Electrical computers and digital processing systems: multicomput – Computer-to-computer data addressing
Reexamination Certificate
1999-09-28
2001-05-01
Maung, Zarni (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data addressing
C709S218000
Reexamination Certificate
active
06226686
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to computer network systems, and particularly to server group messaging systems and methods for reducing message rate and latency.
BACKGROUND OF THE INVENTION
There are a wide range of interactive applications implemented on computer systems today. All are characterized by dynamic response to the user. The user provides input to the computer and the application responds quickly. One popular example of interactive applications on personal computers (PCs) are games. In this case, rapid response to the user may mean redrawing the screen with a new picture in between 30 ms and 100 ms. Interactive applications such as games control the speed of their interaction with the user through an internal time base. The application uses this time base to derive rates at which the user input is sampled, the screen is redrawn and sound is played.
As computers have become more powerful and common, it has become important to connect them together in networks. A network is comprised of nodes and links. The nodes are connected in such a way that there exists a path from each node over the links and through the other nodes to each of the other nodes in the network. Each node may be connected to the network with one or more links. Nodes are further categorized into hosts, gateways and routers. Hosts are computer systems that are connected to the network by one link They communicate with the other nodes on the network by sending messages and receiving messages. Gateways are computer systems connected to the network by more than one link They not only communicate with the other nodes as do hosts, but they also forward messages on one of their network links to other nodes on their other network links. This processing of forwarding messages is called routing. In addition to sending and receiving messages and their routing functions, gateways may perform other functions in a network. Routers are nodes that are connected to the network by more than one link and whose sole function is the forwarding of messages on one network link to the other network links to which it is connected. A network consisting of many network links can be thought of as a network of sub-networks with gateways and/or routers connecting the sub-networks together into what is called an internet. Today the widely known example of a world wide internet is the so called “Internet” which in 1995 has over 10 million computers connected full time world-wide.
With so many computers on a single world-wide network, it is desirable to create interactive networked applications that bring together many people in a shared, networked, interactive application. Unfortunately, creating such shared, networked, interactive applications runs into the limitations of the existing network technology.
As an example, consider a game designed to be deployed over a network which is to be played by multiple players simultaneously. The game could be implemented in software on a PC connected to a network. A rate set by its internal time base, it would sample the inputs of the local user, receive messages from the network from the PCs of the other players and send messages out to the PCs of the other players. A typical rate will be ten times per second for a time period of 100 ms. The messages sent between the PCs would contain information that was needed to keep the game consistent between all of the PCs. In a game that created the illusion of a spatial environment where each player could move, the packets could contain information about the new positions of the players as they moved. Today there are many commercial examples of PC games that can be played between multiple players on Local Area Networks (LANs) or by two players over dial-up phone lines using modems. The network messages sent by such games contain a wide variety of information specific to the game. This can include position and velocity information of the objects in the game along with special actions taken by a player that effect the other players in the game.
The case of a two player game played over a modem is particularly simple. If the message rate is 10 messages per second, each PC sends 10 messages per second to the other PC and receives 10 messages per second. The delay introduced by the modems and phone line is small and will not be noticed in most games. Unfortunately, the case of two players is uninteresting for networked interactive applications. With the same game played with 8 players on a LAN, the message rate increases. Each PC must send 7 messages, one to each of the other 7 players every time period and will receive 7 messages from the other players in the same time period. If the messaging time period is 100 ms, the total message rate will be 70 messages sent per second and 70 messages received per second. As can be seen the message rate increases linearly with the number of players in the game. The message rates and data rates supported by popular LANs are high enough to support a large number of players at reasonable message sizes. Unfortunately, LANs are only deployed in commercial applications and cannot be considered for deploying a networked interactive application to consumer users.
The wide area networks available today to consumer users all must be accessed through dial-up phone lines using modems. While modem speeds have increased rapidly, they have now reached a bit rate of 28.8 Kbit/sec which is close to the limit set by the signal-to-noise ratio of conventional phone lines. Further speed increases are possible with ISDN, but this technology is not ready for mass market use. Other new wide area networking technologies are being discussed that would provide much higher bandwidth, but none are close to commercial operation. Therefore, in deploying a networked, interactive application to consumers, it is necessary to do so in a way that operates with existing networking and communications infrastructures.
In the example of the 8 player networked game, consider a wide area network implementation where the PCs of each of the players is connected to the network with a 28.8 Kbit/sec modem. Assume that the network used in this example is the Internet so that all of the network protocols and routing behavior is well defined and understood. If the game uses TCP/IP to send its messages between the PCs in the game, the Point-to-Point Protocol/(PPP) protocol over the dial-up phone lines can be advantageously used to compress the TCP/IP headers. Even so, a typical message will be approximately 25 bytes in size. Sent through the modem, this is 250 bits. The messages are sent 10 times per second to each of the other PCs in the game and received 10 times per second from the other PCs. This is 35.0 Kbits/sec which exceeds the capabilities of the modem by 20%. If the messages are reduced to 20 bytes, just 8 players can be supported, but this approach clearly cannot support networked interactive applications with large numbers of participants. There are other problems beyond just the bandwidth of the network connection. There is the loading on each PC caused by the high packet rates and there is the latency introduced by the time needed to send all of the outbound packets. Each packet sent or received by a PC will require some amount of processing time. As the packet rate increases with the number of players in the game, less and less of the processor will be available for running the game software itself. Latency is important in an interactive application because it defines the responsiveness of the system. When a player provides a new input on their system, it is desirable for that input to immediately affect the game on all of the other players systems. This is particularly important in any game where the game outcome depends on players shooting at targets that are moved by the actions of the other players. Latency in this case will be the time from when a player acts to move a target to the time that the target has moved on the screens of the other players in the game. A major portion of this latency will come from the time needed
Kwiatkowski Marc Peter
Rothschild Jeffrey Jackiel
Samuel Daniel Joseph
HearMe
Maung Zarni
Sterne Kessler Goldstein & Fox PLLC
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