit time index， and Table 3 illustrates a codebook for a 3-bit time index. It is to be understood that these tables are included for illustrative purposes and are not necessarily limiting of scope.

Table 1： Codebook of 1-Bit Time Index

Time Index	Coded Bits	Differential
0	00	00
1	01	01
0	10	11
1	11	01

Table 2： Codebook of 2-Bit Time Index

Time Index	Coded Bits	Differential
0	000	011
1	001	001
2	110	111
3	011	101

Table 3： Codebook of 3-Bit Time Index

Time Index	Coded Bits	Differential
0	0000	0111
1	0001	0001
2	0010	0011
3	0100	0110
4	1011	1111

5	0101	1110
6	1110	1011
7	0111	1001

With respect to Table 2， the differential for time index 1 (i.e.， ‘001’ ) refers to the modulo-2 difference (i.e.， the XOR result) between the coded bits for time index 0 (i.e.， ‘000’ ) and the coded bits for time index 1 (i.e.， ‘001’ ) . Similarly， the differential for time index 2 (i.e.， ‘111’ ) refers to the result of applying the XOR operation to the coded bits for time index 1 (i.e.， ‘001’ ) and the coded bits for time index 2 (i.e.， ‘110’ ) . Analogous properties extend to the coded bits of Table 1 and Table 3. By making the differential of every two consecutive time indices unique， the time index of the most recently received codeword 335 may be obtained directly using techniques described below. It is to be understood that the properties used to develop the codebooks described above may be extended to accommodate various scenarios. For example， the codebook may be designed so that the difference between time indices separated by N other time indices are unique (e.g.， to support scenarios in which a receiver may operate in a discontinuous reception (DRX) mode) .

In some examples， the variable data 305 may include an error check value for a variable payload and the fixed data 310. For example， the variable data may include a variable payload such as time index bits and a CRC value generated from the time index bits and the fixed data 310.

FIG. 4 illustrates an example of a process flow 400 that supports decoding for messages with partial common content in accordance with various aspects of the present disclosure. In some examples， process flow 400 may implement aspects of wireless communication system 100. For example， process flow 400 may be implemented by a wireless device (e.g.， device 200 described with reference to FIG. 2) such as a UE 115.

Process flow 400 includes codewords 405-a， 405-b， which may be example of the codewords 335 described with reference to FIG. 3. That is， codewords 405-a， 405-b may share common content (e.g.， fixed data 310) and may each contain respective variable content (e.g.， variable data 305) . For example， codeword 405-amay be received in a first time interval and may have a variable portion corresponding to the first time interval while codeword 405-b may be received in a second time interval and may have a variable portion corresponding to the second time interval. As described above， it may be possible to achieve a soft combination of codewords 405-a， 405-b based on multiple hypotheses of possible combinations of the respective variable portions； however， such a decoding design may inflate the undetected error rate (e.g.， because it may increase the number of tested hypotheses for the codeword， increasing the probability that one or more of the multiple hypotheses may pass a CRC even though it corresponds to an invalid decoding hypothesis) .

Aspects of the present disclosure may support differential decoding before soft-combining. For example， codewords 405-a， 405-b may be fed to an XOR operator 410， which may perform an XOR on the LLR-domain representations of the codewords 405. Based on the properties of the XOR operation， XOR operator 410 may remove the effect of the common parts from the codewords 405 and generate an LLR-domain differential (e.g.， which may alternatively be referred to as a “difference” or a “difference vector” in aspects of the present disclosure) . In various aspects， the operations of XOR operator 410 may be referred to as F-operations (e.g.， for a polar decoder) ， check node operations (e.g.， for an LDPC decoder) ， etc. Mathematically， the LLR-domain XOR operation between two values A and B of different codewords 405 may be represented as：

The difference vector may be fed to a decoder at 415， which may decode the difference of the variable portions (e.g.， to generate a decoding candidate for the difference vector) . As described above with reference to Tables 1， 2， and 3， the variable portions may be encoded such that the differences between time indices of successive codewords 405 may be unique. This property may allow the receiver to identify the time index (e.g.， of codeword 405-b) based solely on decoding the difference between codeword 405-aand codeword 405-b. Accordingly， in cases in which the receiver is only interested in the content of the variable portion (e.g.， because it has previously decoded the content of the fixed portion or otherwise considers the fixed portion extraneous) ， the device may exit process flow 400 at 420 upon generating the decoding candidate at 415. In some examples， generating the decoding candidate at 415 may include running an error check on the difference between codeword 405-aand codeword 405-b. The linear nature of an error check function may be used to perform the same error check on a difference between the codewords to determine if any candidate paths of the decoded differential codeword pass the error check function. The error check function may be， for example， a CRC operation.

Additionally or alternatively， process flow 400 may continue by re-encoding the decoding candidate at 425 to produce a candidate variable component codeword. For example， the difference generated by XOR operator 410 (e.g.， which may be in the LLR-domain) may be transformed to a bit representation by the decoding at 415， and this bit representation may serve as an input vector to an encoding operation as described with reference to FIG. 3. For example， the encoding operation may be the same encoding operation used to generate codewords 405-a， 405-b. Subsequently， at 430， the candidate variable component codeword and codeword 405-amay be fed to an XOR operator 430 (e.g.， which may be distinct from XOR operator 410 by virtue of the fact that XOR operator 410 operates completely in the LLR domain and XOR operator 430 does not) . For example， XOR operator 430 may apply the candidate variable component codeword to the LLR-domain representation of codeword 405-a (e.g.， may flip the LLR signs of codeword 405-aaccording to the corresponding bit values of the candidate variable component codeword) . Such operations may generate a hypothesized second version of codeword 405-b， which may be combined with the received version of codeword 405-b at 435 and fed to a linear decoding operation at 440.

It is to be understood that while the above example is described in the context of two codewords 405， the techniques may be extended to any suitable number of codewords 405. For example， in the case of three codewords 405， process flow 400 may be performed two times， once to convert the first codeword to a first hypothesized version of the second codeword and again to convert the third codeword to a second hypothesized version of the second codeword； the three versions of the second codeword (i.e.， the received second codeword and the two hypothesized versions) may then be soft-combined. Briefly， in the case of a fourth codeword， the fourth codeword may first be converted to a hypothesized version of the third codeword， and this hypothesized version may then be converted to a hypothesized version of the second codeword and included in the soft-combination， and so on.

FIGs. 5A and 5B illustrate

example encoding configurations

500， 550 that support encoding and decoding for messages with partial common content in accordance with various aspects of the present disclosure. In some examples， encoding

configurations

500， 550 may support aspects of wireless communication system 100. For example， encoding

configurations

500， 550 may illustrate bit allocations for a linear encoding operation that support increased coding gain. Because of the nature of the transmissions discussed above (e.g.， in which a fixed portion is transmitted a plurality of times in a given set of codewords and each variable portion is transmitted once) ， coding gain may be increased by assigning the bits corresponding to the variable portion to a nested sub-code of the original code. For example， in the case of a polar code， the variable bits 515 may be allocated to bit positions that are later in a decoding order (e.g.， as illustrated with respect to encoding configuration 500) and/or that are associated with a higher reliability (e.g.， as illustrated with reference to encoding configuration 550) .

