HFC网络中MAC协议的研究

论述了在HFC中传输数据业务的内容，主要讨论了符合DOCSIS标准的MAC协议所应该考虑到的一些内容，包括上行传输机制，MAC协议的帧格式以及管理信息，最后介绍了CM和CMTS的交互作用。     

Adaptive digital access protocol: a MAC protocol for multiservicebroadband access networks

The authors describe a protocol that can adapt to the changing demands of a mix of synchronous transfer mode (STM) and asynchronous transfer mode (ATM) applications and efficiently allocate bandwidth to a variety of bursty traffic sources. In the case of a hybrid fiber-coaxial (HFC) network, the protocol resides in customer premises equipment (CPE) and a common head-end/central-office (HE/CO) controller. A medium-access control (MAC) processor provides for dividing the time domain for a given digital bitstream into successive frames, each with multiple STM and ATM time slots. Within the STM region of a frame, variable-length time slots are allocated to calls (e.g., telephony, video telephony) requiring different amounts of bandwidth. In the upstream channels, a contention access signaling time slot is also provided in the STM region for call control and setup requests. Within the ATM region, fixed-length time slots accommodate one individual ATM cell. These ATM time slots may be reserved for a user for either the duration of a call or a burst of successive ATM cells, or shared via a contention process. At least one contention time slot is available for signaling messages related to ATM call control and setup requests. The MAC-layer protocol, its relation to circuit- and ATM-amenable applications, and its performance with respect to throughput, latency, and bandwidth efficiency for several service scenarios are examined     

A priority scheme for the IEEE 802.14 MAC protocol for hybridfiber-coax networks

In order to support quality-of-service (QoS) for real-time data communications such as voice, video and interactive services, multiaccess networks must provide an effective priority mechanism. The context of this work is the IEEE 802.14 standard for hybrid fiber coaxial (HFC) networks which has a shared upstream channel for transmissions from stations to the headend. This work presents a multilevel priority collision resolution scheme, which separates and resolves collisions between stations in a priority order, thereby, achieving the capability for preemptive priorities. We present a set of simulation scenarios which show the robustness and efficiency of the scheme, such as its ability to isolate higher priority traffic from lower priorities and to provide quick access to high-priority requests. In March 1998, a framework for handling priorities in the collision resolution process, which adopts a semantics similar to the semantics of our scheme, was included in the 802.14 standard     

HFC网络的MAC协议多优先级机制的改进算法

HFC网络的MAC协议内容包括多优先级业务的操作，通过对目前IEEE802.14协议提供的优先业务的能力进行研究，发现它的抢先竞争时隙分配器的能力有不足之处，为此提出一种支持多优先级的竞争时隙动态分配算法，用于改进IEEE802.14协议的冲突化解算法。     

On IEEE 802.14 medium access control protocol

In this article we present a comprehensive survey on the architecture, protocol issues, and standard of the hybrid fiber coaxial (HFC) networks which are evolving from the existing residential CATV networks. We first describe the HFC architecture and discuss the problems in providing two-way communication. Then, we identify three important medium access control (MAC) issues in designing the IEEE 802.14 standard; namely, synchronization, upstream channel access modes, and collision resolution. Resolutions adopted by the IEEE 802.14 Committee are illustrated after giving a protocol overview. Key resolutions include compensating round trip correction (RTC), interleaving minislots of data and request concurrently, and resolving collisions by multiple collision resolution engines, using the n-ary tree plus p-persistence algorithm with a first transmission rule. A comparative summary of some draft proposals that lead to the standard is given. Finally, we pinpoint two headend algorithms, minislot allocation and request scheduling, which are left open in the standard. They do not affect interoperability but may have a critical impact on performance.     

A dynamic control scheme for the IEEE 802.14 draft MAC protocolover CATV/HFC networks

We first describe the draft multiple/random access protocol for IEEE 802.14 over the cable TV/hybrid fiber coaxial (CATV/HFC) networks. To best fit this draft protocol into the target network, we propose a dynamic control scheme to adequately adjust the parameters. Simulations of the draft protocol are then presented to depict the effectiveness of the proposed scheme and further highlight the directions for the design of MAC protocols over the CATV/HFC networks     

Architecture and performance of a MAC protocol for the HFC system

The IEEE 802.14 standard committee is currently working on a project to find a cost-effective means of providing access to integrated networks for people to enjoy multimedia programs and to work at home. An advanced system based on the cable TV system called hybrid fibre coax (HFC) is being studied. Since some properties of the HFC system preclude the possibility of directly using existing medium access control (MAC) protocols for its data link layer, a MAC scheme based on time division is discussed in this paper. This MAC scheme can be extended for wireless networks. © 1997 John Wiley & Sons, Ltd.     

