那些解决方案是根据具体行业、业务领域和客户在其早期设计阶段的需求制定的，无法建立可追踪性。
Those solutions were made specific to individual industry, business domain and customer needs at their early design stage, no traceability could be established.
“你必须更好的根据具体情况制定解决方案，这就更昂贵和更困难了，”Lewis说。
"You've got to tailor things better, and that makes it more expensive and more difficult," says Lewis.
尽管在IEEE 802.16标准中已经定义了带宽预留的消息和方式等，但并未制定具体的实现方案等。
IEEE standard 802.16 has already defined the message and method of prearranged bandwidth, but do not give the concretely realized scheme.
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