A polar code is an example of a linear block error correcting code used to increase the probability of a successful transmission and has been shown to asymptotically approach channel capacity as the length N of the code increases. During decoding， a decoder may load bits to be decoded onto respective logical bit channels (e.g.， decoding branches) . Bits to be decoded may include unpolarized bits in the received codeword， which the decoder processes to obtain information bits and non-information bits (e.g.， frozen bits 505， parity bits， etc. ) .Because polar codes rely on computing the LLRs for each bit-channel as the channels are polarized towards the input of the code， the decoding process may be iterative and have a strong run-time data dependency. The position of information bits (e.g.， which may include fixed bits 510 and variable bits 515) may depend on reliability metrics calculated based on bit locations (e.g.， channel instances) of the encoder or decoder. For example， the probability that a given bit location will be successfully decoded may be calculated. This probability may be referred to as a reliability and may be associated with the given bit location or channel instance.

Such implementations may be complex， and may introduce latency into the encoding or decoding process. For example， a decoder may perform a blind decoding operation on a control channel where multiple hypotheses of the code length N and dimension m are tested using the decoder. For each hypothesis of different N， the decoder may calculate LLRs through the layers of the code to generate LLRs associated with the input vector， then obtain multiple paths (e.g.， for a list decoder) having the best path metrics through the input vector LLRs， finally testing each against an error checking code (e.g.， CRC) to determine if any of the paths for each hypothesis contain information for the decoder. Techniques described herein may be used to decrease the latency while maintaining benefits of the improved opportunity for coding gain provided by the polar code.

For example， the described techniques may allow a decoder to avoid hypothesis testing when performing soft-combination (e.g.， which may reduce the total decoding computational complexity) . Further， by designing the code into a nested structure， the error rate of the differential variable bits may be lower than that of a payload as a whole (e.g.， which may allow the proposed two-step differential decoding operation to have no significant performance deterioration. Additionally， by encoding the variable part with a few redundant bits， the differential value of every two consecutive time indices may be unique such that a given time index may be derived directly from the first step of the two-step decoding process (e.g.， such that the second step may not be required in all scenarios) . Additional benefits of the described techniques will be apparent to those of skill in the art.

FIG. 6 illustrates an example of a process flow 600 that supports encoding and decoding for messages with partial common content in accordance with various aspects of the present disclosure. In some examples， process flow 600 may implement aspects of wireless communication system 100. Process flow 600 includes a transmitter 605 and a receiver 610， each of which may be an example of any of the wireless devices described above. For example， transmitter 605 may be an example of a base station 105 and receiver 610 may be an example of a UE 115.

At 615， the transmitter 605 may apply an encoding operation to a first input vector corresponding to a fixed portion of data to generate a fixed component codeword to be used for a plurality of codewords transmitted in a plurality of corresponding time intervals. For example， the encoding operation may be a linear encoding operation and the fixed portion may correspond to a portion of a PBCH payload.

At 620， transmitter 605 may apply the encoding operation to a first variable input vector to generate a first variable component codeword. For example， the first variable input vector may include a bit stream corresponding to a SFN of the corresponding time interval. In some cases， the first input vector corresponding to the fixed portion of data is associated with a first set of bit positions of the encoding operation having a first decoding error rate and the variable input vector is associated with a second set of bit positions of the encoding operation having a second decoding error rate lower than the first decoding error rate. In some cases， the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of highest reliability bit channels and/or a set of terminal positions in a decoding order of the polar code. In some cases， the variable input vector includes a plurality of error detecting bits (e.g.， CRC bits) covering the SFN and the payload of the first input vector.

At 625， transmitter 605 may combine the fixed component codeword and first variable component codeword to generate a first codeword (e.g.， which may be enabled based on the linear nature of the encoding operation applied at 615 and 620) . Transmitter 605 may transmit the first codeword at 630 in a corresponding time interval (e.g.， a time interval corresponding to the SFN included in the first variable input vector) . Similarly， transmitter may apply the encoding operation to a second variable input vector at 635 to generate a second variable component codeword. Transmitter 605 may combine the fixed component codeword and second variable component codeword at 640 to generate a second codeword， which may be transmitted at 645 in a corresponding time interval. In some cases， the first and second variable input vectors may each comprise a respective coded sequence developed such that a difference between any coded sequences that correspond to adjacent time intervals are distinct from any other difference between coded sequences corresponding to other adjacent time intervals.

Receiver 610 may receive the first and second codewords at 630 and 645， respectively. At 650， receiver 610 may identify a difference between the first and second codewords. For example， receiver 610 may perform a LLR-domain XOR operation between codeword values of each bit position of the first and second codewords as described with reference to FIG. 4. In some cases， receiver 610 may decode the difference to obtain at least one of the first variable portion or the second variable portion.

In some cases， receiver 610 may optionally apply the difference to the first codeword to obtain a hypothesized second codeword at 655. For example， receiver 610 may decode the difference (e.g.， which may alternatively be referred to as a difference vector) to generate a decoding candidate， re-encode the decoding candidate to produce a candidate variable component codeword， and perform a LLR XOR operation between codeword values for each bit position of the first codeword and the candidate variable component codeword. At 660， receiver 610 may optionally combine the second codeword and the hypothesized second codeword to obtain a combined codeword and perform a decoding operation on the combined codeword. While the above example is described in the context of two codewords， it is to be understood that the described techniques may be extended to any suitable number of codewords.

FIG. 7 shows a block diagram 700 of a wireless device 705 that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. Wireless device 705 may be an example of aspects of a base station 105 or a device 200 as described herein. Wireless device 705 may include receiver 710， base station communications manager 715， and transmitter 720. Wireless device 705 may also include a processor. Each of these components may be in communication with one another (e.g.， via one or more buses) .

Receiver 710 may receive information such as packets， user data， or control information associated with various information channels (e.g.， control channels， data channels， and information related to encoding and decoding for messages with partial common content， etc. ) . Information may be passed on to other components of the device. The receiver 710 may be an example of aspects of the transceiver 1035 described with reference to FIG. 10. The receiver 710 may utilize a single antenna or a set of antennas.

Base station communications manager 715 may be an example of aspects of the base station communications manager 1015 described with reference to FIG. 10. Base station communications manager 715 and/or at least some of its various sub-components may be implemented in hardware， software executed by a processor， firmware， or any combination thereof. If implemented in software executed by a processor， the functions of the base station communications manager 715 and/or at least some of its various sub-components may be executed by a general-purpose processor， a digital signal processor (DSP) ， an application-specific integrated circuit (ASIC) ， an field-programmable gate array (FPGA) or other programmable logic device， discrete gate or transistor logic， discrete hardware components， or any combination thereof designed to perform the functions described in the present disclosure.

The base station communications manager 715 and/or at least some of its various sub-components may be physically located at various positions， including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples， base station communications manager 715 and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples， base station communications manager 715 and/or at least some of its various sub-components may be combined with one or more other hardware components， including but not limited to an I/O component， a transceiver， a network server， another computing device， one or more other components described in the present disclosure， or a combination thereof in accordance with various aspects of the present disclosure.

