Research On Key Technologies Of UWB High Performance Network Protocol

UWB network technology has become hot in the field of wireless communications research and development, and is considered one of the key technologies of next-generation wireless communications. No matter what the physical layer technology for UWB networks, there is no unified solution at the link layer technology yet. Although the industry standard ECMA-368 proposes a MAC sub-layer protocol, it doesn't involve the LLC sub-layer at all. In connection with unique characteristics of UWB network, an optimized communication link protocol covering MAC and the LLC sub-layer need to be designed. The protocol need not only ensure high reliability of data transmission, but also settle the problem of economy on energy, while also improve network throughput and network delay with less overhead for multi-hop UWB network scenarios to support all kinds of traffic with high quality of service. Supported by the National High Technology Research and Development Program of China under Grant No.2003AA12331005 and No.2009AA011202, our work is research and development of some key technologies for high-performance UWB network protocol with independent intellectual property rights.Based on the analysis of the current network protocols of multi-hop and UWB networks, the paper first proposes the problem to be solved and challenges in UWB multi-hop network protocol, and then brings forward the important problems we will solve. Accordingly, the overall research objectives is to design the LLC sub-layer protocol compatible with ECMA-368 MAC and PHY protocol and achieve high reliability of data transmission, economy on energy of nodes, high channel utilization ratio and high QoS guarantee of traffic. Under the guidance of the overall research goals, a UWB multi-hop network protocol model has been built, including the improvement of the MAC sub-layer protocol model and innovation of the LLC sub-layer protocol model, in which the technologies of IP header compression, TCP-acknowledge agent based on ARQ and Partial Window Multiple Rejects ARQ have been validated in major projects of B3G. While in the specific UWB environment, in particular multi-hop environment, the above technologies need further improvement. The next article will describe the specific measures for improvement of these technologies.Firstly, in the UWB multi-hop network applications, in order to save cost and power consumption, multi-hop needs to be used between nodes to relay data information. In multi-hop conditions, in order to ensure the quality of multimedia services and packet services, ARQ mechanism should be used to achieve reliable transmission of the data. There are many different characteristics between ARQ design in multi-hop and point to point application environments. Therefore, multi-hop ARQ mechanism should be designed to achieve high throughput, high efficiency of acknowledgement, low rates of retransmission and low delay, so that multimedia services requirements can be met. The design of UWB multi-hop network ARQ model this paper proposes combines the technology of innovative Partial Window Multiple Rejects ARQ and relay ARQ. It can not only meet the above design goals, but also accomplish the objectives of good compatibility with MAC and PHY protocol in ECMA-368 standard.Secondly, in the UWB multi-hop network, each device node has two functions of router and host, and most of the nodes adopt battery power supply. Therefore, with regard to device node, power saving is a very important problem. Since ARQ mechanism has been used in LLC sub-layer of UWB multi-hop network to ensure the quality of services of TCP business, while ARQ acknowledgement of LLC sub-layer and TCP acknowledgement of transmission layer has redundancy, we can receive TCP acknowledgement packet at the transmission node or the gateway generated by the transmission node or gateway AP of UWB network, according to ARQ information of LLC sub-layer and status track information of TCP connection. In this way, the receiver node can filter most of the TCP acknowledgement packet, reduce redundant information transfer among the nodes, and reduce the radiation power so as to achieve the purpose of energy saving of device node, and also solve the low throughput of wireless link caused by TCP congestion control mechanism.Thirdly, the service convergence sub-layer of UWB multi-hop network needs to support both IPv4 and IPv6 convergence, and TCP header, UDP header and IP header occupies a lot of wireless bandwidth resources, so efficient IP packet header compression algorithm based on IPv4 and IPv6 need to be studied. It should make use of the existing ARQ mechanism of LLC sub-layer to bring the consistency of header compression status information table of both communication sides. In this way, under the guarantee of consistent status table, more fields of TCP header, UDP header and IP header can be compressed to achieve higher compression ratio than that of current header compression algorithms.In summary, this article starts from improving the performance of UWB networks protocol, gives full consideration to the existing ECMA-368 standard features, and presents a new UWB network link layer protocol model suitable for multi-hop environment. Under this model, the paper analyzes the multi-hop ARQ mechanism, the TCP-acknowledge agent based on ARQ and IP header compression mechanism under the multi-hop environment in detail, then creates the network model, and uses the corresponding technical solutions in practical UWB multi-hop network. A large number of simulation experiments show that these solutions are effective to improve the network performance.