Designing Heterogeneous MAC Protocols for Single-Channel Ad Hoc Wireless Networks

我的研究主要集中在寻找竞争为基础的MAC协议在单信道，单无线电ad hoc无线网络。特别是，考虑到我们研究的传统加拿大政府（GofC）网络，我们研究了允许网络节点使用不同规则访问网络的协议。 我们知道，大多数协议都给它们的基本服务集（BSS）节点相同的规则。这是为了确保公平性--要求所有节点对网络具有相同的访问权限。例如，在p-持久CSMA协议下，所有节点在退避过程中使用相同的概率p。我们把这种协议称为同质协议。 那么，协议具有“不同的规则”意味着什么呢？毕竟，协议就是规则。这就是我们的意思。假设我们考虑一个协议，其中我们将BSS划分为类，然后给每个类一个不同的规则。我们的工作表明，这样的协议可以设计为公平的（BSS中的每个节点具有相同的预期访问），如果BSS足够小，它还可以提高信道利用率（Hurley和Brimberg（2011））。我们把这种协议称为异构协议，我们认为它们是一类新的通用MAC协议。 重要的是要指出，“异构协议”和“混合协议”不是等价的术语。通常，协议被分类为基于竞争的（例如，CSMA/CA）或无竞争的（例如，TDMA），并且混合协议是采用某种混合的协议（例如，使用RTS/CTS握手的802.11 [DCF]）。但在混合协议中，通常所有节点都使用相同的规则，因此它们是同构协议。在这项研究中，我们正在研究采用异构规则的混合协议。

My research has focused on finding contention-based MAC protocols in single-channel, single radio ad hoc wireless networks. In particular, given the legacy Government of Canada (GofC) networks we study, we have looked at protocols which allow network nodes to use different rules to access the network. That we are aware, most protocols give their base service set (BSS) nodes the same rule. This is to ensure fairness—the requirement that all nodes have the same access to the network. For example, under the p-Persistent CSMA protocol, all nodes use the same probability p in the back-off procedure. We term such protocols homogenous protocols. So what does it mean for a protocol to have “different rules”? After all, a protocol is a rule. Here is what we mean. Suppose we consider a protocol where we partition the BSS into classes and then give each class a different rule. Our work has shown that such a protocol can be designed to be fair (each node in the BSS has the same expected access) and if the BSS is sufficiently small, it can also increase channel utilization (Hurley and Brimberg (2011)). We term such protocols heterogeneous protocols and we believe that they are a new general class of MAC protocol. It is important to point out that “heterogeneous protocols” and “hybrid protocols” are not equivalent terms. Generally, protocols have been classified as either contention-based (e.g. CSMA/CA) or contention-free (e.g. TDMA) and a hybrid protocol is one that employs some mixture (e.g. 802.11 [DCF] which uses a RTS/CTS handshake). But within a hybrid protocol, generally all nodes use the same rule and for that reason they are homogenous protocols. In this research, we are examining hybrid protocols that employ heterogeneous rules.