Base station communications manager 715 may apply an encoding operation to a first input vector to generate a first component codeword to be used for a set of codewords transmitted in a set of corresponding time intervals. Base station communications manager 715 may apply the encoding operation to a set of second input vectors to generate a respective set of second component codewords. Base station communications manager 715 may combine， for each of the set of codewords， the first component codeword with a respective second component codeword. Base station communications manager 715 may transmit the set of codewords in the set of corresponding time intervals.

Transmitter 720 may transmit signals generated by other components of the device. In some examples， the transmitter 720 may be collocated with a receiver 710 in a transceiver module. For example， the transmitter 720 may be an example of aspects of the transceiver 1035 described with reference to FIG. 10. The transmitter 720 may utilize a single antenna or a set of antennas.

FIG. 8 shows a block diagram 800 of a wireless device 805 that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. Wireless device 805 may be an example of aspects of a wireless device 705 or a base station 105 as described with reference to FIG. 7. Wireless device 805 may include receiver 810， base station communications manager 815， and transmitter 820. Wireless device 805 may also include a processor. Each of these components may be in communication with one another (e.g.， via one or more buses) .

Receiver 810 may receive information such as packets， user data， or control information associated with various information channels (e.g.， control channels， data channels， and information related to encoding and decoding for messages with partial common content， etc. ) . Information may be passed on to other components of the device. The receiver 810 may be an example of aspects of the transceiver 1035 described with reference to FIG. 10. The receiver 810 may utilize a single antenna or a set of antennas.

Base station communications manager 815 may be an example of aspects of the base station communications manager 1015 described with reference to FIG. 10. Base station communications manager 815 may also include encoder 825， codeword combiner 830， and transmission controller 835.

Encoder 825 may apply an encoding operation to a first input vector to generate a first component codeword to be used for a set of codewords transmitted in a set of corresponding time intervals and apply the encoding operation to a set of second input vectors to generate a respective set of second component codewords. In some cases， each second input vector includes a respective coded sequence， where a difference between any coded sequences that correspond to adjacent time intervals is distinct from any other difference between coded sequences corresponding to adjacent time intervals. In some cases， the first input vector is associated with a first set of bit positions of the encoding operation having a first decoding error rate and each second input vector is associated with a second set of bit positions of the encoding operation having a second decoding error rate lower than the first decoding error rate.

In some cases， the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of highest reliability bit channels. In some cases， the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar code. In some cases， each of the set of second input vectors includes a bit stream corresponding to a respective SFN. In some cases， each of the set of second input vectors includes a respective set of error detecting check bits covering the respective SFN and a payload of the first input vector. In some cases， each of the set of codewords includes a PBCH. In some cases， the encoding operation is a linear encoding operation.

Codeword combiner 830 may combine， for each of the set of codewords， the first component codeword with a respective second component codeword. Transmission controller 835 may transmit the set of codewords in the set of corresponding time intervals.

Transmitter 820 may transmit signals generated by other components of the device. In some examples， the transmitter 820 may be collocated with a receiver 810 in a transceiver module. For example， the transmitter 820 may be an example of aspects of the transceiver 1035 described with reference to FIG. 10. The transmitter 820 may utilize a single antenna or a set of antennas.

FIG. 9 shows a block diagram 900 of a base station communications manager 915 that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. The base station communications manager 915 may be an example of aspects of a base station communications manager 715， a base station communications manager 815， or a base station communications manager 1015 described with reference to FIGs. 7， 8， and 10. The base station communications manager 915 may include encoder 920， codeword combiner 925， and transmission controller 930. Each of these modules may communicate， directly or indirectly， with one another (e.g.， via one or more buses) .

Encoder 920 may apply an encoding operation to a first input vector to generate a first component codeword to be used for a set of codewords transmitted in a set of corresponding time intervals and apply the encoding operation to a set of second input vectors to generate a respective set of second component codewords. In some cases， each second input vector includes a respective coded sequence， where a difference between any coded sequences that correspond to adjacent time intervals is distinct from any other difference between coded sequences corresponding to adjacent time intervals. In some cases， the first input vector is associated with a first set of bit positions of the encoding operation having a first decoding error rate and each second input vector is associated with a second set of bit positions of the encoding operation having a second decoding error rate lower than the first decoding error rate. In some cases， the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of highest reliability bit channels.

In some cases， the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar code. In some cases， each of the set of second input vectors includes a bit stream corresponding to a respective SFN. In some cases， each of the set of second input vectors includes a respective set of error detecting check bits covering the respective SFN and a payload of the first input vector. In some cases， each of the set of codewords includes a PBCH. In some cases， the encoding operation includes a linear encoding operation.

Codeword combiner 925 may combine， for each of the set of codewords， the first component codeword with a respective second component codeword. Transmission controller 930 may transmit the set of codewords in the set of corresponding time intervals.

FIG. 10 shows a diagram of a system 1000 including a device 1005 that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. Device 1005 may be an example of or include the components of wireless device 705， wireless device 805， or a base station 105 as described above， e.g.， with reference to FIGs. 7 and 8. Device 1005 may include components for bi-directional voice and data communications including components for transmitting and receiving communications， including base station communications manager 1015， processor 1020， memory 1025， software 1030， transceiver 1035， antenna 1040， network communications manager 1045， and inter-station communications manager 1050. These components may be in electronic communication via one or more buses (e.g.， bus 1010) . Device 1005 may communicate wirelessly with one or more UEs 115.

Processor 1020 may include an intelligent hardware device， (e.g.， a general-purpose processor， a DSP， a central processing unit (CPU) ， a microcontroller， an ASIC， an FPGA， a programmable logic device， a discrete gate or transistor logic component， a discrete hardware component， or any combination thereof) . In some cases， processor 1020 may be configured to operate a memory array using a memory controller. In other cases， a memory controller may be integrated into processor 1020. Processor 1020 may be configured to execute computer-readable instructions stored in a memory to perform various functions (e.g.， functions or tasks supporting encoding and decoding for messages with partial common content) .

Memory 1025 may include random access memory (RAM) and read only memory (ROM) . The memory 1025 may store computer-readable， computer-executable software 1030 including instructions that， when executed， cause the processor to perform various functions described herein. In some cases， the memory 1025 may contain， among other things， a basic input/output system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

Software 1030 may include code to implement aspects of the present disclosure， including code to support encoding and decoding for messages with partial common content. Software 1030 may be stored in a non-transitory computer-readable medium such as system memory or other memory. In some cases， the software 1030 may not be directly executable by the processor but may cause a computer (e.g.， when compiled and executed) to perform functions described herein.

Transceiver 1035 may communicate bi-directionally， via one or more antennas， wired， or wireless links as described above. For example， the transceiver 1035 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1035 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission， and to demodulate packets received from the antennas. In some cases， the wireless device may include a single antenna 1040. However， in some cases the device may have more than one antenna 1040， which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

Network communications manager 1045 may manage communications with the core network (e.g.， via one or more wired backhaul links) . For example， the network communications manager 1045 may manage the transfer of data communications for client devices， such as one or more UEs 115.

