MU-MIMO Pre-Packet Arrival Channel Contention for Latency Reduction
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Solution Overview
Problem
Current wireless communication technologies, such as those using CSMA/CA, face challenges in achieving low latency required for real-time applications due to channel contention, power saving modes, and queuing delays, which are not adequately addressed by existing protocols like 802.11, leading to unreliable packet transmission in high-density environments.
Innovation Solution
The proposed solution involves modifying the MAC and PHY layers of 802.11 protocols to implement MU-MIMO transmission with pre-packet arrival contention, allowing Access Points to schedule resources before packet arrival and grant channel access early, reducing channel contention and latency for real-time applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CSMA/CA channel access protocol is used, then network throughput is improved, but packet latency increases
Solution Approach 1:
The patent applies preliminary action by allowing the AP to perform channel contention and secure channel access before the RTA packet actually arrives at the MAC layer. The AP contends for the channel in advance based on expected packet arrival timing, reserves the channel resource, and then transmits the packet immediately upon arrival without requiring the STA to perform separate channel access procedures. This eliminates the latency caused by CSMA/CA backoff and contention while maintaining network throughput through efficient resource utilization.
2Productivity
If random channel access is implemented, then channel utilization is improved, but worst-case latency is worsened
Solution Approach 1:
The patent implements preliminary action by having the AP proactively contend for channel access before the RTA packet arrives, rather than waiting for random access opportunities. The AP calculates the expected arrival time of RTA packets, initiates channel contention in advance, and secures the channel resource beforehand. This deterministic approach eliminates the randomness and unpredictable backoff delays inherent in traditional random access methods, ensuring bounded worst-case latency while maintaining high channel utilization through efficient pre-reservation.
3Reliability
If channel contention is required before each transmission, then collision avoidance is improved, but transmission delay increases
Solution Approach 1:
The patent applies preliminary action by performing channel contention in advance before the RTA packet arrives. The AP contends for the channel, secures access, and reserves the resource beforehand based on expected packet arrival timing. When the packet actually arrives, transmission can begin immediately without requiring another round of channel contention. This maintains collision avoidance through the initial contention while eliminating repeated transmission delays that would occur with traditional per-packet contention requirements.
4Use of energy by moving object
If power saving modes are used, then energy consumption is reduced, but packet delivery delay increases
Solution Approach 1:
The patent implements preliminary action by having the AP perform channel contention and prepare for transmission before the RTA packet arrives at the MAC layer. The AP secures channel access in advance, reserves resources, and maintains transmission readiness during the packet's transit time. When the packet arrives, the AP can immediately transmit without requiring the STA to wake from power-saving mode and perform channel access procedures, thereby reducing both energy consumption and packet delivery delay.
Data Source
AI summary
Systems, apparatus and methods for wireless local area network (WLAN) communication which support real-time application (RTA) packets. The access point (AP) schedules multiple-user (MU) multiple-input-multiple-output (MIMO) transmissions for uplink (UL) or downlink (DL) for RTA packets by allocating resources to packet transmissions before RTA packet arrival. The AP contends for channel access before the expected time of arrival of the RTA packet in the DL or UL direction. The operations reduce RTA packet latency on the WLAN.