EDMG PPDU Transmission Using Golay Spreading and Cyclic Shifts
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Solution Overview
Problem
Current wireless communication systems in the millimeter-wave band face challenges in efficiently transmitting high-speed data, particularly in achieving multi-gigabit data rates over directional links, and supporting multiple user MIMO communications, which are essential for next-generation wireless networks like 5G and beyond.
Innovation Solution
The implementation of an Enhanced Directional Multi-Gigabit (EDMG) Physical Layer Protocol Data Unit (PPDU) format that includes specific fields and training sequences, along with a transmitter architecture that uses Golay sequences, LDPC encoding, and cyclic shift diversity to enable efficient transmission over multiple channels, supporting channel bonding and multi-user MIMO operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional wireless transmission methods are used in millimeter-wave band, then system simplicity is maintained, but data transmission rates cannot achieve multi-gigabit speeds
Solution Approach 1:
The PPDU is divided into multiple segments including legacy portion, EDMG portion, and TRN field with distinct functional components. The transmitter architecture is segmented into multiple transmit chains (first transmit chain, second transmit chain, etc.) that can be independently configured and operated, allowing complex multi-gigabit transmission functionality to be modularized and managed through separate processing units.
Solution Approach 2:
The patent introduces spatial dimensionality through multi-user MIMO by transmitting multiple spatial streams simultaneously across different transmit chains. Channel bonding extends the frequency dimension by aggregating multiple 2.16 GHz channels to achieve wider bandwidths (4.32 GHz, 6.48 GHz, 8.64 GHz). This multi-dimensional approach enables multi-gigabit data rates that cannot be achieved through single-dimensional improvements alone.
2Productivity
If channel bonding is implemented to increase bandwidth, then data rates improve, but signal synchronization and orthogonality become more difficult to maintain
Solution Approach 1:
Training sequences are inserted at multiple predetermined locations within the PPDU structure (in legacy portion, EDMG portion, and TRN field) before actual data transmission. These training sequences enable the receiver to perform channel estimation, synchronization, and equalization in advance, establishing accurate signal parameters before the high-rate bonded channel transmission begins, thereby maintaining synchronization accuracy across multiple bonded channels.
Solution Approach 2:
The patent employs cyclic shift diversity where the same training sequence is transmitted with different cyclic shifts across different transmit chains and spatial streams. This parameter transformation maintains orthogonality between multiple users and spatial streams while utilizing the bonded channel bandwidth, allowing the system to achieve high data rates without sacrificing synchronization precision through mathematical orthogonality preservation.
3Adaptability or versatility
If multi-user MIMO is supported to increase network capacity, then system versatility improves, but interference management and signal separation become more complex
Solution Approach 1:
The patent assigns different TRN field configurations to different spatial streams and users, with each transmit chain having its own training sequence and cyclic shift parameters. This segmentation allows the receiver to separately process and identify signals from different users and spatial streams, simplifying the interference management task by providing distinct identification markers for each spatial stream rather than requiring complex blind separation of overlapping signals.
Solution Approach 2:
Training sequences act as intermediary reference signals that facilitate the separation of multi-user MIMO signals. By inserting known training sequences with different cyclic shifts for different spatial streams, the receiver can use these intermediaries to estimate channel responses for each user independently, enabling effective interference cancellation and signal separation without requiring overly complex real-time processing of mixed signals.
4Reliability
If training sequences are inserted to improve channel estimation, then transmission reliability improves, but overhead increases reducing effective data rate
Solution Approach 1:
The training sequences in the patent serve multiple functions simultaneously: they enable channel estimation, provide synchronization references, support spatial stream identification through cyclic shifts, and facilitate receiver equalization. This multi-functionality reduces the need for separate reference signals for each function, thereby minimizing overhead while maintaining high transmission reliability through comprehensive channel characterization using a single set of training sequences.
Data Source
AI summary
An apparatus of a transmitter may include, for example, a Golay builder to build modulated Golay sequences for at least a non-EDMG Short Training Field (L-STF), and a non-EDMG Channel Estimation Field (L-CEF) of a PPDU; a scrambler to generate scrambled bits by scrambling bits of a non-EDMG header (L-header) and a data field of the PPDU; an encoder to encode the scrambled bits into encoded bits according to a low-density parity-check (LDPC) code; a constellation mapper to map the encoded bits into a stream of constellation points according to a constellation scheme; a spreader to spread the stream of constellation points according to a Golay sequence; and a transmit chain mapper to map a bit stream output from the Golay builder and the spreader to a plurality of transmit chains by applying a spatial expansion with relative cyclic shift over the plurality of transmit chains.