Inter-station communications manager 1050 may manage communications with other base station 105， and may include a controller or scheduler for controlling communications with UEs 115 in cooperation with other base stations 105. For example， the inter-station communications manager 1050 may coordinate scheduling for transmissions to UEs 115 for various interference mitigation techniques such as beamforming or joint transmission. In some examples， inter-station communications manager 1050 may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations 105.

FIG. 11 shows a block diagram 1100 of a wireless device 1105 that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. Wireless device 1105 may be an example of aspects of a UE 115 or a device 200 as described herein. Wireless device 1105 may include receiver 1110， UE communications manager 1115， and transmitter 1120. Wireless device 1105 may also include a processor. Each of these components may be in communication with one another (e.g.， via one or more buses) .

Receiver 1110 may receive information such as packets， user data， or control information associated with various information channels (e.g.， control channels， data channels， and information related to encoding and decoding for messages with partial common content， etc. ) . Information may be passed on to other components of the device. The receiver 1110 may be an example of aspects of the transceiver 1435 described with reference to FIG. 14. The receiver 1110 may utilize a single antenna or a set of antennas.

UE communications manager 1115 may be an example of aspects of the UE communications manager 1415 described with reference to FIG. 14. UE communications manager 1115 and/or at least some of its various sub-components may be implemented in hardware， software executed by a processor， firmware， or any combination thereof. If implemented in software executed by a processor， the functions of the UE communications manager 1115 and/or at least some of its various sub-components may be executed by a general-purpose processor， a DSP， an ASIC， an FPGA or other programmable logic device， discrete gate or transistor logic， discrete hardware components， or any combination thereof designed to perform the functions described in the present disclosure.

The UE communications manager 1115 and/or at least some of its various sub-components may be physically located at various positions， including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples， UE communications manager 1115 and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples， UE communications manager 1115 and/or at least some of its various sub-components may be combined with one or more other hardware components， including but not limited to an I/O component， a transceiver， a network server， another computing device， one or more other components described in the present disclosure， or a combination thereof in accordance with various aspects of the present disclosure.

UE communications manager 1115 may receive a first codeword generated from a first input vector including a first set of variable bits and a set of fixed bits. UE communications manager 1115 may receive a second codeword generated from a second input vector including a second set of variable bits and the set of fixed bits. UE communications manager 1115 may identify a difference between the first codeword and the second codeword. UE communications manager 1115 may decode the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits. UE communications manager 1115 may also apply a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword， combine the second codeword and the hypothesized second codeword to obtain a combined codeword， and perform a decoding operation on the combined codeword to obtain a representation of the second input vector.

Transmitter 1120 may transmit signals generated by other components of the device. In some examples， the transmitter 1120 may be collocated with a receiver 1110 in a transceiver module. For example， the transmitter 1120 may be an example of aspects of the transceiver 1435 described with reference to FIG. 14. The transmitter 1120 may utilize a single antenna or a set of antennas.

FIG. 12 shows a block diagram 1200 of a wireless device 1205 that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. Wireless device 1205 may be an example of aspects of a wireless device 1105 or a UE 115 as described with reference to FIG. 11. Wireless device 1205 may include receiver 1210， UE communications manager 1215， and transmitter 1220. Wireless device 1205 may also include a processor. Each of these components may be in communication with one another (e.g.， via one or more buses) .

Receiver 1210 may receive information such as packets， user data， or control information associated with various information channels (e.g.， control channels， data channels， and information related to encoding and decoding for messages with partial common content， etc. ) . Information may be passed on to other components of the device. The receiver 1210 may be an example of aspects of the transceiver 1435 described with reference to FIG. 14. The receiver 1210 may utilize a single antenna or a set of antennas.

UE communications manager 1215 may be an example of aspects of the UE communications manager 1415 described with reference to FIG. 14. UE communications manager 1215 may also include monitoring component 1225， differential identifier 1230， decoder 1235， differential applier 1240， and combining component 1245.

Monitoring component 1225 may receive a first codeword generated from a first input vector including a first set of variable bits and a set of fixed bits， receive a second codeword generated from a second input vector including a second set of variable bits and the set of fixed bits， and receive a third codeword generated from a third input vector including a third set of variable bits and the set of fixed bits. In some cases， the first set of variable bits includes a first variable payload and a first set of error detecting check bits covering the first variable payload and the set of fixed bits. In some cases， the first variable payload includes a SFN. In some cases， each of the first and second codewords includes a PBCH.

Differential identifier 1230 may identify a difference between the first codeword and the second codeword. In some cases， identifying the difference includes performing a LLR XOR operation between codeword values for each bit position of the first and second codewords.

Decoder 1235 may decode the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits， perform a decoding operation on the combined codeword to obtain a representation of the second input vector， and perform the decoding operation on the second combined codeword to obtain a second representation of the second input vector. In some cases， the set of fixed bits is associated with a first set of bit positions of a decoding operation having a first decoding error rate and a respective set of variable bits is associated with a second set of bit positions of the decoding operation having a second decoding error rate lower than the first decoding error rate. In some cases， the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of highest reliability bit channels. In some cases， the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar decoding operation. In some cases， applying the difference between the first codeword and the second codeword includes decoding a difference vector to generate a decoding candidate.

Differential applier 1240 may apply a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword and apply a difference between the third codeword and the second codeword to the third codeword to obtain a second hypothesized second codeword. Combining component 1245 may combine the second codeword and the hypothesized second codeword to obtain a combined codeword.

Transmitter 1220 may transmit signals generated by other components of the device. In some examples， the transmitter 1220 may be collocated with a receiver 1210 in a transceiver module. For example， the transmitter 1220 may be an example of aspects of the transceiver 1435 described with reference to FIG. 14. The transmitter 1220 may utilize a single antenna or a set of antennas.

FIG. 13 shows a block diagram 1300 of a UE communications manager 1315 that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. The UE communications manager 1315 may be an example of aspects of a UE communications manager 1415 described with reference to FIGs. 11，12， and 14. The UE communications manager 1315 may include monitoring component 1320， differential identifier 1325， decoder 1330， differential applier 1335， combining component 1340， combinator 1345， re-encoding component 1350， and comparator 1355. Each of these modules may communicate， directly or indirectly， with one another (e.g.， via one or more buses) .

Monitoring component 1320 may receive a first codeword generated from a first input vector including a first set of variable bits and a set of fixed bits， receive a second codeword generated from a second input vector including a second set of variable bits and the set of fixed bits， and receive a third codeword generated from a third input vector including a third set of variable bits and the set of fixed bits. In some cases， the first set of variable bits includes a first variable payload and a first set of error detecting check bits covering the first variable payload and the set of fixed bits. In some cases， the first variable payload includes a SFN. In some cases， each of the first and second codewords includes a PBCH.

Differential identifier 1325 may identify a difference between the first codeword and the second codeword. In some cases， identifying the difference includes performing a LLR XOR operation between codeword values for each bit position of the first and second codewords.

