Wireless LAN Channel Access Slot Allocation
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Solution Overview
Problem
In WLAN systems, terminals in power saving mode experience channel access competition and collisions when transmitting PS-poll frames, leading to unnecessary power consumption and retransmissions due to hidden node problems and channel access collisions.
Innovation Solution
A channel access method where terminals and access points use scheduling information from beacon frames to determine allocated channel access slots, allowing for coordinated data transmission requests and allocations, reducing collisions and power consumption by optimizing channel access timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If terminals transmit PS-poll frames simultaneously to request data from AP, then data transmission efficiency is improved, but channel access competition occurs causing collisions among PS-poll frames
Solution Approach 1:
The patent applies preliminary action by having the AP pre-allocate specific channel access slots to terminals before data transmission. The AP includes slot allocation information in beacon frames, allowing terminals to know in advance when they can transmit PS-poll frames without competition. This resolves the contradiction by eliminating simultaneous transmissions that cause collisions while maintaining efficient data transmission.
Solution Approach 2:
The patent segments the channel access time into distinct slots allocated to different terminals. Instead of allowing simultaneous access, the channel is divided into time segments where each terminal has a dedicated transmission window. This segmentation prevents collisions among PS-poll frames while maintaining overall system productivity through structured access.
2Reliability
If terminals maintain awake state or retransmit PS-poll frames due to collisions, then data reception reliability is improved, but power consumption increases significantly
Solution Approach 1:
The patent uses preliminary action by providing slot allocation information in advance through beacon frames. Terminals can enter power-saving mode during allocated slots rather than maintaining continuous awake state or performing repeated retransmissions. This resolves the contradiction by ensuring reliable data reception through pre-coordinated access while minimizing power consumption through efficient sleep-wake cycles.
Solution Approach 2:
The patent enables terminals to self-manage their power consumption by using the slot allocation information to autonomously determine when to wake up and transmit PS-poll frames. Each terminal independently follows the scheduled slots, eliminating the need for continuous monitoring or reactive retransmission attempts, thus achieving reliable communication with minimal energy expenditure.
3Reliability
If AP allocates channel access slots based on beacon information, then channel access competition is prevented, but system complexity increases due to scheduling management
Solution Approach 1:
The patent applies universality by using the existing beacon frame structure for dual purposes: traditional network synchronization and new slot allocation information distribution. The same beacon mechanism that already exists for timing synchronization is extended to carry slot allocation data, avoiding the need for separate complex scheduling protocols and minimizing additional system complexity.
Solution Approach 2:
The patent merges the slot allocation function with the existing beacon frame transmission. Instead of creating a separate scheduling system, the allocation information is combined with the regular beacon updates that terminals already process for synchronization. This integration approach prevents channel access competition while avoiding the overhead of independent scheduling infrastructure.
Data Source
AI summary
A channel access method in a wireless LAN system is disclosed. The channel access method for a terminal comprises the steps of: receiving a beacon transmitted from an access point; determining a channel access slot of a terminal allocated on the basis of the beacon; transmitting a data transmission request from the channel access slot to the access point; and receiving data transmission slot allocation information corresponding to the data transmission request from the access point. Thus, the present invention can reduce power consumption of the terminal.