Opinion ID: 2757602
Heading Depth: 2
Heading Rank: 2

Heading: Ericsson’s SEPs

Text: Ericsson has asserted that all of the patents at issue are SEPs for IEEE’s 802.11(n) standard. Ericsson promised to offer licenses for all of its 802.11(n) SEPs at a RAND rate via letters of assurance to the IEEE. In its letters, Ericsson pledged to “grant a license under reasonable rates to an unrestricted number of applicants on a worldwide basis with reasonable terms and conditions that are demonstrably free of unfair discrimination.” Joint Appendix (“J.A.”) 17253. The parties agree that this commitment is binding on Ericsson. See also IEEE Br. 19–20.
The ’568 patent, titled “Multi-Rate Radio- communication Systems and Terminals,” describes prioritizing packets based on the type of payload in the packet. The prioritization of packets is important because networks all have a bandwidth limitation. Bandwidth refers to the amount of data that can be sent across the network at one time. When a network receives multiple requests at the same time, it must be able to respond to all of the requests in a timely fashion. Due to the network’s bandwidth limitation, however, the messages cannot be sent all at once. Though networks can deal with the bandwidth limitation problem in different ways, each method ERICSSON, INC. v. D-LINK SYSTEMS, INC. 9 involves dividing the available bandwidth among the outstanding requests. The ’568 patent explains that networks transmit a variety of different types of payloads, including “voice, video, and data.” According to the ’568 patent, networks in the prior art did not have the ability to prioritize certain types of data over others. Because certain types of transmissions are less preferable when delayed—e.g., voice calling—the ’568 patent discloses transmitting the type of transmission as part of the header. This would allow the network to dedicate more bandwidth to the higher priority transmission types, thereby sending those packets more quickly. Claims 1 and 5 are at issue in this appeal. Claim 1 is representative: 1. A communications station comprising: a processor for arranging information for trans- mission including providing at least one first field in which payload information is disposed and providing at least one second field, separate from said first field, which includes a service type identifier which identifies a type of payload infor- mation provided in said at least one first field; and a transmitter for transmitting information re- ceived from said processor including said at least one first field and said at least one second field. ’568 patent col. 13 ll. 11–21 (emphasis added).
As described above, files are broken into packets, which are sent to the receiving device with sequence numbers so the receiving device can reassemble the payload in the correct order. Packets, however, are often lost or corrupted during transmission. To ensure that the receiver receives the payload in those lost or corrupted 10 ERICSSON, INC. v. D-LINK SYSTEMS, INC. packets, the transmitter will have to resend those packets. For the transmitter to know which packets need to be resent, the receiving device must tell the transmitting device which packets it did not receive or are corrupted. This may be done using an “Automatic Repeat Request” (“ARQ”) protocol. In an ARQ protocol, the receiving device will send a “feedback response” to the transmitting device. Though feedback response messages can be in different formats, the feedback response will generally indicate which packets, if any, are missing or corrupted. The transmitting device will then retransmit those missing packets. Although ARQ protocols existed in the prior art, the ’215 patent, titled “Method for Minimizing Feedback Responses in ARQ Protocols,” asserts that those prior art ARQ protocols wasted bandwidth because they were “static” and not adaptable. By making the feedback response type dynamic, the ’215 patent discloses that the response could be formatted in the most efficient response type. For example, if 1 packet out of 100 is missing, just the missing packet number could be sent. Conversely, if 50 out of 100 packets are missing, the response could be a bitmap with a bit set to one to indicate the missing packets, instead of a list of all 50 missing packet numbers. To solve this alleged deficiency in the prior art, the ’215 patent discloses adding a “type identifier field” (“TIF”) to the feedback response that identifies the format of that feedback response. This would allow the receiver to choose dynamically between different types of feedback responses based on which response would be most efficient, e.g., a list of packet numbers or a bitmap. Claim 1 is the independent claim at issue: 1. A method for minimizing feedback responses in an ARQ protocol, comprising the steps of: sending a plurality of first data units over a com- munication link; ERICSSON, INC. v. D-LINK SYSTEMS, INC. 11 receiving said plurality of first data units; and responsive to the receiving step, constructing a message field for a second data unit, said message field including a type identifier field and at least one of a sequence number field, a length field, and a content field. ’215 patent col. 10 ll. 19–28 (emphasis added).
Due to technical limitations, prior art receiving devices used a limited “reception window” for keeping track of which packets it had received. Because this reception window was finite, if the receiving device received a packet outside of the window, it would not accept the packet. The window would not move forward until it received all of the packets in the current window. This process ensures that the receiver will receive all of the missing packets. For certain “delay sensitive applications,” however, a 0% packet loss rate is not required and significantly delayed packets provide no benefit—e.g., “telephony, video conferencing, and delay sensitive control systems.” ’625 patent col. 3 ll. 51–53. According to the ’625 patent, prior art transmitting devices had no way to tell the receiving device to ignore unnecessary, missing packets and shift the receiving window forward. The ’625 patent discloses adding a way for the transmitting device to force the receiving device to accept packets that may be out of its reception window. This will also shift the reception window forward and the receiving device will forget about the delayed or lost packets that would no longer provide any benefit. Claim 1 is at issue in this appeal: 1. A method for discarding packets in a data net- work employing a packet transfer protocol includ12 ERICSSON, INC. v. D-LINK SYSTEMS, INC. ing an automatic repeat request scheme, compris- ing the steps of: a transmitter in the data network commanding a receiver in the data network to a) receive at least one packet having a sequence number that is not consecutive with a sequence number of a previous- ly received packet and b) release any expectation of receiving outstanding packets having sequence numbers prior to the at least one packet; and the transmitter discarding all packets for which acknowledgment has not been received, and which have sequence numbers prior to the at least one packet. ’625 patent col. 10 ll. 13–26 (emphases added).