Decoder 1330 may decode the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits， perform a decoding operation on the combined codeword to obtain a representation of the second input vector， and perform the decoding operation on the second combined codeword to obtain a second representation of the second input vector. In some cases， the set of fixed bits is associated with a first set of bit positions of a decoding operation having a first decoding error rate and a respective set of variable bits is associated with a second set of bit positions of the decoding operation having a second decoding error rate lower than the first decoding error rate. In some cases， the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of highest reliability bit channels. In some cases， the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar decoding operation. In some cases， applying the difference between the first codeword and the second codeword includes decoding a difference vector to generate a decoding candidate.

Differential applier 1335 may apply a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword and apply a difference between the third codeword and the second codeword to the third codeword to obtain a second hypothesized second codeword. Combining component 1340 may combine the second codeword and the hypothesized second codeword to obtain a combined codeword. Combinator 1345 may combine the second codeword， the hypothesized second codeword， and the second hypothesized second codeword to obtain a second combined codeword. Re-encoding component 1350 may re-encode the decoding candidate to produce a candidate variable component codeword. Comparator 1355 may perform a LLR XOR operation between codeword values for each bit position of the first codeword and the candidate variable component codeword.

FIG. 14 shows a diagram of a system 1400 including a device 1405 that supports encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. Device 1405 may be an example of or include the components of UE 115 as described above， e.g.， with reference to FIG. 1. Device 1405 may include components for bi-directional voice and data communications including components for transmitting and receiving communications， including UE communications manager 1415， processor 1420， memory 1425， software 1430， transceiver 1435， antenna 1440， and I/O controller 1445. These components may be in electronic communication via one or more buses (e.g.， bus 1410) . Device 1405 may communicate wirelessly with one or more base stations 105.

Processor 1420 may include an intelligent hardware device， (e.g.， a general-purpose processor， a DSP， a CPU， a microcontroller， an ASIC， an FPGA， a programmable logic device， a discrete gate or transistor logic component， a discrete hardware component， or any combination thereof) . In some cases， processor 1420 may be configured to operate a memory array using a memory controller. In other cases， a memory controller may be integrated into processor 1420. Processor 1420 may be configured to execute computer-readable instructions stored in a memory to perform various functions (e.g.， functions or tasks supporting encoding and decoding for messages with partial common content) .

Memory 1425 may include RAM and ROM. The memory 1425 may store computer-readable， computer-executable software 1430 including instructions that， when executed， cause the processor to perform various functions described herein. In some cases， the memory 1425 may contain， among other things， a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices.

Software 1430 may include code to implement aspects of the present disclosure， including code to support encoding and decoding for messages with partial common content. Software 1430 may be stored in a non-transitory computer-readable medium such as system memory or other memory. In some cases， the software 1430 may not be directly executable by the processor but may cause a computer (e.g.， when compiled and executed) to perform functions described herein.

Transceiver 1435 may communicate bi-directionally， via one or more antennas， wired， or wireless links as described above. For example， the transceiver 1435 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1435 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission， and to demodulate packets received from the antennas.

In some cases， the wireless device may include a single antenna 1440. However， in some cases the device may have more than one antenna 1440， which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

I/O controller 1445 may manage input and output signals for device 1405. I/O controller 1445 may also manage peripherals not integrated into device 1405. In some cases， I/O controller 1445 may represent a physical connection or port to an external peripheral. In some cases， I/O controller 1445 may utilize an operating system such as

or another known operating system. In other cases， I/O controller 1445 may represent or interact with a modem， a keyboard， a mouse， a touchscreen， or a similar device. In some cases， I/O controller 1445 may be implemented as part of a processor. In some cases， a user may interact with device 1405 via I/O controller 1445 or via hardware components controlled by I/O controller 1445.

FIG. 15 shows a flowchart illustrating a method 1500 for encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. The operations of method 1500 may be implemented by a base station 105 or its components as described herein. For example， the operations of method 1500 may be performed by a base station communications manager as described with reference to FIGs. 7 through 10. In some examples， a base station 105 may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively， the base station 105 may perform aspects of the functions described below using special-purpose hardware.

At 1505 the base station 105 may apply an encoding operation to a first input vector to generate a first component codeword to be used for a plurality of codewords transmitted in a plurality of corresponding time intervals. The operations of 1505 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1505 may be performed by a encoder as described with reference to FIGs. 7 through 10.

At 1510 the base station 105 may apply the encoding operation to a plurality of second input vectors to generate a respective plurality of second component codewords. The operations of 1510 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1510 may be performed by a encoder as described with reference to FIGs. 7 through 10.

At 1515 the base station 105 may combine， for each of the plurality of codewords， the first component codeword with a respective second component codeword. The operations of 1515 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1515 may be performed by a codeword combiner as described with reference to FIGs. 7 through 10.

At 1520 the base station 105 may transmit the plurality of codewords in the plurality of corresponding time intervals. The operations of 1520 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1520 may be performed by a transmission controller as described with reference to FIGs. 7 through 10.

FIG. 16 shows a flowchart illustrating a method 1600 for encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. The operations of method 1600 may be implemented by a UE 115 or its components as described herein. For example， the operations of method 1600 may be performed by a UE communications manager as described with reference to FIGs. 11 through 14.In some examples， a UE 115 may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively， the UE 115 may perform aspects of the functions described below using special-purpose hardware.

At 1605 the UE 115 may receive a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits. The operations of 1605 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1605 may be performed by a monitoring component as described with reference to FIGs. 11 through 14.

At 1610 the UE 115 may receive a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits. The operations of 1610 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1610 may be performed by a monitoring component as described with reference to FIGs. 11 through 14.

At 1615 the UE 115 may identify a difference between the first codeword and the second codeword. The operations of 1615 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1615 may be performed by a differential identifier as described with reference to FIGs. 11 through 14.

At 1620 the UE 115 may decode the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits. The operations of 1620 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1620 may be performed by a decoder as described with reference to FIGs. 11 through 14.

FIG. 17 shows a flowchart illustrating a method 1700 for encoding and decoding for messages with partial common content in accordance with aspects of the present disclosure. The operations of method 1700 may be implemented by a UE 115 or its components as described herein. For example， the operations of method 1700 may be performed by a UE communications manager as described with reference to FIGs. 11 through 14. In some examples， a UE 115 may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively， the UE 115 may perform aspects of the functions described below using special-purpose hardware.

At 1705 the UE 115 may receive a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits. The operations of 1705 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1705 may be performed by a monitoring component as described with reference to FIGs. 11 through 14.

At 1710 the UE 115 may receive a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits. The operations of 1710 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1710 may be performed by a monitoring component as described with reference to FIGs. 11 through 14.

At 1715 the UE 115 may apply a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword. The operations of 1715 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1715 may be performed by a differential applier as described with reference to FIGs. 11 through 14.

At 1720 the UE 115 may combine the second codeword and the hypothesized second codeword to obtain a combined codeword. The operations of 1720 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1720 may be performed by a combining component as described with reference to FIGs. 11 through 14.

At 1725 the UE 115 may perform a decoding operation on the combined codeword to obtain a representation of the second input vector. The operations of 1725 may be performed according to the methods described herein. In certain examples， aspects of the operations of 1725 may be performed by a decoder as described with reference to FIGs. 11 through 14.