HFC网络MAC协议的冲突化解算法分析与改进

对HFC网络MAC协议注过程中的几种竞争冲突的化解算法进行分析，并提出了一种自适应P坚持算法，实验表明该算法的性能比其他可实现算法更好。     

Fair MAC protocol for optical ring network of wavelength-shared access nodes

In this paper, a WDM optical ring consisting of access nodes with fixed transmitter-n fixed receivers (FT—FR ⁿ ) is considered. As access nodes share a wavelength channel there is trade-off between node throughput and fairness among them. In order to abbreviate the transmission unfairness and to increase the throughput, we propose p-persistent medium access control (MAC) protocol. Each node uses the carrier sense multiple access with collision avoidance (CSMA/CA) protocol to transmit packets, and decides whether to use a local empty slot with probability p when a transferred packet based on source-stripping is dropped and emptied. Numerical prediction for the proposed MAC protocol is introduced to compute the maximum node throughput under uniform traffic condition. For more detail results, we use network simulation with self-similar traffic and introduce various results. The proposed MAC protocol gives better node throughput than non-persistent protocol and shows an improved fairness factor than 1-persistent protocol. Through simulation, we also find the reasonable probability of p-persistent protocol for a given architecture.     

APON接人系统的一个介质访问控制协议

作为共享介质的接入网络,APON需要介质访问控制协议用于协调各终端对介质的存取.本文提出了一个符合ITU-T建议的MAC协议,采用了时延分优先级,对高优先级的实时业务按照的均匀间隔的原则分配带宽,低优先级业务的带宽按次序循环分配.上行帧长度根据处于连接的用户数动态变化,各终端的带宽申请时隙由系统动态分配.最后给出了由该协议确定的网络性能的计算机仿真结果.     

动态频谱接入MAC协议研究

机会频谱接入（OSA,opportunistic spectrum access）允许未授权用户在空间域和时域上共享授权频谱,但仅当授权用户没有占用这些频谱时认知用户才能接入。另外频谱环境的动态性使MAC协议设计面临着几个重要的问题,即认知用户需要确定何时以什么方式接入哪一个信道发送/接收数据而不影响主用户的通信。从OSA-MAC设计面临的技术挑战出发,对近年来国内外在该方向的研究成果做了总结和分析,并阐述了OSA-MAC设计亟待解决的问题和今后的研究方向。     

HFC宽带接入网网络管理体系

在介绍了宽带HFC接入网之后，借鉴TMN相应要领，提出在HFC宽带接入网网络管理中采用TMN的体系结构，网络管理接口采用SNMP或Q3，最后说明了与更高层网络管理的互通问题。     

UW‐MAC: An underwater sensor network MAC protocol

As over 70% of the earth's surface is covered by water, it is desirable to deploy underwater sensor networks (UWSNs) to support oceanic research. UWSNs use acoustic waves and are characterized by long and variable propagation delays, intermittent connectivity, limited bandwidth and low bit rates. Energy savings have always been the primary concern in wireless sensor network protocols; however, there are applications where the latency and throughput are prioritized over energy efficiency and are so significant that the application would not be able to satisfy its requirements without them. Although existing duty‐cycle MAC protocols are power efficient, they introduce significant end‐to‐end delivery latency, provide poor throughput and are not suitable for the challenging environment of a UWSN. In this paper, we utilize CDMA as the underlying multiple access technique, due to its resilience to multi‐path and Doppler's effects prevalent in underwater environments. We propose UW‐MAC, a CDMA‐based power‐controlled medium access protocol that uses both transmitter‐based and receiver‐based CDMA inside a formed cluster, and uses a TDMA schedule to make the cluster heads communicate with the base station. Our MAC algorithm targets the latency and throughput needs in addition to its ability to increase the overall network lifetime. We discuss the design of UW‐MAC, and provide a head‐to‐head comparison with other protocols through extensive simulations focusing on the performance in terms of latency, throughput, and energy consumption. Copyright © 2009 John Wiley & Sons, Ltd.     

