Combining ACK rate control and AQM to enhance TCP performance over 3G links

ABSTRACT

When TCP is carried over 3G links, overbuffering and buffer overflow at the RLC layer degrades its performance. In order to prevent these undesired interactions, we propose an algorithm that combines two strategies. If the congestion state of the downlink buffer is moderate, the protocol uses ACK rate control to adjust the sending rate of the source. If the buffer occupancy reaches certain threshold, a single packet is discarded to trigger TCP congestion control measures. By means of extensive simulation experiments, we disclose the influence of each parameter on TCP performance, finding several configurations that improve end-to-end goodput while reducing the delay. The proposal is compared to other approaches, showing a better and more stable behaviour. The operation of the algorithm is deterministic; it does not require changes in 3G specifications nor in end user's protocol stack, and preserves TCP end-to-end semantics

REFERENCES

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INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS
      C.2.1 Network Architecture and Design
          Subjects: Wireless communication

Additional Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS
      C.2.2 Network Protocols
          Subjects: Applications (SMTP, FTP, etc.)

General Terms:
Algorithms, Performance

Keywords:
TCP over 3G links, radio link control (RLC)