It should be noted that the methods described above describe possible implementations， and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further， aspects from two or more of the methods may be combined.

Techniques described herein may be used for various wireless communications systems such as code division multiple access (CDMA) ， time division multiple access (TDMA) ， frequency division multiple access (FDMA) ， orthogonal frequency division multiple access (OFDMA) ， single carrier frequency division multiple access (SC-FDMA) ， and other systems. A CDMA system may implement a radio technology such as CDMA2000， Universal Terrestrial Radio Access (UTRA) ， etc. CDMA2000 covers IS-2000， IS-95， and IS-856 standards. IS-2000 Releases may be commonly referred to as CDMA2000 1X， 1X， etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO， High Rate Packet Data (HRPD) ， etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system may implement a radio technology such as Global System for Mobile Communications (GSM) .

An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB) ， Evolved UTRA (E-UTRA) ， Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) ， IEEE 802.16 (WiMAX) ， IEEE 802.20， Flash-OFDM， etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS) . LTE and LTE-Aare releases of UMTS that use E-UTRA. UTRA， E-UTRA， UMTS， LTE， LTE-A， NR， and GSM are described in documents from the organization named “3rd Generation Partnership Project” (3GPP) . CDMA2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . The techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies. While aspects of an LTE or an NR system may be described for purposes of example， and LTE or NR terminology may be used in much of the description， the techniques described herein are applicable beyond LTE or NR applications.

A macro cell generally covers a relatively large geographic area (e.g.， several kilometers in radius) and may allow unrestricted access by UEs 115 with service subscriptions with the network provider. A small cell may be associated with a lower-powered base station 105， as compared with a macro cell， and a small cell may operate in the same or different (e.g.， licensed， unlicensed， etc. ) frequency bands as macro cells. Small cells may include pico cells， femto cells， and micro cells according to various examples. A pico cell， for example， may cover a small geographic area and may allow unrestricted access by UEs 115 with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g.， a home) and may provide restricted access by UEs 115 having an association with the femto cell (e.g.， UEs 115 in a closed subscriber group (CSG) ， UEs 115 for users in the home， and the like) . An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB， a pico eNB， a femto eNB， or a home eNB. An eNB may support one or multiple (e.g.， two， three， four， and the like) cells， and may also support communications using one or multiple component carriers.

The wireless communications system 100 or systems described herein may support synchronous or asynchronous operation. For synchronous operation， the base stations 105 may have similar frame timing， and transmissions from different base stations 105 may be approximately aligned in time. For asynchronous operation， the base stations 105 may have different frame timing， and transmissions from different base stations 105 may not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations.

Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example， data， instructions， commands， information， signals， bits， symbols， and chips that may be referenced throughout the above description may be represented by voltages， currents， electromagnetic waves， magnetic fields or particles， optical fields or particles， or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor， a digital signal processor (DSP) ， an application-specific integrated circuit (ASIC) ， a field-programmable gate array (FPGA) or other programmable logic device (PLD) ， discrete gate or transistor logic， discrete hardware components， or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor， but in the alternative， the processor may be any conventional processor， controller， microcontroller， or state machine. A processor may also be implemented as a combination of computing devices (e.g.， a combination of a DSP and a microprocessor， multiple microprocessors， one or more microprocessors in conjunction with a DSP core， or any other such configuration) .

The functions described herein may be implemented in hardware， software executed by a processor， firmware， or any combination thereof. If implemented in software executed by a processor， the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example， due to the nature of software， functions described above can be implemented using software executed by a processor， hardware， firmware， hardwiring， or combinations of any of these. Features implementing functions may also be physically located at various positions， including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example， and not limitation， non-transitory computer-readable media may comprise random-access memory (RAM) ， read-only memory (ROM) ， electrically erasable programmable read only memory (EEPROM) ， flash memory， compact disk (CD) ROM or other optical disk storage， magnetic disk storage or other magnetic storage devices， or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer， or a general-purpose or special-purpose processor. Also， any connection is properly termed a computer-readable medium. For example， if the software is transmitted from a website， server， or other remote source using a coaxial cable， fiber optic cable， twisted pair， digital subscriber line (DSL) ， or wireless technologies such as infrared， radio， and microwave， then the coaxial cable， fiber optic cable， twisted pair， DSL， or wireless technologies such as infrared， radio， and microwave are included in the definition of medium. Disk and disc， as used herein， include CD， laser disc， optical disc， digital versatile disc (DVD) ， floppy disk and Blu-ray disc where disks usually reproduce data magnetically， while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

As used herein， including in the claims， “or” as used in a list of items (e.g.， a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that， for example， a list of at least one of A， B， or C means A or B or C or AB or AC or BC or ABC (i.e.， A and B and C) . Also， as used herein， the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example， an exemplary step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words， as used herein， the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. ”

In the appended figures， similar components or features may have the same reference label. Further， various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification， the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label， or other subsequent reference label.

The description set forth herein， in connection with the appended drawings， describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example， instance， or illustration， ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques， however， may be practiced without these specific details. In some instances， well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

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

Claims

A method for wireless communication， comprising：

applying an encoding operation to a first input vector to generate a first component codeword to be used for a plurality of codewords transmitted in a plurality of corresponding time intervals；

applying the encoding operation to a plurality of second input vectors to generate a respective plurality of second component codewords；

combining， for each of the plurality of codewords， the first component codeword with a respective second component codeword； and

transmitting the plurality of codewords in the plurality of corresponding time intervals.
The method of claim 1， wherein each second input vector comprises a respective coded sequence， a difference between any coded sequences that correspond to adjacent time intervals being distinct from any other difference between coded sequences corresponding to adjacent time intervals.
The method of any of claims 1 or 2， wherein the first input vector is associated with a first set of bit positions of the encoding operation having a first decoding error rate and each second input vector is associated with a second set of bit positions of the encoding operation having a second decoding error rate lower than the first decoding error rate.
The method of claim 3， wherein the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of highest reliability bit channels.
The method of claim 3， wherein the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar code.
The method of any of claims 1 through 5， wherein each of the plurality of second input vectors comprises a bit stream corresponding to a respective system frame number (SFN) .
The method of claim 6， wherein each of the plurality of second input vectors comprises a respective plurality of error detecting check bits covering the respective SFN and a payload of the first input vector.
The method of any of claims 1 through 7， wherein each of the plurality of codewords comprises a physical broadcast channel (PBCH) .
The method of any of claims 1 through 8， wherein the encoding operation comprises a linear encoding operation.
A method for wireless communication， comprising：

receiving a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits；

receiving a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits；

identifying a difference between the first codeword and the second codeword； and

decoding the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits.
The method of claim 10， wherein identifying the difference comprises：