A new network architecture with intelligent node (IN) to enhanceIEEE 802.14 HFC networks

In the hybrid fiber/coax (HFC) architecture, a number of 500-2000 subscribers in the CATV (community antenna TV) network may cause serious collisions during the request phase. In this paper, we propose a new network architecture which using an intelligent node (IN) to stand for a group of subscribers to request the demand resources. The intelligent node has the ability to reduce the collision probability as well as the collision resolving period. The simulation results shown that the throughput and average buffer delay obtained by the proposed architecture is better than that of the standard architecture     

Cross layer access point selection mechanisms for a distributed queuing MAC protocol

The Distributed Queuing with Collision Avoidance (DQCA) Medium Access Control (MAC) protocol has been presented in the literature as a high-performance protocol for WLANs. Previous work regarding DQCA is focused on the operation of a single cell, where no interaction with neighboring sites is considered. In this paper, we define specific handoff procedures (channel sensing, discovery and reassociation functions) that enable the roaming of users in a scenario consisting of several DQCA access points (APs) deployed in a specific area using non-overlapping channel frequencies. Furthermore, we introduce a number of AP selection mechanisms in order to provide efficient reassociation decision criteria in the context of DQCA. These mechanisms are based either on a single metric such as the Signal to Noise Ratio (SNR) or the traffic load, or on cross-layer design by combining the information from different layers. Finally, our proposed solutions are evaluated by means of computer simulations.     

一种改进的宽带卫星网络MAC协议

为了提高宽带卫星网络上行信道资源的利用率,同时保障多媒体业务的不同服务质量要求,需要采用合适的媒体接入控制协议。BTDAMA可以显著减少自相似业务的等待时延,并且提高了资源利用率。但它没有区分业务类型,不能保证高优先级业务的服务质量,也造成了一定程度上资源的浪费。在BTDAMA的基础上提出了一种基于业务优先级的带宽分配算法,针对不同的业务类型采用不同的分配方案,不仅保证了各类业务的服务质量,同时提高了资源利用率。     

以HFC为基础的宽带综合业务接入网

对宽带综合业务接入网-光纤同轴电缆混合网技术进行了综述,介绍了HFC网的结构、频谱分配策略,以及实现双向通信的技术关键。同时对双向HFC网存在的主要问题：上行通道噪声漏斗效应、各种噪声干扰控制策略、回波反射等进行了说明。     

一种无线ATM网络的MAC协议

主要研究了无线ATM网络对MAC的需求，并介绍了适用于无线ATM的一种新的MAC方案。该协议支持不同类型信息传输，比如恒定比特率（CBR），可变比特率（VBR），可用比特率（ABR），未指定比特率（UBR）。另外此协议还提供了对宽带ATM主干网的无缝连接。同时也支持与ATM相关的QoS级别。对于该协议关注的各种情况的主要原理进行了讨论。     

HFC接入网上行传输通道均衡性的分析

主要对HFC接入网上行传输通道各个环节的均衡性进行了分析，指出电缆分配网络上行传输系统是制约网络多功能开发的主要因素之一，并针对有线电视网络现状提出了HFC接入网的改造思路。     

Hopping control channel MAC protocol for opportunistic spectrum access networks

Opportunistic spectrum access （OSA） is considered as a promising approach to mitigate spectrum scarcity by allowing unlicensed users to exploit spectrum opportunities in licensed frequency bands. Derived from the existing channel-hopping multiple access （CHMA） protocol,we introduce a hopping control channel medium access control （MAC） protocol in the context of OSA networks. In our proposed protocol,all nodes in the network follow a common channel-hopping sequence; every frequency channel can be used as control channel and data channel. Considering primary users＇ occupancy of the channel,we use a primary user （PU） detection model to calculate the channel availability for unlicensed users＇ access. Then,a discrete Markov chain analytical model is applied to describe the channel states and deduce the system throughput. Through simulation,we present numerical results to demonstrate the throughput performance of our protocol and thus validate our work.