performing a log-likelihood ratio (LLR) exclusive-or (XOR) operation between codeword values for each bit position of the first and second codewords.
The method of any of claims 10 or 11， wherein the set of fixed bits is associated with a first set of bit positions of a decoding operation having a first decoding error rate and a respective set of variable bits is associated with a second set of bit positions of the decoding operation having a second decoding error rate lower than the first decoding error rate.
The method of claim 12， wherein the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of highest reliability bit channels.
The method of claim 12， wherein the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar decoding operation.
The method of claim any of claims 10 through 14， wherein the first set of variable bits comprises a first variable payload and a first plurality of error detecting check bits covering the first variable payload and the set of fixed bits.
The method of claim 15， wherein the first variable payload comprises a system frame number (SFN) .
The method of any of claims 10 through 16， wherein each of the first and second codewords comprises a physical broadcast channel (PBCH) .
A method for wireless communication， comprising：

receiving a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits；

receiving a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits；

applying a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword；

combining the second codeword and the hypothesized second codeword to obtain a combined codeword； and

performing a decoding operation on the combined codeword to obtain a representation of the second input vector.
The method of claim 18， further comprising：

receiving a third codeword generated from a third input vector comprising a third set of variable bits and the set of fixed bits；

applying a difference between the third codeword and the second codeword to the third codeword to obtain a second hypothesized second codeword；

combining the second codeword， the hypothesized second codeword， and the second hypothesized second codeword to obtain a second combined codeword； and

performing the decoding operation on the second combined codeword to obtain a second representation of the second input vector.
The method of any of claims 18 or 19， wherein applying the difference between the first codeword and the second codeword comprises：

decoding a difference vector to generate a decoding candidate；

re-encoding the decoding candidate to produce a candidate variable component codeword； and

performing a log-likelihood ratio (LLR) exclusive-or (XOR) operation between codeword values for each bit position of the first codeword and the candidate variable component codeword.
An apparatus for wireless communication， comprising：

means for applying an encoding operation to a first input vector to generate a first component codeword to be used for a plurality of codewords transmitted in a plurality of corresponding time intervals；

means for applying the encoding operation to a plurality of second input vectors to generate a respective plurality of second component codewords；

means for combining， for each of the plurality of codewords， the first component codeword with a respective second component codeword； and

means for transmitting the plurality of codewords in the plurality of corresponding time intervals.
The apparatus of claim 21， wherein each second input vector comprises a respective coded sequence， a difference between any coded sequences that correspond to adjacent time intervals being distinct from any other difference between coded sequences corresponding to adjacent time intervals.
The apparatus of any of claims 21 or 22， wherein the first input vector is associated with a first set of bit positions of the encoding operation having a first decoding error rate and each second input vector is associated with a second set of bit positions of the encoding operation having a second decoding error rate lower than the first decoding error rate.
The apparatus of claim 23， wherein the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of highest reliability bit channels.
The apparatus of claim 23， wherein the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar code.
The apparatus of any of claims 21 through 25， wherein each of the plurality of second input vectors comprises a bit stream corresponding to a respective system frame number (SFN) .
The apparatus of claim 26， wherein each of the plurality of second input vectors comprises a respective plurality of error detecting check bits covering the respective SFN and a payload of the first input vector.
The apparatus of any of claims 21 through 27， wherein each of the plurality of codewords comprises a physical broadcast channel (PBCH) .
The apparatus of any of claims 21 through 28， wherein the encoding operation comprises a linear encoding operation.
An apparatus for wireless communication， comprising：

means for receiving a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits；

means for receiving a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits；

means for identifying a difference between the first codeword and the second codeword； and

means for decoding the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits.
The apparatus of claim 30， wherein the means for identifying the difference comprises：

means for performing a log-likelihood ratio (LLR) exclusive-or (XOR) operation between codeword values for each bit position of the first and second codewords.
The apparatus of any of claims 30 or 31， wherein the set of fixed bits is associated with a first set of bit positions of a decoding operation having a first decoding error rate and a respective set of variable bits is associated with a second set of bit positions of the decoding operation having a second decoding error rate lower than the first decoding error rate.
The apparatus of claim 32， wherein the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of highest reliability bit channels.
The apparatus of claim 32， wherein the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar decoding operation.
The apparatus of any of claims 30 through 34， wherein the first set of variable bits comprises a first variable payload and a first plurality of error detecting check bits covering the first variable payload and the set of fixed bits.
The apparatus of claim 35， wherein the first variable payload comprises a system frame number (SFN) .
The apparatus of any of claims 30 through 36， wherein each of the first and second codewords comprises a physical broadcast channel (PBCH) .
An apparatus for wireless communication， comprising：

means for receiving a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits；

means for receiving a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits；

means for applying a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword；

means for combining the second codeword and the hypothesized second codeword to obtain a combined codeword； and

means for performing a decoding operation on the combined codeword to obtain a representation of the second input vector.
The apparatus of claim 38， further comprising：

means for receiving a third codeword generated from a third input vector comprising a third set of variable bits and the set of fixed bits；

means for applying a difference between the third codeword and the second codeword to the third codeword to obtain a second hypothesized second codeword；

means for combining the second codeword， the hypothesized second codeword， and the second hypothesized second codeword to obtain a second combined codeword； and

means for performing the decoding operation on the second combined codeword to obtain a second representation of the second input vector.
The apparatus of any of claims 38 or 39， wherein the means for applying the difference between the first codeword and the second codeword comprises：

means for decoding a difference vector to generate a decoding candidate；

means for re-encoding the decoding candidate to produce a candidate variable component codeword； and

means for performing a log-likelihood ratio (LLR) exclusive-or (XOR) operation between codeword values for each bit position of the first codeword and the candidate variable component codeword.
An apparatus for wireless communication， comprising：

a processor；

memory in electronic communication with the processor； and

instructions stored in the memory and executable by the processor to cause the apparatus to：

apply an encoding operation to a first input vector to generate a first component codeword to be used for a plurality of codewords transmitted in a plurality of corresponding time intervals；

apply the encoding operation to a plurality of second input vectors to generate a respective plurality of second component codewords；

combine， for each of the plurality of codewords， the first component codeword with a respective second component codeword； and

transmit the plurality of codewords in the plurality of corresponding time intervals.
The apparatus of claim 41， wherein each second input vector comprises a respective coded sequence， a difference between any coded sequences that correspond to adjacent time intervals being distinct from any other difference between coded sequences corresponding to adjacent time intervals.
The apparatus of any of claims 41 or 42， wherein the first input vector is associated with a first set of bit positions of the encoding operation having a first decoding error rate and each second input vector is associated with a second set of bit positions of the encoding operation having a second decoding error rate lower than the first decoding error rate.
The apparatus of claim 43， wherein the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of highest reliability bit channels.
The apparatus of claim 43， wherein the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar code.
The apparatus of any of claims 41 through 45， wherein each of the plurality of second input vectors comprises a bit stream corresponding to a respective system frame number (SFN) .
The apparatus of claim 46， wherein each of the plurality of second input vectors comprises a respective plurality of error detecting check bits covering the respective SFN and a payload of the first input vector.
The apparatus of any of claims 41 through 47， wherein each of the plurality of codewords comprises a physical broadcast channel (PBCH) .
The apparatus of any of claims 41 through 48， wherein the encoding operation comprises a linear encoding operation.
An apparatus for wireless communication， comprising：

a processor；

memory in electronic communication with the processor； and

instructions stored in the memory and executable by the processor to cause the apparatus to：

receive a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits；

receive a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits；

identify a difference between the first codeword and the second codeword； and

decode the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits.
The apparatus of claim 50， wherein the instructions to identify the difference are executable by the processor to cause the apparatus to：

perform a log-likelihood ratio (LLR) exclusive-or (XOR) operation between codeword values for each bit position of the first and second codewords.
The apparatus of any of claims 50 or 51， wherein the set of fixed bits is associated with a first set of bit positions of a decoding operation having a first decoding error rate and a respective set of variable bits is associated with a second set of bit positions of the decoding operation having a second decoding error rate lower than the first decoding error rate.
The apparatus of claim 52， wherein the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of highest reliability bit channels.
The apparatus of claim 52， wherein the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar decoding operation.
The apparatus of any of claims 50 through 54， wherein the first set of variable bits comprises a first variable payload and a first plurality of error detecting check bits covering the first variable payload and the set of fixed bits.
The apparatus of claim 55， wherein the first variable payload comprises a system frame number (SFN) .
The apparatus of any of claims 50 through 56， wherein each of the first and second codewords comprises a physical broadcast channel (PBCH) .
An apparatus for wireless communication， comprising：

a processor；

memory in electronic communication with the processor； and

instructions stored in the memory and executable by the processor to cause the apparatus to：

receive a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits；

receive a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits；

apply a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword；

combine the second codeword and the hypothesized second codeword to obtain a combined codeword； and

perform a decoding operation on the combined codeword to obtain a representation of the second input vector.
The apparatus of claim 58， wherein the instructions are further executable by the processor to cause the apparatus to：

receive a third codeword generated from a third input vector comprising a third set of variable bits and the set of fixed bits；

apply a difference between the third codeword and the second codeword to the third codeword to obtain a second hypothesized second codeword；

combine the second codeword， the hypothesized second codeword， and the second hypothesized second codeword to obtain a second combined codeword； and

perform the decoding operation on the second combined codeword to obtain a second representation of the second input vector.
The apparatus of any of claims 58 or 59， wherein the instructions to apply the difference between the first codeword and the second codeword are executable by the processor to cause the apparatus to：

decode a difference vector to generate a decoding candidate；

re-encode the decoding candidate to produce a candidate variable component codeword； and

perform a log-likelihood ratio (LLR) exclusive-or (XOR) operation between codeword values for each bit position of the first codeword and the candidate variable component codeword.
A non-transitory computer-readable medium storing code for wireless communication， the code comprising instructions executable by a processor to：

apply an encoding operation to a first input vector to generate a first component codeword to be used for a plurality of codewords transmitted in a plurality of corresponding time intervals；

apply the encoding operation to a plurality of second input vectors to generate a respective plurality of second component codewords；

combine， for each of the plurality of codewords， the first component codeword with a respective second component codeword； and

transmit the plurality of codewords in the plurality of corresponding time intervals.
The non-transitory computer-readable medium of claim 61， wherein each second input vector comprises a respective coded sequence， a difference between any coded sequences that correspond to adjacent time intervals being distinct from any other difference between coded sequences corresponding to adjacent time intervals.
The non-transitory computer-readable medium of any of claims 61 or 62， wherein the first input vector is associated with a first set of bit positions of the encoding operation having a first decoding error rate and each second input vector is associated with a second set of bit positions of the encoding operation having a second decoding error rate lower than the first decoding error rate.
The non-transitory computer-readable medium of claim 63， wherein the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of highest reliability bit channels.
The non-transitory computer-readable medium of claim 63， wherein the encoding operation applies a polar code， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar code.
The non-transitory computer-readable medium of any of claims 61 through 65， wherein each of the plurality of second input vectors comprises a bit stream corresponding to a respective system frame number (SFN) .
The non-transitory computer-readable medium of claim 66， wherein each of the plurality of second input vectors comprises a respective plurality of error detecting check bits covering the respective SFN and a payload of the first input vector.
The non-transitory computer-readable medium of any of claims 61 through 67， wherein each of the plurality of codewords comprises a physical broadcast channel (PBCH) .
The non-transitory computer-readable medium of any of claims 61 through 68， wherein the encoding operation comprises a linear encoding operation.
A non-transitory computer-readable medium storing code for wireless communication， the code comprising instructions executable by a processor to：

receive a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits；

receive a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits；

identify a difference between the first codeword and the second codeword； and

decode the difference between the first and second codewords to obtain at least one of the first set of variable bits or the second set of variable bits.
The non-transitory computer-readable medium of claim 70， wherein the instructions to identify the difference are executable by the processor to：

perform a log-likelihood ratio (LLR) exclusive-or (XOR) operation between codeword values for each bit position of the first and second codewords.
The non-transitory computer-readable medium of any of claims 70 or 71， wherein the set of fixed bits is associated with a first set of bit positions of a decoding operation having a first decoding error rate and a respective set of variable bits is associated with a second set of bit positions of the decoding operation having a second decoding error rate lower than the first decoding error rate.
The non-transitory computer-readable medium of claim 72， wherein the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of highest reliability bit channels.
The non-transitory computer-readable medium of claim 72， wherein the decoding operation is a polar decoding operation， and the second set of bit positions corresponds to a set of bit channels that occupy a set of terminal positions in a decoding order of the polar decoding operation.
The non-transitory computer-readable medium of any of claims 70 through 74， wherein the first set of variable bits comprises a first variable payload and a first plurality of error detecting check bits covering the first variable payload and the set of fixed bits.
The non-transitory computer-readable medium of claim 75， wherein the first variable payload comprises a system frame number (SFN) .
The non-transitory computer-readable medium of any of claims 70 through 76， wherein each of the first and second codewords comprises a physical broadcast channel (PBCH) .
A non-transitory computer-readable medium storing code for wireless communication， the code comprising instructions executable by a processor to：

receive a first codeword generated from a first input vector comprising a first set of variable bits and a set of fixed bits；

receive a second codeword generated from a second input vector comprising a second set of variable bits and the set of fixed bits；

apply a difference between the first codeword and the second codeword to the first codeword to obtain a hypothesized second codeword；

combine the second codeword and the hypothesized second codeword to obtain a combined codeword； and

perform a decoding operation on the combined codeword to obtain a representation of the second input vector.
The non-transitory computer-readable medium of claim 78， wherein the instructions are further executable by the processor to：

receive a third codeword generated from a third input vector comprising a third set of variable bits and the set of fixed bits；

apply a difference between the third codeword and the second codeword to the third codeword to obtain a second hypothesized second codeword；

combine the second codeword， the hypothesized second codeword， and the second hypothesized second codeword to obtain a second combined codeword； and

perform the decoding operation on the second combined codeword to obtain a second representation of the second input vector.
The non-transitory computer-readable medium of any of claims 78 or 79， wherein the instructions to apply the difference between the first codeword and the second codeword are executable by the processor to：

decode a difference vector to generate a decoding candidate；

re-encode the decoding candidate to produce a candidate variable component codeword； and

perform a log-likelihood ratio (LLR) exclusive-or (XOR) operation between codeword values for each bit position of the first codeword and the candidate variable component codeword.